Innovation and Modernization in Irrigation and Drainage A GUIDE TO WHY, WHAT, AND HOW Christopher Ward, Charles Burt, Svetlana Valieva, Ahmed Shawky, David Casanova, and David Meerbach About the Water Global Practice Launched in 2014, the World Bank Group’s Water Global Practice brings together financing, knowledge, and implementation in one platform. By combining the Bank’s global knowledge with country investments, this model generates more firepower for transformational solutions to help countries grow sustainably. Please visit us at www.worldbank.org/water or follow us on X: @WorldBankWater About GWSP This publication received the support of the Global Water Security & Sanitation Partnership (GWSP). 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Please visit us at www.worldbank.org/gwsp or follow us on X: @TheGwsp Innovation and Modernization in Irrigation and Drainage A GUIDE TO WHY, WHAT, AND HOW Christopher Ward, Charles Burt, Svetlana Valieva, Ahmed Shawky, David Casanova, and David Meerbach © 2024 International Bank for Reconstruction and Development / The World Bank 1818 H Street NW Washington DC 20433 Telephone: 202-473-1000 Internet: www.worldbank.org This work is a product of the staff of The World Bank with external contributions. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. 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Because The World Bank j button. encourages dissemination of its knowledge, this work may be reproduced, in whole To install the buttons in Adobe Reader, or in part, for noncommercial purposes as long as full attribution to this work is ¢ Right-click anywhere on the toolbar and select them in given. the Show Page Navigation Tools options; or Please cite the work as follows: ¢ open the View drop down menu and select them from Ward, Christopher, Charles Burt, Svetlana Valieva, Ahmed Shawky, David Casanova, the Page Navigation options. and David Meerbach. 2024. Innovation and Modernization in Irrigation and Drainage: A Guide to Why, What, and How. World Bank, Washington, DC. Alternatively, try using these keyboard shortcuts: Any queries on rights and licenses, including subsidiary rights, should be addressed Windows: Press the alt key and t or u arrow to World Bank Publications, The World Bank Group, 1818 H Street NW, Washington, Mac: Press the command key and [ or ] square bracket DC 20433, USA; fax: 202-522- 2625; e-mail: pubrights@worldbank.org. CONTENTS Chapter Three: The ‘What’ of I&M in I&D 30 I. System Level Structures and Operation Approaches 31 Irrigation Water Control 31 Irrigation Water Delivery and Scheduling 33 Water Measurement 35 Acronyms 6 Surface and Piped Water Conveyance 35 Drainage 35 Acknowledgments 7 II. Investing in Off-farm I&M 36 Introduction 8 The Nature of Off-farm I&M 36 The I&M Perspective 37 The Functions of Irrigation and Drainage 9 Canal vs. Piped Irrigation Schemes 41 Key Messages on I&M 11 Comparing Irrigation Modernization Approaches 42 A Limited Remit 15 Applying Innovations across Different Schemes and Purpose and Audience 15 Delivery Schedules 43 Organization of this Guide 15 Modernizing Off-farm Drainage 45 III. Investing in On-farm I&M 46 Chapter One: Defining the Nature and Purpose of I&M in I&D 17 What Do Farmers Want and How Can I&M Help? 46 The Approach to On-Farm Irrigation I&M 47 The I&M Mindset 18 The Essentials of On-Farm I&M 48 Typical Objectives of I&M 19 Improving Productivity through Water and Soil Management 53 Chapter Two: The ‘Why’ of I&M in I&D 20 On-Farm Drainage 55 The Problems to be Solved 21 The Goals to be Attained through I&M 21 Chapter Four: The ‘How’ of I&M in I&D 57 The Drivers of I&M 22 I. I&M Planning at the System Level 59 The Opportunities and Challenges Facing I&D Today 25 Developing and Implementing Modernization Plans 61 The Irrigation System Manager’s Perspective 25 An Iterative Process 62 The Farmer’s Perspective 27 The Importance of Well-Designed Participatory The Policy Maker’s Perspective 27 Processes   62 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE 3 Knowledge, Innovation, and Capacity: I&M as a 3.8 On-Farm Irrigation Design and Standards, Knowledge, and Knowledge-Based Approach 65 Support Network 174 Translating Service Delivery Principles into Plans 67 3.9 On-Farm Water Reservoirs 176 Formulating Planning and Design Considerations 70 3.10 Modernized Surface Irrigation 186 II. I&M at the Farm Level 79 3.11 Land Grading, Leveling, and Planing 195 The Framework Factors for I&M at the Farm Level 79 3.12 Linear and Center Pivot Sprinklers 203 Essential Conditions for Farmers to Plan, Implement, 3.13 Travelers and Hose Reel Sprinklers 214 and Operate Innovations 82 Disseminating Knowledge on, and Expanding 3.14 Drip/Micro Irrigation 220 Engagement with, Farm-Level I&M 84 3.15 Fertigation 231 Accompanying Measures: Government’s Role in 3.16 Soil and Plant Water Status and Irrigation Scheduling 240 Supporting Farmer-Led I&M 85 3.17 Telemetry with Focus on On-farm Systems 250 III. Promoting I&M at the National Level 86 3.18 Tile Drainage 259 Developing a Framework that Encourages I&M 86 4.1 Controlling Upstream Canal Water Levels with Long-Crested Weirs 266 Conclusion 89 4.2 Canal Lining 269 Glossary of Terms 92 Attachments 279 Technical Fiches 96 1. A Brief Historical Snapshot of Off-Farm Irrigation 280 3.1 Off-Farm Pipeline Conveyance 97 2. Flexibility of Water Deliveries under Rotation, Arranged, and 3.2 Flow Measurement and Control to Outlets (in Demand Delivery Schedules 282 Canals)   116 3. Improved Tillage and Furrow Formation 284 3.3 Canal Gates 125 4. Selection Criteria for On-Farm Technologies— 3.4 Canal Regulating Reservoirs 134 A Questionnaire   285 3.5 Automation with Programmable Logic Controllers 5. Innovation in Client Communication and Engagement 287 (PLC)   141 6. Factoring Modernization into Investment Projects 288 3.6 Supervisory Control and Data Acquisition System 7. Embracing Irrigation Innovation as a Fuzzy-Logic Process   289 (SCADA)   151 8. Procurement Strategy for Consulting Services for Irrigation and 3.7 Staffing 167 Drainage Projects   291 4 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Country Case Studies 301 LIST OF BOXES 1. Successful Planning and Implementation of Modernization in California, USA 302 2.1 Evaluating Water Service Delivery: Seven Tests of Its 2. Adoption of Laser Land Leveling in Punjab, Pakistan 304 Performance Quality 26 3. Modernization with Little Infrastructure or Equipment in 3.1 The Myth of Full Demand-based Irrigation Water Madhya Pradesh, India 305 Delivery   34 4. An Example of Learning by Doing in Morocco 306 3.2 Off-farm Use of Pipelines for Water Conveyance and Distribution 41 5. National Water Initiative Provided a Consensual Framework for Irrigation Modernization in Australia 308 3.3 On-Farm Water Storage 47 6. Irrigation Modernization in Brazil 309 3.4 Modernization for Precision Agriculture: Sequencing Infrastructure and Institutional Change 54 7. The National Irrigation Modernization Program in Argentina 311 3.5 Using ICT for Precision Agriculture in Vietnam   55 8. The Public and Private Sectors Working Together in 4.1 The Application of Water Accounting in I&M Israel   312 Planning   69 9. Irrigation Modernization in Spain 313 4.2 I&M Linkage with Irrigation Water Pricing Through Financial and Non-Financial Mechanisms   74 10. Drainage Water Reuse for Irrigation in Egypt 315 4.3 Integrating I&M Objectives into a National I&D Strategy: 11. Irrigation Modernization in the Sierra Region of Peru 316 An Example from Central Asia   87 12. Setting the Bar on Modernization: Canal de Provence in France 317 13. Enabling Access to Finance for Irrigation in Kenya 319 Bibliography 321 Photography 325 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE 5 ACRONYMS AMP Asset Management Planning AWD Alternate Wetting and Drying DSS Decision Support System ET Evapotranspiration I&D Irrigation and Drainage I&M Innovation and Modernization ICT Information and Communications Technology IWRM Integrated Water Resources Management KPI Key Performance Indicator LLL Laser Land Levelling M&E Monitoring and Evaluation MOM Management, Operation, and Maintenance O&M Operations and Maintenance OFWM On-Farm Water Management PA Precision Agriculture PLC Programmable Logic Controller SCADA Supervisory Control and Data Acquisition SRI System of Rice Intensification WUA Water Users Association 6 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE ACKNOWLEDGMENTS This guide was authored by Christopher Ward, Charles Burt, Svetlana Valieva, Ahmed Shawky, David Casanova, and David Meerbach. The broader task-preparation team that contributed to this task at various stages included Pieter Waalewijn, François Onimus, and Joop Stoutjesdijk in conceptualizing the guide, and Amal Talbi in supervising its finalization. Charles Burt prepared the technical fiches. Henri Carron, José Simas, Luis Ruiz Casquero, Atef Nassar, Charles Burt, Rémi Trier, and Safaa Bahije drafted the country case studies. Editing sup- port was provided by Franklyn Vardon-Ayensu. Dudu Coelho designed and laid out the publication. The World Bank team would like to recognize the support and guidance received from Dr. Luciano Mateos (1961-2022), pioneer in irrigation innovation and modernization. INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE 7 INTRODUCTION 8 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The Functions of Irrigation and Drainage Both irrigation and drainage (I&D) are vital to the proper development of crops. Irrigation1 is the ap- plication of water to plant roots to supply moisture needed for optimal plant growth. It complements water that is available to crops through precipita- tion and the moisture stored in the soil. Irrigation schemes have been used since times immemorial to enhance the availability of water at the crop root zone. A primary feature of an irrigation water supply scheme is its various hydraulic levels (or layers). Each hydraulic stratum supplies water to one be- 1 Factors that necessitate irrigation include: (i) inadequate precipitation, (ii) uneven distribution of low—through the primary, secondary, tertiary levels. precipitation (both spatially and temporally); (iii) growing several crops during a year; (iv) growing Scheme operators manage the higher levels within high-value and high yielding varieties of crops that require more stable supply of water; and (v) need for increased food, fodder, and fiber production. a hydraulic system, while the delivery points to 2 In addition to helping improve the productivity of soils, drainage also (i) facilitates trafficability farmers represent the lowest hydraulic level. for critical field operations such as plowing, planting, harvesting; (ii) lengthens the crop-growing season; (iii) decreases soil erosion by increasing soil filtration; (iv) favors growth of useful soil The primary function of drainage2 in agriculture is microorganisms; (v) leaches excess salts from the soil; and (vi) assures higher soil temperature. to remove excess water3 and salt from the soil and 3 Surplus water may include waste from the irrigated farms, surface runoff from snow and rainfall, to maintain an adequate supply of oxygen in the seepage and leakage from project canals and distribution schemes, artesian water, and percola- root zone for optimal plant development.4 Creation tion from farm irrigation. Many of these are return flows from a first-time use of the water supply and maintenance of a soil zone with optimal in a basin and should not be double counted as being additional supplies. moisture-oxygen-salt balance that permits normal 4 The presence of oxygen in the soil (in the root zone) is as necessary as water for both seed germination and plant growth. The oxygen content is markedly affected by the moisture content plant growth is one of the main requirements of of a soil. Moreover, agricultural production is tyipcally seriously affected when a saline water successful irrigated agriculture, alongside mainte- table rises and remains in the root zone longer than about 48 hours, resulting in abnormally high nance of healthy soils. saline moisture conditions. INTRODUCTION 9 In-line with the hydraulic system, there are two levels to I&D activities: Major infrastructural projects (e.g., roads and dams) on-farm and off-farm. Adequate design and subsequent operation of an deal with static designs, with relevant procedures well off-farm irrigation system enables sufficient control of water flow together explained and studied in universities. In contrast, I&D with the flexibility5 (frequency, flow rate, and duration) and efficiency of schemes are dynamic, deal with an elusive substance water delivery at every level of the scheme upstream of the farm or field (water) that is difficult to control and measure, require outlet. In turn, the level of water service delivery to the outlets influences substantial interaction with farmers and operators to the ability of farmers to properly manage their on-farm irrigation systems in function properly, and are subject to constantly chang- terms of meeting crop water requirements. ing weather and climate conditions as well as variable crop demands. A typical I&D scheme consists of: This guide addresses the variety of infrastructural in- n an intake structure or pumping station6 built at the entry to the irriga- vestments that are likely to provide the highest value tion scheme and delivering water from the primary water source (lake, for improving the performance of an I&D scheme as part river, reservoir, etc.) into its primary, secondary, and tertiary branches; of the efforts to innovate and modernize. Boosting the n a conveyance and distribution network (of canals and/or pipes) to performance of I&D schemes requires attention to both carry the water from the source to the farm; on- and off-farm aspects. Enhancement of on-farm irri- n an on-farm irrigation system; and gation management is dependent upon a reliable and flexible water supply to fields. Off-farm systems require n a drainage system. strategic and coordinated development to ensure that There are multiple variations of I&D schemes, ranging from large-scale all parts work together as a unit (as opposed to focusing collective arrangements that draw water from surface resources to small- on individual structures or technologies). An irrigation scale or individual irrigation schemes that use groundwater, water from scheme also needs to be operated as an interconnect- springs, or surface runoff.7 ed and dynamic system. While there is no doubt that improving on-farm irrigation water management is important, the off-farm water con- 5 Without built-in flexibility, schemes will not have the ability to match water deliveries to crop needs. veyance and distribution systems often face extremely serious challenges, with significant impacts on the farm- 6 A pump is used when the irrigation water source lies below the level of the irrigated fields. ing operations and the surrounding environment. In looking to successfully manage both, a question arises 7 Surface water runoff can be used for irrigation of agricultural crops during rainfall events. This is commonly accomplished by channeling the runoff water into dike-surrounded plots on the basic ingredients to moving forward towards the where crops are grown. desired goal. 10 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Key Messages on I&M Why Innovation and Modernization (I&M) in The world’s irrigation projects are operating in an unsustainable Irrigation Is Essential to the Future of the Planet water extraction mode. To recover sustainability, less water must be consumed in a smarter manner—as a way to increase the Rapidly expanding the productivity of irrigated agriculture is crop yield and quality per unit of water consumed. This requires vital in a century already marked by a huge rise in demand improved I&D systems and their management. In this setting, for agricultural products, and by increasingly volatile rainfall the operators of the primary (or main) level of the irrigation patterns and temperature trends. Furthermore, throughout the water supply scheme only have one responsibility—to fulfill their world, an overdraft of existing water resources is evidenced service obligation to their customers, who, in turn, operate the by the lack of environmental flows for rivers and depleting secondary level of the system.8 groundwater aquifers. The concept of service delivery is not restricted to the scheme and farmer interface. Rather, it extends to the operation of every hydraulic level in the scheme with a clear understanding by operators of their obligations at the interface between every layer and delivery points. Outdated I&D schemes (both off-farm and on-farm) currently constrain the output of much of the world’s irrigated land area. These old schemes yield poor, sometimes negligible irrigation outcomes and lackluster levels of agricultural production. They keep farmers in poverty, ruin ecosystems, and leave the global supply of food and natural fiber at the mercy of increasingly unpredictable rains. 8 However, in certain contexts, large government-run I&D schemes may not be operated as bottom-up organizations with a focus on farmers’ needs, while the concept of providing service may be entirely foreign to their staff (at all levels). INTRODUCTION 11 I&M in I&D, in the form of reliable new technologies, offers systemic change. In both patterns of change, the same forward-looking solutions to overcome these challenges. These higher-level outcomes—improved accuracy, reliability, flex- solutions aim to guide water and food systems into environmen- ibility, and equity of irrigation service delivery to farmers—are tally sustainable pathways toward better nutrition, ecological the goal. By focusing somewhat more on the second, this health, and earnings. I&M at the off-farm level is commonly guide shows how affordable, context appropriate I&M, under- undertaken to improve the accuracy, reliability, flexibility, and taken with a mindset open to learning, can help engender equity of I&D service delivery to end users—farmers. changes vital to our global future. Reliability addresses discrepancies between what was promised A Systems Approach to Goal Setting, Learning, (by the service provider) or what was assumed (by the customer) and Change in I&D versus what happens in reality. Equity deals with ensuring that I&M in I&D is not in itself the objective. It is a way to respond all customers have equal access to the services provided (and to a growing crisis in irrigated agriculture by engaging a are treated fairly). Flexibility focuses on the frequency, flow rate, continual process of adapting as various challenges and new and duration of irrigation events. While many irrigation project circumstances arise. I&M must be judged not by how modern planners have a vision of prioritizing very flexible water delivery or novel it is, but by how well it solves problems and meets service to fields, they commonly ignore the importance of need- existing needs. It is, first and foremost, a way of thinking, a ing a foundation of providing equity and reliability. mindset, a problem-solving approach founded on testing, Enhancing the responsiveness and precision of irrigation monitoring, learning from failures and successes, and scaling service delivery is particularly important because of the rising up what works. urgency of the need to move toward more flexible and reliable The I&M mindset includes a deliberate process of social, delivery schedules to customers (farmers), and away from the political, and engineering learning within a “sandbox” 9 that al- supply-oriented, top-down way in which water has traditionally lows for experimentation, course correction, and adaptation: been made available to them, with its rigid irrigation schedules, misaligned incentives, oversimplified distribution processes, and typically inefficient operation. 9 The concept of a sandbox alludes to an isolated testing environment in which novel and investigational concepts can be tested safely, without Sometimes, adopting I&M initiatives provides a rapid leap real-world consequences. Sandboxes could be in the form of challenge funds, innovation labs, hackathons, or seed funding for open-ended, un- forward toward the use and integration of modern technology. defined explorations of innovation led by various stakeholders (university More often, however, I&M takes the form of gradual and iterative teams, start-ups, or non-governmental organizations). 12 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE This is followed by a second rigorous step of assessment and understanding of the problems to be solved. The process then proceeds iteratively (in small steps and by trial and error) by keeping the horizon in view without losing sight of the small, intermediate steps. Much I&M is therefore a matter of painstak- ing education and awareness, well-informed trials with locally modified approaches (that have been successful elsewhere), systematic progress, and persistent determination rather than the deployment of dazzling technological breakthroughs. Equally, it may stem from legal or institutional reforms rather than the discovery and implementation of new technologies or their management by operators and farmers. The sustainable use of water and soil resources in irrigated agriculture cannot be ignored in this process, but is not the therein lies the source of innovation. The entire I&M process subject of this guide. works toward an overarching objective of modernization with Setting I&M Objectives and Choosing a systems orientation. I&M is thus a learning experience, with Appropriate Options the lessons folded back into individual I&M processes and disseminated broadly to inspire and guide parallel processes Multiple options exist regarding the level of water service de- elsewhere. livery that can be provided by an I&D scheme to farmers. Each option holds both advantages and drawbacks in terms of flex- The Step by Step I&M Process ibility, reliability, convenience, and cost. Within large, complex schemes, changes may need to be made within an integrated The I&M process is often gradual and iterative. Regardless of framework (that considers the landscape, catchment, and the approach that is ultimately adopted, the process starts with basin levels); but the need for step-by-step measuring, learn- increasing the awareness of key stakeholders so that they ing, and adapting still applies. are informed of possibilities for improved I&D as well as of the particulars for successful implementation of infrastructural and Simple modernization can often achieve excellent results. The management tools. main concepts, building blocks, and techniques of I&M in I&D INTRODUCTION 13 have been proven and tested. Information on what works well involves an entire value chain ecosystem, any part of which is already available, and great results can often be obtained can undermine the overall objective if not functioning well. with relatively simple measures. The more sophisticated the hardware, the higher the chance of failure if a requisite en- I&M is primarily about farmers as customers—and, potentially, abling environment does not exist.10 wise stewards of limited land and water resources—and must, therefore, engage them as full partners. Yet, beyond farmers, Success also requires stable, well-paid, well-educated, prop- I&M also needs to balance and, ultimately, reconcile numerous erly trained, and motivated staff who spend significant amounts and often divergent individual, collective, and public interests of time in the field. This involves building in-country expertise by carefully weighing trade-offs and setting incentives. to ensure sustainability of donor-funded interventions through a long-term engagement. I&M, properly implemented, is therefore about much more than water service. It involves maintaining communication Successful I&M also requires the considerations of real-world with multiple interest groups and solving challenges related economic constraints. It is critical to identify the level of mod- to environmental impact, social equity, climate change, and ernization that can provide the service level or performance financing, among other priorities. in the field that the scheme operator or farmer can manage affordably. After identifying the ideal options for modernization, In addition to farmers who are well informed and empowered performance diagnostics are undertaken as the starting point to make key decisions that affect them, other trained, moti- of a subsequent planning process. vated, and informed stakeholders are essential to the success of I&M—particularly off-farm irrigation scheme operators. There I&M to Whose Benefit? Incentives and Trade-Offs is a vital need for qualified and experienced advisors to ensure adequate implementation, and for government departments While an overriding purpose of I&M at the off-farm I&D system to support their work by creating a learning framework and level is to provide effective water service to farmers, farm- results-oriented policy that allows for capacity building and ers also need to be able to make optimal use of the water institutional development that results in piloting, course correc- provided. In addition to using appropriate irrigation practices, tion, and scale-up as part of a multi-phase approach. this involves incorporation of sustainable agronomic principles that enhance soil health and, thereby, ensure greater water use efficiency and productivity. Furthermore, I&M is necessary 10 Moreover, one must be careful when implementing new technologies. The not only at the farm level but also to better support agricultural prior successes in their use may have depended on the presence of a strong networks, markets, and finance. Growing and selling crops institutional structure that may not yet exist in a new project area. 14 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE A Limited Remit The guide’s audience includes World Bank task teams, irrigation service providers and scheme operators, stakeholders in govern- ment, and various other decision-makers, such as irrigation and Although I&M in I&D takes place within the wider context of agriculture agencies and development organizations, as well as ir- management and governance, this guide is limited to the tech- rigating farmers and their organizations. The guide also provides an nological aspects. Management and governance in I&D are entry point into a detailed repertoire of technological I&M solutions covered in the following sister publications: organized in a series of technical fiches, attachments, and country n Governance in Irrigation and Drainage: Concepts, Cases, case studies. and Action-Oriented Approaches—A Practitioner’s Resource, a 2019 World Bank publication that covers I&D sector governance. Organization of this Guide n The Irrigation Operator of the Future Toolkit, a 2022 The guide explains the primary drivers of I&M in I&D, its basic tools, World Bank publication that addresses the systematic and how they can be applied. It is organized into four chapters. diagnostics of irrigation scheme performance and con- straints and covers irrigation scheme management and management-level solutions. Chapter One: Defining the Nature and Purpose of I&M in I&D n The Farmer-led Irrigation Development Guide: A What, Why and How-to for Intervention Design, a 2021 World Chapter One provides an overview of the rationale for undertaking Bank publication focusing on modernization for small- I&M, its objectives, and the need to institutionalize it by embedding holder irrigating farmers. and integrating it with multiple levels of the local political economy. Chapter Two: The ‘Why’ Purpose and Audience Chapter Two examines a range of stakeholders in the I&D sector This guide was written to document the process of I&M in I&D and how each can benefit from I&M interventions. At the level of and the wide range of technological improvements that could irrigation schemes and their managers, the core driver of mod- help energize the irrigated agricultural sector globally. In a ernization is the need to deliver water to farmers in a controlled, world where fresh water is increasingly a scarce commodity, a efficient way. At the farm level, farmers, faced with new challenges modernized irrigation sector could help respond to current and and opportunities, are motivated to innovate and modernize to sus- emerging water challenges and market opportunities, while tainably improve their bottom lines and ensure the longevity and adding economic, social, and environmental value. sustainability of their farming operations. INTRODUCTION 15 Chapter Four: The ‘How’ Chapter Four examines the practical steps entailed in adopting I&M at the level of each of the three main stakeholder groups: farm- ers, irrigation managers, and policy makers. The first section, I&M Planning at the Scheme Level, discusses how I&D service providers can translate principles of service delivery into specific I&M plans to ensure that they continue to deliver the intended outcomes. This is pursued along with aligning stakeholder incentives with I&M plans. The second section, I&M at the Farm Level, examines how farm- ers can select and implement new technologies to help optimize their production processes. The section discusses the enabling At the policy level, the motivations for I&M are often more com- environment needed and lists the essential conditions for farmers plex, considering the wide range of socioeconomic, fiscal, and to plan, implement, and operate the innovations they have adopted. environmental objectives inherent to the I&D sector. Altogether, Farm-level I&M may consist of overall improvement to their on-farm the challenge is to identify I&M solutions and tools that best fit irrigation systems or simply making better use of an existing water the interests and motivations of all three stakeholder groups— service. The section concludes by examining the role of govern- farmers, irrigation scheme managers, and policy makers—to ments in supporting farmer-led I&M. deliver precise volumes of water to farmers in a flexible, re- The final section, Promoting I&M at the National Level, considers sponsive, equitable, affordable, and efficient way. how countries can develop a framework that encourages modern- ization and integrate modernization into national irrigation planning, Chapter Three: The ‘What’ as well as examples from various countries over the last 20 years. Chapter Three provides an overview of the range of I&M so- Ý lutions available and illustrates how they may help meet the objectives of farmers, irrigation scheme planners and manag- As supplement to the main text of the four chapters, technical fiches ers, and policy makers. The solutions described provide a menu appended to this guide provide supporting details. A guide to the of options from which modernization programs can be con- terminology employed (with linked references) is also annexed. structed. The accompanying fiches (with summaries of essential information on technical interventions) introduce very specific elements that can be utilized in the modernization process. 16 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE CHAPTER ONE Defining the Nature and Purpose of I&M in I&D DEFINING THE NATURE AND PURPOSE OF I&M IN I&D 17 The I&M Mindset What does innovation and modernization mean in the context of irrigation and drainage? It is a systematic, solutions-driven process by which technological and management improve- ments, pursuing an overarching objective, are adapted to the local context, and incorporated into irrigated farming. I&M pur- sues a systems orientation, with an understanding of how the various parts will work together to arrive at a desired result. I&M arises from a mindset and willingness to engage in bot- tom-up experimentation. It not only breaks with convention, but manages to avoid becoming paralyzed by skepticism, neutralized by complacency, or negated by risk aversion. I&M can take a multitude of forms and need not be a technological paradigm shift or a massive engineering revolution—although it can be. An innovative technology may be an adaptation of existing methods or a radical departure from them. It may be a leading- edge technical solution developed by scientists and engineers, or something that started off as an ad hoc arrangement with which local farmers or scheme operators came up. Either way, the process of innovation is essentially that of deliberate learn- ing that takes the status quo as a point of departure. In practice, this means that I&M must be a systematic, objective- setting process that keeps stakeholders’ eyes on the horizon, yet at the same time offering a safe, experimental environment that makes room for learning and adaptive management. Each The innovation process need not be complements the other in unlocking a dynamic process of a technological paradigm shift or a improvement. massive engineering revolution. 18 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Typical Objectives of I&M Improved water service delivery enables farmers to I&M in I&D includes both on- and off-farm solutions. Good intentions, optimize production hard work, significant planning effort, and worthwhile objectives for and increase their income. I&D scheme improvements are essential but insufficient in and of themselves. The proper options for modernization must be selected along with other beneficial and sustainable interventions. A significant and commonly encountered bottleneck to proper selec- tion and application of technical and management I&M measures in existing I&D schemes (combined on-farm and off-farm) is often the lack of knowledge of possible choices that are available for such measures. Such knowledge includes information on the advantages and disad- vantages of each option and its suitability and fit to a specific context.11 Successful I&M represents a process, often continuous and long-term, of adapting to and overcoming current and evolving constraints—such as mismatches between water service provision and farmers’ chang- ing needs—to reach defined objectives. But what are some examples of those objectives? At the off-farm scheme level, the objective of I&M is to im- From the farmers’ perspective, a major objective is to increase the prove water service delivery to farmers so that they can efficacy of every drop of water that reaches the farm to optimize crop receive the right amount of water at the needed time and production and increase income. Typically, this means a steady transi- at a price they can afford, and to drain excess water from tion away from the top-down, supply-driven management of irrigation fields. The irrigation service must also align with environ- to one that is responsive to farmers’ requests (e.g., for variable timing mental boundaries of the surrounding catchment or basin. and flow) and to their evolving needs. I&M therefore requires a sustained process of technical and managerial upgrading that goes beyond mere rehabilitation of underperforming old infrastructure. It emphasizes effi- 11 For off-farm interventions, simple and effective I&M measures often include the cient, responsive service provision enabled by the rational, modification and trialling of simple canal control structures. On-farm, it has been found that good land preparation practices (e.g., leveling and ensuring soil health) sustainable use of physical (including natural) and financial are the first step for improved application of surface irrigation. resources over the long term. DEFINING THE NATURE AND PURPOSE OF I&M IN I&D 19 CHAPTER TWO The ‘Why’ of I&M in I&D 20 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The goal of a modern irrigation system is to apportion, distribute, and deliver water in an accurate, equitable, and efficient way that enables farmers to control the quantity and timing of application of water in accordance with crop water requirements. This chapter presents the rationale for undertaking I&M, including its various drivers. The Problems to be Solved While there is no doubt that improved on-farm irrigation water management is important, the off-farm water conveyance and distribution systems often have serious problems. Poorly function- ing off-farm irrigation systems can lead to poor delivery of water to farms and, hence, losses in market value of crops and farmer incomes or crop failures. The reality for many irrigation schemes Delivering water to farmers in an accurate, worldwide is that water is delivered to farmers in an inequitable, in- equitable, and efficient flexible, and unreliable way, utterly incompatible with good on-farm manner is a key water management. objective of modern I&D. These inefficiencies also have serious socioeconomic and environ- mental consequences. Inefficiencies in the off-farm water delivery systems cause a variety of regional and local problems, such as The Goals to be Attained salinization of soils, waterlogging, and excessive diversion from riv- through I&M ers (causing environmental problems). Other challenges are posed by the effects of water storage solutions, such as the construction Modernizing irrigation schemes, with the aim of improving re- of dammed water reservoirs and overabstraction of groundwater. source utilization and water delivery to farms, offers an avenue And in cases where electricity-powered pumps are used in irriga- for providing a high level of service to all water users with an tion schemes, the inefficiencies in water management can translate objective of enhancing agricultural water productivity on farm. into inefficiencies in energy consumption. Another important ineffi- Delivering water in an accurate, equitable, and efficient man- ciency factor for productive use of water on-farm is lack of adequate ner is a key objective of modern irrigation schemes, impacting agronomic practices that help conserve the water delivered as soil the productivity of water provided to farmers and ecological moisture. outcomes. THE ‘WHY’ OF I&M IN I&D 21 A well-designed irrigation scheme controls the frequency, flow rate leaching (deep percolation) of fertilizers and pesticides into (or discharge),12 and duration of water delivery at every level (primary, groundwater and downstream flows. secondary, and tertiary) of the system to improve the reliability, equity, and flexibility of water services delivery to farmers. Much of the water losses in irrigation schemes occur at the off-farm level. The Drivers of I&M Some of the key aims of improved service delivery to farms and of One of the main drivers of modernization in irrigation is the on-farm irrigation systems (along with agronomic management prac- growing global demand for food and fiber as well as the tices) are to (i) increase yields and improve crop quality, (ii) conserve need to reform irrigated agriculture for more environmen- water, soil, energy, and other input requirements, (iii) reduce non-point tally sustainable production. Already central to meeting source pollution from agriculture, and (iv) provide better livelihoods the world’s needs, irrigated farming will play an even more for farmers and those supporting local agriculture as well as wider crucial role in delivering the levels of food production and societal benefits of food security. agricultural value-added that societies will need in the future Higher irrigation efficiencies can also reduce pumping costs and ener- within ecological bounds. Irrigated farming, done well, can gy consumption in some schemes. Moreover, in many large irrigation serve as a prime source of economic growth in rural areas schemes, the inefficiencies (e.g., in the form of leaks that drain into by increasing farmers’ incomes, offering employment, and water bodies via subsurface or surface flows or are lost to evapora- reducing poverty while providing significant multiplier values tion) may render applied water unavailable for further immediate use. Valid justifications for investing in improved irrigation systems and their 12 Flow rate specifies volume of water over time and is measured either in liters per minute or in cubic meters per hour. management also include increasing farm-level irrigation efficiencies. Improved efficiencies—frequently, but not always—result in reduced Barring farmer’s expansion of irrigated areas that would render real 13 water savings obsolete. water applications to individual fields13 and lower non-beneficial loss- es.14 Moreover, increasing on-farm water management efficiencies and 14 This typically means less groundwater or river extractions. For ex- ample, lower flow rates diverted at river diversion points (because of productivity is not limited to irrigation interventions but should ideally improved on-farm efficiency) often provide two large benefits: (i) more be coupled with agronomic practices that conserve soil moisture and water stays in the river for environmental flow requirements, and (ii) find synergies with other farming inputs. lower levels of sand or silt brought into the project canals. Regardless of the goals of improved irrigation, it almost always pro- 15 Excess deep percolation due to low on-farm irrigation efficiencies can create high water tables, which both damage crop roots and prevent the vides benefits beyond those accrued in individual irrigated fields. leaching of accumulated salt from root zones. These include improved water table (groundwater level) manage- 16 While such drainage water may be reused by downstream irrigators, it ment,15 reduced drainage water disposal on a scheme level,16 and less is almost always of a lower quality. 22 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE of the benefits arising from irrigated agriculture to non-farming greater output of these higher-value crops that typically require sectors.17 flexible, responsive irrigation services and higher water inputs. In many countries, private irrigation and irrigated agribusiness On the supply side, several disturbing trends related to climate are growing rapidly. Simultaneously, collective irrigation schemes change are on the rise. Water scarcity and variability are ob- are substantially contributing to rural economic development and served through higher temperatures, less predictable patterns stemming migration to urban areas. Increasingly, both farmers of rainfall, longer, more severe, and more frequent droughts and and policy makers around the world are recognizing that mod- floods, and greater aridity. In many regions, such climate trends ernized, innovative irrigation schemes are the engine that can have not only triggered greater variability in water supplies, but help catalyze poverty reduction through these macro develop- reduced their volumes. Much of the negative impact is also driv- ment trends and slow down rural migration to urban areas. en by unsustainable agricultural practices. The world’s land area equipped for irrigation reached 349 mil- Currently, some 1.2 billion people live in water basins where hu- lion ha in 2020, which represents an increase of 20 percent from man water use has exceeded sustainable limits. Environmental the 289 million ha reported in 2000, and more than twice that impacts are enormous; many major rivers around the world now in the 1960s (FAO 2022 Statistical Yearbook).18 Even so, to put run dry for many months of the year. And although groundwater matters into perspective, irrigated land accounts for only 20 per- in recent years has provided a vital source of irrigation water— cent of the world’s cultivated land—meaning that 82 percent of about two-fifths of the total—many aquifers are becoming acutely cultivated land is not rainfed (Borsato et al 2020). depleted due to over-abstraction. Improved allocation and man- agement of water resources is imperative in such circumstances. In addition to growth in demand for food and fiber, a second driver of I&M in I&D is the changing pattern of demand for agri- cultural products brought on by rising prosperity. The demand for high value produce such as fruits and vegetables, which do best when grown under irrigation, is fast expanding. Farmers are finding that they need more finely controlled irrigation to provide With irrigated agriculture 17 For example, irrigation serves as a powerful means of reducing food costs as the world’s largest and supports agro-food industries in rural areas that may otherwise be subject freshwater user, the to out-migration to urban areas. rising demand for the 18 Most of the land equipped for irrigation is in Asia (70 percent), with largest resource cannot be met areas being in China (75 million ha) and India (73 million ha). without I&M in I&D. THE ‘WHY’ OF I&M IN I&D 23 In the face of diminishing water supplies and a growing world The answer is not for farmers population, the rising demand for water cannot be met without to use more water, but to use it more efficiently and I&M in I&D. Irrigated agriculture is already the world’s largest productively. user of water, accounting for 70 percent of freshwater withdraw- als worldwide, and more than 90 percent in some countries with very dry climates. Additionally, the pressure on water resources is intensifying partly because, as economies develop further, other water- using sectors—some of them newly emergent—are increasingly competing for the same water that irrigating farmers need. With the non-agricultural demand for water rising rapidly, the pres- sure is increasing in many water basins to reduce water use to more sustainable levels to restore environmental flows and revive the ecology that sustains these water sources. For farmers, who are faced with rising demand for high-value crops and a diminishing natural resource base, the answer is not for irrigated farming to use more water but rather to use it more precisely and efficiently. Hence the need to innovate and modernize existing and new I&D schemes. Finally, there is also an important “push” factor that is accel- erating I&M in I&D. In many advanced economies, emerging technologies have created an impressive range of innovations that can be applied in the I&D sector. Some have been available for many years but are yet to be widely adopted, particularly in developing countries. It should, however, not be taken for granted that I&M will hap- pen on its own, regardless of the choices made and availability of an enabling environment. The drivers of I&M need to be rec- ognized and harnessed to explore their full potential. 24 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The Opportunities and The reasons why I&D schemes may fall short of expectations and un- derperform are varied. There could be flaws in the system’s original Challenges Facing I&D Today design, or its management, operation, and maintenance (MOM). A combination of aging infrastructure, institutional problems, inadequate The I&D sector has reached a historic window of opportunity skills for MOM, and/or underfunding may also be present. shaped by a massive challenge: the rapidly growing patterns Accordingly, many existing irrigation delivery structures cannot of demand for food and fiber that must be met using con- respond to recent changes in farmers’ demand patterns. Merely strained—sometimes shrinking—water and soil resources. Put distributing irrigation water throughout a scheme is increasingly inad- simply, the challenge is to obtain more crops and value from equate for providing farmers with the reliable and flexible service they less water, and it demonstrates why I&D needs to innovate need to update their on-farm irrigation techniques, cropping patterns, and modernize in a sustainable manner. Broadly speaking, and agronomic practices to generate higher yields and more value. I&M can help farmers—and national economies—get more from less while staying within the bounds allowed by natural The I&M of hydraulic infrastructure and equipment can offer solu- ecosystems and the valuable services they provide. tions to these challenges. Through I&M, many existing I&D schemes can become more responsive to farmers’ needs by becoming more A key question here is how this translates into specific demand-oriented, flexible, and efficient. Whatever the history of the objectives, incentives, and stakeholder motivations. This scheme and the nature of local constraints, there is an extensive section examines the opportunities and constraints that cur- rently face the irrigated agriculture sector, and the stimulus these opportunities present to I&D scheme managers, farm- ers, and policy makers to embrace I&M. The following three subsections provide an overview of the objectives of I&M, along with the challenges and opportunities for its adoption, from the perspective of each of these three actor groups. The Irrigation System Manager’s Perspective Although the basic challenge at the irrigation scheme level is to deliver reliable water service that responds to farm- A wide range of innovative ers’ needs, many such systems fall short of this fundamental technologies is available to design objective. As a result, the productivity of millions of improve water delivery to farms around the world cannot effectively meet demand. farmers. THE ‘WHY’ OF I&M IN I&D 25 range of innovative, tried-and-tested technologies available n Increasing operational income to cover costs through techni- to improve water delivery service to farmers. cal innovations in water supply metering and payments, advisory services, multiple-use schemes, or reducing lost (non-revenue) It should also be borne in mind that great technology does water. With lower costs of scheme’s operation and higher farm not function in a vacuum. Technical I&M solutions work opti- incomes, service fees can be set at a level that covers the costs mally only when they are supported by, and integrated into, of running the system while remaining affordable for farmers. a broader framework of sound management and national governance aimed at achieving long-run sustainability, social n Strengthening the resilience of I&D systems and reducing equity, and the careful application of non-distorting incen- negative environmental and social impacts, such as resource tives to guide and motivate the right behaviors and practices. depletion and pollution, by increasing the efficiency and stew- ardship of natural resources. Such a macro framework needs to be based on a close col- laborative partnership approach that aligns systemic changes with farmers’ and environmental needs, climate trends, Box 2.1 Evaluating Water Service Delivery: Seven and long-range development objectives and projections. Tests of Its Performance Quality19 Ultimately, much of it comes down to how strongly the major actors within the national space desire change in the perfor- n Adequacy: Is there enough? mance of the I&D sector, and have the capacity and financial n Reliability: Can we depend on it? resources to create an enabling environment to implement the main tenets of I&M. n Equity: Do all users receive their fair share? n Flexibility: Can the service accommodate relatively sudden Supported in this way, I&M can help I&D service providers changes in demand? working with farmers to achieve several vital scheme-level n Productivity: Is the service responsive to trends in agricultural objectives: production? n Increasing the reliability and flexibility of water de- n Operability: Is the scheme in good working order? livery to farmers, while improving access, equity, and n Multiple-Use Services: Are the needs of other rural water users inclusion in service provision (Box 2.1). also met? n Improving the efficiency of service delivery in terms of Adapted from Waalewijn, P., R. Trier, J. Denison, Y. Siddiqi, J. Vos, E. Amjad, 19 costs and effort, reducing water loss and the unneces- and M. Schulte, Governance in Irrigation and Drainage: Concepts, Cases, and sary consumption of energy, addressing overstaffing, Action-Oriented Approaches—A Practitioner’s Resource (Washington, DC: and implementing better targeted irrigation asset man- World Bank, 2019), https://openknowledge.worldbank.org/handle/10986/32339. agement plans. 26 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The Farmer’s Perspective On-farm irrigation systems that are supplied by off-farm schemes are completely dependent upon the quality of water service deliv- Present-day farmers have major prospects with modernized and ery provided by the off-farm portions of irrigation systems. Hence, innovated I&D systems but face significant challenges in lever- an irrigation service that does not provide water to farms in predict- aging or benefiting from these opportunities. Today’s globalized able, timely, and adequate quantities is eliminating opportunities food markets—increasingly shaped by health-conscious, well- for increased yields, more diversified crop production, and higher, informed consumers who demand an ever-greater array of more secure incomes. higher-quality food options—require greater volumes of diverse staples and high-value crops as well as higher standards of Ultimately, a farmer’s perspective rests on their bottom line: in agronomy for improved food safety and nutritional value. reducing their crop cultivation costs—particularly the cost of I&D service delivery to the farm, on-farm I&D technology, and other in- For irrigating farmers, participation in new, more complex agricul- puts required to work the land. I&M of both off-farm water service tural value chains promises better incomes. It also requires them delivery and on-farm I&D systems can help reduce costs of produc- to grow crops of higher quality, which in turn demands reliable, tion and boost profit margins by improving system performance, flexible, and affordable water service delivery to appropriate, on- raising efficiencies, and providing irrigation management that farm- farm irrigation systems that use water efficiently and effectively, ers need to meet their changing needs. along with regenerative agronomic practices that maximize pro- ductivity while safeguarding the natural resource base. The Policy Maker’s Perspective I&M of I&D systems can help attain national objectives of economic growth, food security, and resource-use efficiency. Of the three ma- jor stakeholder groups, policy makers are the only group configured to view the benefits of I&M for the I&D sector from an aggregate national perspective. There is an orchestrating role for national leadership to play to better integrate the interests of all groups and align relevant incentives in an efficient and cohesive way. Considering the governance systems in place, policies adopted, and resource allocation decisions, I&M can help create a more effi- I&M can help farmers reduce the costs cient, productive, and profitable agricultural sector characterized by of production and higher output, greater value-added, and (potentially) increased ex- boost profit margins. ports. However, the strain on the public sector’s fiscal resources—in THE ‘WHY’ OF I&M IN I&D 27 I&M of I&D systems can help attain government support. For example, such changes can generate a national objectives of economic higher economic return on I&D investments, increase the sector’s growth, food security, and creditworthiness for commercial finance, and increase the overall resource-use efficiency. financial capacity of the sector. All of the above-listed factors can further boost and sustain a high technical performance in off- and on-farm I&D systems and longevity of farming operations. However, given the semi-public good characteristics of irrigation service provision (due to its socio-economic benefits), the need for carefully targeted government support to I&D is immense and may not be fully eliminated even with increased investments in the sector by farmers and private business. For instance, many of the forces external to irrigated agriculture, such as those related to growing needs for urban water supplies and environmental res- toration, are beyond the ability of the sector to respond to and require the engagement of the public sector. Moreover, in many locations, more efficient21 and profitable irrigation could promote a shift away from “subsistence” farming—traditional farming centered on the narrowly framed objective of achieving investing in the construction of new I&D schemes as well as en- food self-sufficiency—and toward a more market- and (partially) suring their modernization and rehabilitation—has been great.20 export-oriented agriculture sector that aims to achieve both profits A modernized public irrigation sector would contribute to high- and long-term food security. The added benefits may include keep- er economic returns on public investment and make possible ing food prices affordable and providing incentives to youth to earn more efficient use of fiscal resources by way of increased farm a livelihood from farming. profitability. As a result, farmers may be enabled to pay higher water delivery fees, thereby augmenting the financial autonomy of I&D scheme operators and water user organizations and re- 20 In many parts of the world, developing new water resources for irrigation has ducing the need for government subsidies. become very expensive. 21 Even in places with diminishing water availability for irrigation, increasing the A more profitable agriculture sector would also encour- efficiency of water use in irrigation can help sustain a vibrant irrigated agricul- age private investment in I&D while reducing the need for tural sector by providing more value per drop of water consumed. 28 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Furthermore, a modernized irrigation sector holds the ability to Prudent development of use water and land resources more sustainably, particularly if im- irrigation can help mitigate the economic impacts of proved I&D management promotes resource conservation and climate change. helps sustain the local ecosystems and their biodiversity. I&M can also strengthen water security by enabling the best and most efficient use of water resources in irrigated crop production through use of innovative technology for monitoring and decision- making. This can occur in several dimensions. At the basin level, water security can be strengthened by adopting a more sustain- able approach to the development, allocation, and management of water resources to meet the changing patterns of demand from irrigation, other water-using sectors,22 and environmental needs. This also applies to reducing the over-abstraction of groundwater. Groundwater depletion is a global phenomenon that has become a major concern, first because it is reducing a strategic reserve of water for future generations and, secondly, because groundwater offers a first-rate buffer to which farmers can turn as a last resort in responding to water shortages, either due to service delivery issues or those growing increasingly severe with climate change. Lastly, prudent development of I&D can greatly mitigate the im- pacts of climate change on the overall economy, making the best In conclusion, there are good reasons for all three of the main use of diminishing water resources, smoothing out water availabil- I&D stakeholder groups (irrigation system managers, farmers, ity (particularly as rainfall becomes more erratic), meeting higher and policy makers) to engage in I&M of the sector. These mo- crop water demand as temperatures rise, sustaining farming in tivations can be summarized as deriving more value from less areas of increasing aridity, and improving drainage in flood-prone water—within constraints. areas. The next chapter examines the range of I&M options avail- able—the ‘What’, while the final chapter, which looks at the ‘How’, 22 Moderating the consumption of water in irrigation can make more of it avail- describes some practical steps that each of the three stakeholder able for other uses—municipal, industrial, and environmental. groups can take to adopt I&M. THE ‘WHY’ OF I&M IN I&D 29 CHAPTER THREE The ‘What’ of I&M in I&D 30 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE This chapter presents an overview of the main com- ponents of I&D schemes and the available range of I. System Level Structures and I&M tools. It also discusses how farmers, irrigation scheme planners and managers, and policy makers Operation Approaches could leverage these tools to meet their respective Irrigation Water Control objectives. The I&M solutions described here essen- tially offer a modular menu of options from which a To meet any or all three objectives of good water service—reliability, equity, modernization program may be constructed. and flexibility—the operators of irrigation systems must have control of water flows and levels. For the purposes of operating a scheme, operators must The chapter begins by describing the key strategies control how, when, in what quantity, and at what pressure water is delivered and structures for operating the off-farm (or system to farmers. Different levels of water control will deliver different levels of water level) portion of irrigation schemes. It then moves service. onto the range of off-farm I&M tools and options at the level of the system down to, but not including, the farm level. In the final section, the chapter describes I&M tools and options for on-farm use by farmers. Further details on various topics referenced within these sections are provided in a series of technical fiches appended to this volume. It is also important to note that technological innova- tion by itself is not enough to improve the performance of I&D systems, but must be coupled with enhanced system management as well as appropriate farm-lev- el agronomic practices and the management of the surrounding landscape (to minimize catchment-level impacts on water and land resources). Moreover, system management arrangements must be compat- ible with the engineering choices made and ensure Irrigation system operators that necessary skills, incentives, and motivations are use hydraulic structures in place. This may necessitate capacity development to control flow rates and to ensure the uptake of available knowledge. water levels. THE ‘WHAT’ OF I&M IN I&D 31 Water control is enabled by hydraulic (or regulating) structures Selection of the regulating structures for water control will depend that serve two functions—flow rate control or water level con- on the choice of a system’s configuration and control strategy (or trol (or pressure control in piped systems)—and are crucial for mode).27 Two of the most common modes of hydraulic control or every level of the irrigation water supply system. Flow control control strategy are upstream and downstream control (i.e., supply- is used to attain target water levels either upstream or down- or demand-oriented).28 Under upstream control, the flow of water stream of a regulating structure. It enables operators to adjust (or discharge) is controlled from the top down at each hydraulic the flow rate to equal a target value.23 Control of water levels level (or layer) throughout the system, while water levels are con- is typically achieved by operation (or movements) of various trolled at the downstream end by regulating structures. Upstream water control structures or regulators that minimize water-level control requires strong central management and does not permit fluctuations at a specified point. much flexibility in water use on-farm.29 Regulators for canal water flow and level control include gates24 and weirs. Gates are situated at water delivery points 23 In the past, it was sufficient for irrigation service providers to deliver a constant (also called turnouts or offtakes) and represent a point at which flow rate—also known as the uncontrolled continuous flow. With an increasing de- control of water changes from the service delivery entity to end mand by modern-day on-farm irrigation for a variable flow (as required by crops), farmers require greater flexibility in flow rates as dictated by the type of on-farm users [Fiche 3.3: Canal Gates].25 Weirs represent cross struc- irrigation systems used. Operators also need to know the flow rate at each gate tures that are typically installed to maintain a constant water to better operate the system. level upstream or downstream of their location.26 24 Various types include regulator gates, slide gates, radial gates, or flap gates. 25 Gates may be operated manually, hydraulically, or by using power (motorized), Gates and weirs are and can be controlled either locally or remotely. More specifically, regulation can common water flow and be achieved (i) manually by a human operator, (ii) by the water forces on a hydro- level control structures. mechanical gate, or (iii) electro-mechanically. 26 Stable water levels, hydraulically regulated upstream, result in constant discharges in offtakes. 27 The water control strategy chosen will depend on multiple factors, such as (a) water resources availability and their sources (surface or groundwater); (b) types of crops served and their level of diversity; and (c) topographic elements of the area served and soil types. 28 Others include mixed (or composite) control; volumetric control; and centralized control. Most control strategies include aspects of both supply- and demand- oriented systems, since a combination of these control systems may lead to an optimum control method. These can be manually operated or automated. 29 Most irrigation systems worldwide still operate through upstream control. 32 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE In contrast, downstream control means that the water discharged demand-scheduled system, water supply is controlled from the in each reach30 is controlled from the downstream end. In such bottom up by farmers, thereby accommodating (to the extent cases, changes in flows emanate from the tail-end of a scheme possible) their individual needs.35 However, full demand-based and sequentially work upstream through the system. A major ad- irrigation is very rare. vantage of downstream control is its short response time, offering Arranged (modified- or semi-demand) scheduling is commonly a higher degree of flexibility (allowing for a more demand-based used in larger irrigation schemes and provides some degree of water delivery). The ultimate selection of an operation method of self-management by farmers or their water users associations I&D schemes is closely associated with the irrigation scheduling required, as discussed below.31 Irrigation Water Delivery and Scheduling 30 Reaches are structures for conveyance and/or storage of water. In canals, reaches are separated by cross-regulators, and in the case of pipelines, by pressure-controlling valves. On-farm irrigation water scheduling is only possible when a de- livery system provides irrigation water at the expected time, rate, 31 Irrigation water delivery system management deals with matching the inflow- ing water discharges (from the source) with the outgoing discharges. Typically, and duration to end users. There may be several different modes there are two types of delivery system management: central and responsive of water delivery at various levels along the system, as the vari- system management. Central system management is typically applied in ous levels may have greatly different priorities and management upstream controlled delivery systems and is found where the discharge objectives.32 from the water source must be matched with the required delivery schedule. Responsive system management is found in places where the delivery system Options for water delivery to end users follow a variety of irrigation itself adjusts to the changing outflowing discharges. scheduling arrangements. Similar to the overall irrigation water 32 Some levels may operate on supply, arranged, or demand schedules. control methods, delivery scheduling can be categorized as sup- 33 Very common to supply delivery are rotational schedules. They allow for ply scheduling, demand scheduling, and arranged scheduling. water to be fed down each receiving canal for a specified period and on a rotational basis. Rotations depend on the crops they serve, and can be set for With supply scheduling,33 water is controlled from the top down weekly, 10-day or bi-weekly deliveries. and canals are designed for upstream control, which is common 34 Protective and productive irrigation pertains to strategies applied during for large protective34 irrigation systems. It represents an inflexible their initial planning. They are aimed, respectively, at crop protection and crop production, and at financial benefits versus economic benefits. Protective system, using rigid supply delivery plans with little room for farm- irrigation is an older model that focused on keeping crops alive with the ers to deviate from pre-planned water delivery schedules. overall goal of food security. As part of productive irrigation, modern irrigation planning balances the costs of irrigation and intensive agriculture against the Demand scheduling has as its basis downward or downstream crop’s economic return, thereby looking for an optimum economic yield. control of canals or pipelines, whereby discharge is controlled 35 Delivery systems that are considered flexible are essentially downstream by the end user at the downstream end of the system. In a controlled, with deliveries scheduled upon demand. THE ‘WHAT’ OF I&M IN I&D 33 (WUAs).36 With arranged scheduling, delivery is based on pre-determined plans or records, whereby water can be Box 3.1 The Myth of Full Demand-based Irrigation obtained at any time,37 provided that it is requested in ad- Water Delivery vance. While presenting a more flexible delivery option, with farmers able to request water delivery at a chosen The idea of a demand-based delivery capability directly from a large time, arranged scheduling still utilizes upstream control. network of canals to individual farmers is interesting but impractical in most cases in the world. A true demand delivery to farmers would mean Delivery systems that are considered flexible are essen- that farmers could receive any flow they want, for any duration, at any tially downstream controlled and demand scheduled. The time—similar to opening a faucet at home. In reality, there are limits to more flexible and on-demand a delivery scheduling sys- the maximum outlet flow rate in a scheme ( just as with a home faucet). tem becomes, the more it can be considered crop-based. A scheme that provides on-demand delivery to farmers must have a However, certain aspects pertaining to demand-based completely flexible and large water source to supply large peak flow irrigation water delivery must be considered and are de- rates to individual outlets. Also, between the water source and the scribed in Box 3.1. fields, colossal pipelines or canals would be needed, because everyone might want water all at once—such as at planting time. Furthermore, With arranged scheduling, farmers demand automation of canals simply does not work in most canals, can request in advance for water to which have slope and do not have very low velocities. be delivered at a chosen time. It is true that many pipeline schemes do operate on a limited-rate demand schedule. The key ingredients are that the schemes are rela- tively small (to avoid huge pipe sizes); have very small hydrants (outlets or turnouts) with flow limiting devices that only allow small flow rates (which is only applicable for some sprinkler and drip/micro systems); require farmers to operate almost continually during the hottest months of the year; and have a very flexible water source. 36 WUAs consist of water users, such as irrigators, who collect fees, operate schemes, implement maintenance, handle disputes, and elect leaders, among other things. 37 An arranged delivery is usually required to start at a specific time to match the timing of canal operations. The flow rate made available to various turnouts can be different, and usually varies from one irrigation event to another for a single turnout. In practice, most irrigators use only one flow rate at a turnout. 34 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Water Measurement canals [Fiche 3.1: Off-Farm Pipeline Conveyance]. They are charac- terized by high water-use efficiencies due to negligible seepage Measurement of water in an irrigation scheme is as important and operational losses. Additionally, piped systems require less as its control. Effective irrigation water management begins maintenance than canals and tend to have a longer lifespan. with accurate water measurement, which represents a crucial However, they are susceptible to siltation40 and clogging. step towards ensuring that water is used efficiently and produc- tively [Fiche 3.2: Flow Measurement and Control to Outlets (in Drainage Canals)]. Measurement is also an essential tool for good on-farm water management, and can enable volumetric water allocation One of the key functions of drainage is to remove heavy rainfall processes if water service is sold on a volumetric basis. water from the soil surface before it has a chance to infiltrate and cause a root zone inundation problem. Where the natural drainage Surface and Piped Water Conveyance of cultivated soil may be inadequate and limit its useability, drainage processes can be accelerated through use of artificial drainage.41 Irrigation water conveyance and distribution can be divided into provision via canal (surface) and piped schemes. Surface Scheme-level drainage systems are required for several reasons. irrigation systems usually consist of a network of open canals Firstly, they pick up and dispose of surface drainage water from as the main waterways carrying water to farms. Common struc- the scheme that comes from heavy rainfall runoff from roads, cit- tures on canal systems include diverting structures at water ies, farms, uncultivated land, and so on. In addition, they pick up, delivery points, called turnouts, offtakes, or delivery gates.38 convey, and dispose of the on-farm drainage water. Drainage is also Turnouts typically enable (i) an ‘on/off’ control of water flow; (ii) frequently required to prevent waterlogging and soil salinization. flow rate control to adjust the flow rate; (iii) flow rate measure- ment; and (iv) volumetric measurement. 38 Surface irrigation structures can also be classified, in terms of the adjustments Operational water losses commonly occur in surface (or canal) that they allow, as (i) fixed (with no adjustments possible); (ii) gradual adjustment; irrigation networks during the delivery of water from a head and (iii) automatic. source down to farmers. Seepage and evaporation (along with 39 It is important to note, from a water conservation standpoint, that seepage and poor operation) represent the most common forms of water spill losses may be recovered downstream (or from well pumping) and do not represent basin-wide losses. loss in an irrigation canal network.39 However, it is common for appropriately modernized canal schemes to provide excellent 40 A piped irrigation network may not be suitable for implementation if local water delivery service directly to farmers. irrigation water contains large amounts of sediments; otherwise, desilting arrange- ments would be necessary in such cases. Piped irrigation systems have been gaining acceptance for 41 Drainage systems can either be constructed concurrently with an irrigation conveying and distributing irrigation water as an alternative to scheme or be deferred. THE ‘WHAT’ OF I&M IN I&D 35 II. Investing in Off-farm I&M When needed, engineering works dealing with I&M can en- able measurable volumes of water to be supplied to each Implementing I&M at system level is ideally undertaken as an itera- hydraulic level and management tier of a system. I&M also tive and gradual process, with the end goal of improved water service aims to make each level of a system as hydraulically inde- provision. This is perfectly compatible with a heuristic approach of incor- pendent as possible, so that each level can provide reliable porating adjustments and small improvements as needed. In fact, I&M and timely water delivery to the subsequent lower level. often takes the form of a progressive process of continuous learning by system operators and farmers alike, allowing for trial and error. Relatively The Nature of Off-farm I&M modest steps often suffice. Off-farm I&M focuses on how (off-farm) I&D schemes func- tion as a unit to provide water service to individual or small groups of farmers. It emphasizes how the total off-farm network functions together under very dynamic conditions on a minute-to-minute basis. I&M, if exercised properly, will show that there is no sin- gle best solution or combination of technologies for all irrigation schemes. The process often uses a mix of tech- nologies within a single scheme to provide the best and most economical water delivery service to the customers (farmers or WUAs). Different mixes of I&D technology are usually applied at different hydraulic layers.42 As an example, a combination of canals and pipelines may be available for off-farm water distribution. And the control of a canal scheme may be dif- ferent near the head of the canal as compared to its tail end. I&M often combines technologies within a single scheme to provide 42 For example, a hydraulic layer may be composed of a main canal, the best and most economical followed by a secondary canal, then a tertiary canal, then a pipeline water delivery service. scheme. 36 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The main challenge for any irrigation scheme’s improvement irrigation managers provide water to users in a flexible, reliable, and is to identify the level of modernization that would provide the equitable manner.43 required quality of water delivery service to the next-lower hy- Systems’ management arrangements must also be compatible with draulic layer in the network. There are often several technical the engineering choices, by ensuring that the necessary skills, ex- options that can achieve the same goals, although there may perience, and motivation of relevant staff are in place. This includes be vast differences in their cost, simplicity of implementation, capacity development to ensure the uptake of available knowledge. and ease of management. For example, when working with an existing irrigation system, The I&M Perspective automation of canal control systems represents one of the key tools for modernization. Automation allows for more flexibil- The entire I&M process is predicated on a mindset that is open to ity of operation to be built into a system and provides water innovation. Off-farm I&M is, first and foremost, about understanding users (irrigators) with improved flexibility of service for more the system and the process required to achieve improved water efficient on-farm use. By enabling improved control of flows, service. It is as much about staff outlook, capacity, and relevant canal automation has the potential to save water (and reduce changes in procedures as it is about innovative technical solutions. operational losses), thereby increasing the efficiency of irriga- In the infrastructural realm, modernization typically involves the as- tion water supply operations. Thus, canal automation can help pects of redesign, refurbishment, and sometimes automation44 of various parts of I&D schemes and their management. It differs from rehabilitation, which merely restores a scheme to its original design functions. It is also different from implementing piecemeal solutions that address only one component of a system. These are devoid of a clear vision of a wider objective or the range of applicable innova- tions, and how all the necessary components should work together as part of a dynamic system. System management 43 However, a very sophisticated automation network may be very expensive and arrangements must fragile. A simpler solution could make extensive use of regulating (buffer) reser- include staff with voirs. Buffer reservoirs are often constructed in each of the hydraulic layers. the necessary skills, 44 Automation requires superb design and maintenance and must be appropriately incentives, and applied, often in selected locations within a water distribution system. Simple local motivation. automation with remote monitoring has proven to be the most reliable option. THE ‘WHAT’ OF I&M IN I&D 37 Most of the main concepts, building blocks, and technolo- gies of I&M are well tested and proven. While there is always room for cutting-edge technology at the margins, the main challenge is to identify what type of I&M is appropriate to the scheme and farming systems in question, and to work out how best way to adapt it to the inevitably highly specific local context. Improving Water Control in Irrigation Water While rehabilitation restores a project to Delivery Systems its original functions, modernization moves Controlling water within an irrigation scheme is radically dif- it forward so it can ferent from, for example, municipal water supply. Irrigation meet new demands. schemes must deliver vast quantities of water—typically in the range of 10,000 m3 per hectare every year—to large num- bers of outlets. This requires massive investment in elaborate Almost all project-level investment programs consist of a mix of re- delivery systems capable of bearing enormous volumes of habilitation and modernization. Rehabilitation may be necessary for some aspects of a scheme served by a project. For example, there water, often over a hundred miles or more (potentially through may be failing diversion structures, or canals may be ready to col- a main canal that rivals a river in size), and then, with mod- lapse into a river. Rehabilitation just brings a project back to where it ernized schemes, sharing the water in a flexible, reliable, fair, can function as originally envisioned. In contrast, modernization goes and predictable way through thousands of smaller canals and well beyond rehabilitation and moves the project forward so that it pipelines to a myriad of users on a regular basis. can meet the new and future demands. Often modernization con- Moreover, high performance operation of such schemes is cepts can be incorporated into rehabilitation projects. complicated because small errors and variations are ampli- Embedded in the concept of I&D schemes’ I&M is the notion that fied over time and space. While everything happens in plain water should be delivered in a manner that it is manageable by the sight, there is often a lack of real-time monitoring over the ultimate customer (the farmer), so that the water applications are extensive water delivery networks and their delivery points. timed to match the crop requirements. This way, specific irrigation This, combined with inappropriate control and measurement events are determined by the on-farm irrigation system used, local structures, significant scheme maintenance issues, and a lack climate and soil type, variety of crops and their level of maturity, and of effective enforcement of rules, often results in a system so on—and there is no one schedule that matches all fields. that is vulnerable to tampering and diversion of water. 38 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Fortunately, many pragmatic options are available for improved Various control and measurement devices were developed to en- monitoring, delivery scheduling, and operation of canal and able flow rate control. Thus, modern irrigation schemes can divert pipeline schemes. Many modernized canal schemes operate water at a specified flow rate and distribute water at that flow rate with an excellent quality of service delivery to farmers (in terms to hundreds of different outlets of varying sizes, in an equitable and of flexibility, equity, and reliability) and high delivery efficiency transparent manner. The physical structures that enable flow rate (with little or no spill). control allow for modifications to water delivery by altering the rate, frequency, and duration of flow. For instance, in the foreseeable future, successful canal schemes’ modernization will improve their operation with im- In the end, most modernization projects must focus on what can be proved hardware and operating procedures. However, most realistically modified with the existing canal schemes—which might modernized main irrigation canals will continue to operate under include adding pipelines near the tail ends. When examining the upstream control—albeit with much better performance—due fiches on these topics, two ideas should stand out: to physical limitations, risk and cost considerations, and need for a flexible supply required for downstream control. With 1. Modern on-farm irrigation works very well with flexible arranged such control, water is released into the head of the main canal delivery schedules. In modern schemes, farmers or farmer based on arranged schedules of water delivery throughout groups request a specific flow rate for the next day. The water the system. Operators of each secondary canal then periodi- delivery operators check available capacity and available flow cally (typically several times/day) adjust and control the target rate and can inform the customer if they can satisfy the request. inflows based on the downstream requests and water orders, 2. Modern off-farm irrigation hardware and management solutions and so on downstream through the various branches. that can provide arranged delivery schedules are highly varied, Control Strategies and Hardware depending upon topography, sediment in the water, density of canals, available flexibility at the source, local skills, and so on. Flexible, reliable, equitable, and efficient operation of off-farm systems requires appropriate control structures at appropriate Modernization requires selection of the appropriate options. Details locations. An important first step in a successful off-farm irriga- are introduced in the various fiches, but typically a successful mod- tion modernization program is to select the control strategy ernization program will utilize a variety of technologies and control that will provide the desired results in a reliable and sustain- strategies at different hydraulic levels in a scheme. able manner and at a reasonable cost—all fitting within the Flow Measurement capabilities of the institutions managing them. I&M can im- prove water control and service in any of the three delivery In addition to control, measurements of water are needed at various options (discussed in Section I above) or allow a system to hydraulic levels by the irrigation scheme. Water measurement is used upgrade from one delivery schedule to another. to determine both total volumes of water and flow rates. Measuring THE ‘WHAT’ OF I&M IN I&D 39 flow is useful for estimating irrigation water use and Regulation Reservoirs within Canal Systems contributes to better management and scheduling of irrigation events.45 Flow rate measurements also help The actual flow rate may change every minute. Because of the varied times ensure that an irrigation system is operating properly required for flow changes to move throughout the scheme, unexpected and is not subject to breaks, leaks, or obstructions. weather, inaccuracies in flow measurement, and other reasons, one may Meanwhile, measurement of volumes helps in verify- find that the actual flow rate is not exactly what it should theoretically be— ing that a proper amount of water is applied at each particularly while moving down a canal scheme through its various levels irrigation event (at levels not exceeding amounts (primary, secondary, and tertiary). permitted). Flow and volumetric measurement also To convert this increasingly variable flow rate into a manageable, constant provide farmers with information that contributes to desired flow rate, it is common to use regulating reservoirs at strategic improving on-farm irrigation management. locations in the downstream reaches of canal networks [Fiche 3.4: Canal There are numerous ways to measure and control Regulating Reservoirs]. These are not storage reservoirs. They hold the dis- flow rates at the heads of canals and at field or water crepancies in target (versus actual) flow rates for a period of a day or so. In user levels [Fiche 3.2: Flow Measurement and Control other words, the flow rate fluctuations move in and out of the reservoir to to Outlets (in Canals)]. Flow measurement technolo- provide a constant, re-adjusted, and scheduled downstream flow rate. gies can be used as standalone (deployed at strategic sites), site management, or as network control solu- Canal regulating reservoirs tions (providing system-wide flow measurement). are an essential element in most I&M interventions. In some cases, advanced on-farm application sys- tems may provide the ability to measure flow rate and volume. For example, drip systems that are directly connected to a canal can control the flow rate. In such cases, the need at the outlet (the structure be- tween the canal and the field) is to provide an on-off capability, and to measure both flow rate and volume delivered. 45 Measuring irrigation flow helps irrigators in estimating irrigation water use, by letting them know how much water is applied dur- ing each irrigation cycle, and how much to pay in water charges. 40 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE These regulating reservoirs can be on the main canal, at the heads of small canals or pipelines, or even on individual Box 3.2 Off-farm Use of Pipelines for Water fields. They represent an essential element in most irrigation Conveyance and Distribution project modernization interventions. Although some land may need to be taken out of production by installing regulat- Pipelines have been used in irrigation projects for more than a ing reservoirs, the overall production and irrigation efficiency century. Advances in materials, designs, and new on-farm irrigation is increased in the overall service (command) area. methods have opened up new opportunities. Many of the older (very low-pressure) pipeline distribution systems Canal vs. Piped Irrigation Schemes were made of unreinforced concrete pipe. Eventually these systems began to suffer from extensive cracks, due to multiple variables As part of a modernization process, irrigation systems may such as exposure to cold water, heavy equipment loads, and land be adapted from open canals to pressurized (use of pumps) subsidence. As older pipeline systems are being modernized, plastic or gravity pipe systems. As large pipelines are extremely ex- pipeline systems are taking their place. pensive for both initial installation and the associated annual Pipelines are also widely used in irrigation modernization projects to costs, pipelines are typically used for distribution of water at replace a section of a canal or small canals because of their well-doc- the lowest end of the scheme, where the benefits related umented benefits—including low maintenance, no seepage or spills, a to control and maintenance are available at a relatively low quick hydraulic response (from the head to the end of a pipeline), and cost (because of smaller pipelines). the ability to cross variable topogra- phy (e.g., a steep slope or following There are several advantages in using pipeline systems the contour on a hillside). [Fiche 3.1: Off-farm Pipeline Conveyance]. They are char- acterized by high water-use efficiencies due to negligible Piped systems come in useful since seepage and operational losses. Pipe systems are also small ditches and canals are very more conducive to achieving more flexible water delivery, difficult to maintain properly, take up thereby placing more of the control of irrigation water sup- valuable land, and have high seepage losses (although the latter is beneficial ply in the hands of the farmer. to the environment). As a result, smaller pipelines, rather than small Piped systems may also facilitate adoption of advanced canals, are often used to supply groups of farmers and fields. on-farm irrigation technology (such as sprinklers and micro- Water can flow into a pipeline by gravity or be pumped in. Outlet irrigation), thereby enabling efficient application of water by water pressure can either be raised to supply advanced on-farm farmers in their fields, with little labor involved. However, it irrigation systems (e.g., sprinkler, drip) or can be low enough for the is also extremely common to supply micro (drip) irrigation water to flow directly to the fields from the outlet. directly from canals. THE ‘WHAT’ OF I&M IN I&D 41 I&M programs have typically been most Comparing Irrigation Modernization Approaches successful when they involved straightforward Modernization plans that aim to improve water delivery service features and simple operations. throughout the water supply network typically work well when they incorporate relatively straightforward features.46 Such modernization involves relatively simple changes and reduced operational labor input—although labor savings are often shifted toward improved maintenance. Typically, such modernization programs are not only simple, successful, and sustainable, but also more responsive to the farmers’ needs.47 Overall, simpler modernization plans have gener- ally proven more successful. Moving to schemes that use very advanced technology usually cre- ates higher levels of risk. More advanced schemes typically involve some level of automation to improve their operation (and minimize mistakes). These include automatic or semi-automatic systems.48 For example, any upstream control canal structure or pump can be automated, by fitting programmable logic controllers [Fiche 3.5: Automation with Programmable Logic Controllers (PLC)]. However, Moreover, automation of canal structures must be properly PLC automation is more vulnerable to technical problems and, to be selected or fit correctly into an overall distribution network successful, requires high levels of expertise, sustained budgets, and operation plan. If not, modernization programs can turn out available local technical specialists for long-term sustainability. to have no benefit or be only moderately successful and sustainable. The feasibility of applying the latest technology and ap- 46 These elements may include long-crested weirs, regulating reservoirs and proaches will depend on the starting point of the I&D schemes improved gates, along with appropriate training, as well as improved software for receiving water orders and scheduling flow changes throughout the project daily. in question. Depending on the existing level of development, a gradual approach to improvements with intermediary steps 47 They may, for example, allow for arranged delivery schedules. is advisable. Thus, any attempts at modernization and use of 48 Semi-automatic (or semi-fixed) systems combine fixed structures with adjustable innovative approaches should only be undertaken following ones. Hydraulically automated systems are equipped with either downstream or upstream control devices that control water levels in canals over a wide range of thorough assessments of local conditions, including resourc- discharge. es and capacities. 42 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Selection of appropriate modernization measures will also de- Applying Innovations across Different Schemes pend on the needs at hand, such as the types of crops to be and Delivery Schedules served, ease of maintenance and operation of schemes by staff, the cost of the technology, and environmental factors (such as Reliability, equity, and flexibility in water service requires con- the availability of necessary land and water resources). For these certed planning and investment in I&M. Many of the innovations reasons, a comprehensive modernization plan is required. mentioned above (and described in the technical fiches) can form Moreover, introducing new technologies necessitates a higher part of modernization plans (discussed in Chapter 4) in numerous level of expertise and specialization for their use, maintenance, situations—whatever the system or delivery schedule in question. and repair (as compared to simpler, manually operated schemes Advances in technological innovations related to upgrading of that are more labor-intensive). With I&M, a reduction in the labor physical infrastructure for improving the performance of irrigation force serving the I&D schemes is commonly observed. However, schemes encompass a variety of approaches, from low to high- the staff hired to manage, operate, and maintain modernized tech. Even a poorly operating system can be converted into a schemes are also paid at higher salary scales, thereby indicating more efficient and more responsive network. Included in such a financial trade-off [Fiche 3.7: Staffing]. approaches is automation of some key structures. All of these must be supported by appropriate levels of management, opera- The operation and tion, and maintenance (MOM). maintenance of new technologies requires a In many I&D schemes, modernization has been successfully im- higher level of expertise plemented through gradual achievement of clear water service and specialization. goals. These interventions typically focus on simple objectives such as (i) good upstream water level control; (ii) improved flow measurement and control; (iii) strategically placed regulating reservoirs; (iv) improved communications and remote monitor- ing; and (v) conversion of small canals to pipelines (pumped or gravity). Other common steps include: (i) control of conveyance water losses (via lining or choice of construction material for canals); (ii) balancing of water storage; (iii) energy efficiency; and (iv) im- proved on-farm water application efficiency (including use of land levelling, soil moisture management, etc.). THE ‘WHAT’ OF I&M IN I&D 43 Supervisory Control and Data Acquisition (SCADA) An innovation that can be applied across the board and has proven to be one of the most valuable moderniza- tion tools available is the Supervisory Control and Data Acquisition (SCADA) system, also referred to as telemetry [Fiche 3.6: SCADA]. A SCADA system supports the ad- vanced automation of irrigation canals and is an example of remote control.51 The term ‘SCADA’ encompasses numerous technologies and possibilities—ranging from very simple occasional remote monitoring of key values (such as water levels or flow rates) to the communication and support system of very complex automation controls. The experience of Successful I&M interventions Punjab in Pakistan demonstrates the value of employing typically focus on simple a specialist cadre of SCADA technicians, as well as some objectives such as water of the challenges faced even after more than a decade level and flow control, and of experience with the systems. regulating reservoirs. The abovementioned types of I&M can enable the achievement of flex- 49 The approach has been very successful in the western USA and ible arranged water delivery schedules and use of pressurized on-farm Spain (with more than four million hectares modernized in the last 20 years), where it is now common in many irrigation projects for farmers irrigation systems (even those supplied from canals).49 to have very flexible arranged water delivery schedules. Remote Control 50 Automation of a remote-control process can, for example, be done by having a sensor linked to an electronic controller that activates a Remote control technology enables a relay of system observations to gate when the canal water surface reaches a certain level. a central control point, from which adjustments can be remotely imple- 51 SCADA refers to a broad spectrum of electronic hardware, com- mented. Users of remote control technology are able to perform actions puter software, and communications infrastructure that provides a platform for remote monitoring and control. SCADA systems can more efficiently and observe several canal conditions at once.50 While provide (i) real-time monitoring; (ii) remote supervisory or automatic remote control is not necessary for all types of automation, it is commonly control; (iii) alert or emergency notifications; (iv) troubleshooting; and used for such purposes. (v) automatic data reporting and archiving capabilities. 44 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Modernizing Off-farm Drainage Drainage Water Reuse Approximately 30-80 percent of irrigation water provided to fields may Additionally, numerous solutions exist such as recovery and be consumed during its initial application. This is largely dependent recirculation of drainage water (either on- or off-farm). Since upon the on-farm irrigation efficiency. Drainage water—or that which drainage water reuse can create risks at system level, it was not consumed—must therefore be disposed of or be naturally has specific technical and management requirements (e.g., used to recharge the aquifer underlying fields.52 monitoring and management of soil quality, farmer aware- ness and training, and specific water entitlements). Off-farm drainage typically consists of open ditches and drainpipes. A range of benefits can be obtained from updating drainage infrastruc- At the basin scale, drainage water reuse requires a clear ture at system level. Modern off-farm drainage systems are designed governance framework and an integrated water resources to address current agricultural realities. They allow for better yields management approach because of multiple impacts on nat- and more resilient production systems. ural resource systems. Because of the trade-offs involved, drainage water reuse planning and management require participatory approaches along with a multistakeholder governance and management structure. Flood Control Drainage also allows for effective control of flood risk by har- vesting flood waters for beneficial uses such as irrigation. For example, a method of flood management is presented by use of water spreading weirs. They represent a technical innovation (for adaptive management of land restoration) to regulate seasonal floodwaters, reduce runoff, and minimize erosion. Such structural interventions provide alternative pathways for flood water and slow its progress. 52 In modernized irrigation schemes the emphasis tends to be on Modern off-farm drainage systems improved first-time irrigation water application efficiency so that there is typically consist of open ditches and less drainage water to deal with. In other words, the strategy is to have drainpipes. improved source control. THE ‘WHAT’ OF I&M IN I&D 45 III. Investing in On-farm I&M What Do Farmers Want and How Can I&M Help? As discussed in the preceding chapter (the ‘Why’), farmers primarily want to attain higher net returns from irrigated agriculture—and prefer- ably face fewer challenges in the process of irrigating and cultivating their crops. Farmers also require relevant tools to be able to adapt to various chang- es faced in their operating environments—including water scarcity, new regulations, changes in prices and profitability brought about by market movements or economic downturns, and so forth. They also desire to adapt to emerging opportunities such as the availability of new and higher-value markets, or of new and more profitable crop varieties. Modernized on-farm irrigation can help farmers achieve higher incomes and adapt to a changing environment by ensuring that the optimum amount of water (along with nutrients and oxygen) is delivered to the plant roots at the right time (particularly at critical growth stages). Such improved control over on-farm water applications can improve crop yields and quality, allowing for more flexibility in choice of crops and varieties and in scheduling the cropping season. It can also reduce risks from water stress and result in lower production costs, including by using less water or less labor. Modernized on-farm irrigation can also have benefits beyond the farm- er’s production objectives. It can reduce nonbeneficial water use that Modernized on-farm does not contribute to crop growth, thereby enabling potential release irrigation can improve crop yields and quality, and of water for other uses. In addition, it can also contribute to a more en- allows for greater choice of vironmentally sensitive agriculture through improved soil health, lower crops and varieties. pollution levels, and reduced groundwater depletion. 46 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The Approach to On-Farm Irrigation I&M Box 3.3 On-Farm Water Storage Whether it is within a system-level modernization program or on the ini- tiative of individual farmers or of farmer organizations such as WUAs, Farmers invest in on-farm storage mainly to improve several preconditions typically shape the planning, implementation, and their control over the water delivered to them. For operation of innovative solutions for irrigated farming [Fiche 3.8: On-Farm example, the main scheme may only deliver water once Irrigation Design and Standards, Knowledge, and Support Network]. a week or operate on a 24-hour basis, both of which may be incompatible with the needs of that farmer and The first condition is to be sure of the quality of water delivery service crop water requirements. that farmers will be receiving from their service provider or from the water With on-farm storage, a week’s worth of water may be resources they control (such as private wells or springs, or abstraction received fairly rapidly and then used gradually over a rights). If water is delivered reliably on a rotation schedule (or some other week, for example. Farmers may also pump from an arranged schedule) or on demand, then a range of different tools and on-farm reservoir and deliver pressurized water to their innovations may be applicable. fields, where needed. Additionally, in countries such as Thailand, India, and Sri Lanka, small reservoirs used as However, if there is a chance that water supplies will not arrive on time fishponds provide extra farm income. or in the quantity required by the crops, the risks of investing in more ef- ficient on-farm application technology increase. Nonetheless, there are solutions for addressing lack of water supply reliability, such as on-farm water storage [Fiche 3.9: On-farm Water Reservoirs] or supplementing surface water deliveries with groundwater. The second condition is for farmers to be sure that the I&M options se- lected fit within their operating environment and their skill level. To that end, the tools proposed for I&M need to be suited to the actual condi- tions encountered in the field—for example, local climatic, topographic, and soil conditions. The on-farm systems also need to be adapted to the intended crop- ping pattern. Farmers need to understand how demanding the on-farm irrigation system is—whether it requires sophisticated design, favorable physical conditions, and highly skilled management. If so, farmers must be able to ensure that such tools are available. THE ‘WHAT’ OF I&M IN I&D 47 Farmers also need to ensure that the chosen irrigation system’s be spread on-farm either by techniques of surface irrigation or features and risk profile are suited to their farming enterprise and by use of pressurized irrigation schemes. I&M has much to offer to the prevalent social and organizational context.53 In addition, in both cases. the farmer will need to know if sufficiently skilled labor is available locally to help them install and operate the new systems and asso- Surface irrigation is the application of water to the fields at ciated equipment. Energy expenditures also play a role in deciding ground level. Surface irrigation has several variations. Common on the appropriate on-farm systems. surface irrigation methods include furrow,55 border,56 basin,57 or flood. With surface irrigation, either the entire field is flooded, Finally, and perhaps most importantly, the scheme will need to be or water is directed into furrows or borders. affordable, with an acceptable cost-benefit ratio and economies of scale. For example, in some extremely large schemes, the Surface irrigation performance can be enhanced if water is avail- water delivery system may serve an extensive patchwork of tiny able from an irrigation system in a reliable and flexible manner. individual plots—which may greatly limit the scope for innovation.54 Possible ways to modernize surface irrigation are discussed Under such circumstances, the overriding priority may be to up- in the following section. Alternatively, in areas where water is grade the water delivery system rather than tackle field-level I&M. available in a timely and predictable fashion, farmers may opt Nonetheless, more reliable and flexible water service would still al- towards adopting pressurized on-farm irrigation systems. low farmers to improve their incomes by changing crop cultivation practices, potentially switching to higher-value crops or varieties, and increasing the efficiency in use of agricultural inputs other than 53 For an in-depth look at the way in which new technologies for smallhold- ers in sub-Saharan Africa are embedded in wider social and organizational water. relations and have both social requirements and effects, see the FLID Guide Chapter 7, Transformative Technologies and Their Social Implications. Flexibility in such instances can be achieved by various means, notably by investing in simultaneous use of surface water and 54 Most of the world’s irrigated area is in East and South Asia, often in very large schemes of 500,000 to 1,000,000+ ha, where tertiary channels are groundwater (conjunctive use), intermediate storage within the ca- few and far between, field channels—if any—are at least 25-50 m from the nal, regulating reservoirs, or terminal farm-level storage. offtake, and water moves from plot to plot. 55 Furrows are narrow ditches dug on the field between the rows of crops. The Essentials of On-Farm I&M 56 With border irrigation, the field is divided into strips (also called borders or border strips) by parallel dikes or border ridges. With a variety of methods for applying water to an irrigated field, 57 Basin irrigation is commonly used to grow crops on flat lands, or in the main on-farm water application methods can be classified as terraces or hillsides. Basins are horizontal flat plots of land surrounded by surface, sprinkler, and micro irrigation systems. These can be di- small dikes or bunds, where the banks prevent water from flowing into the vided into two basic ways of irrigating on-farm. Irrigation water can surrounding fields. 48 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Modernizing On-Farm Surface Irrigation Other procedures may be used to shape a field surface so that the new slope is variable (but always downhill and not too steep). The Major advantages for modernizing surface irrigation are the latter may more closely match the original topography and reduce low investment cost and simplicity [Fiche 3.10: Modernized the volume of earth moved. Other types of equipment do not change Surface Irrigation]. Modernized surface irrigation can convert slopes but rather smooth out localized soil surfaces, often referred traditional surface irrigation from simple water spreading into to as land planing [Fiche 3.11: Land Grading, Leveling, and Planing]. a well-controlled practice with reasonable uniformity of water application and infiltration across a field. Some options for im- The most advanced land grading employs laser equipment. proving use of surface irrigation are discussed below. Precision land leveling by laser-guided equipment, or laser land leveling (LLL), has been used since the 1970s and is more detailed Land Leveling (Grading) and reliable than visual judgment or land surveyance. It represents one of the most important modern technologies available to irrigat- Often the first and most valuable investment for surface irriga- ing farmers as a cost-effective method of field preparation. tion is land leveling (or grading). Land leveling is used as a way of creating flat fields in preparation for planting and eventual As a faster method of field leveling, laser leveling also saves on use of irrigation systems. It increases the uniformity by smooth- time and costs, requiring fewer labor hours to complete. Besides ing the soil and redistributing it throughout a field to create helping reduce water waste, land levelling helps eliminate fertilizer a ground surface that allows the consistent advance of water and chemical runoff, thereby protecting waterways. across a field [Fiche 3.11: Land Grading, Leveling, and Planing]. Improved Tillage and Furrow Formation Land leveling is commonly applied to mildly sloping land, with a process that grades the field to an even surface, thereby Under ideal conditions, farmers can have excellent crop yields eliminating high and low areas.58 It is typically accomplished and fairly high irrigation efficiencies if they use furrow irrigation. through mechanized grading of agricultural land (based on a For the best results, the furrows and seedbeds must be properly constructed. Good furrow construction and shaping facilitates uni- detailed engineering survey, design, and layout). form irrigation, with uniform water movement into the seedbeds, Various procedures can be used to that end. One may use and avoidance of dry or flooded areas—all of which are needed to specific software and equipment to create a uniform plane that obtain a uniform and healthy crop stand. provides a constant downslope and cross-slope across a field. The best equipment options will depend upon the crop (for ex- ample, whether the stalks are thick or weak), the soil type (clay versus sandy), soil depth (shallow versus deep), and the bed shape 58 Land grading requires equipment that can remove soil from high points while rapidly transporting such soil volumes to other areas of the field, and chosen. Recommended tillage operational steps are described in subsequently filling the lower areas. Attachment 3: Improved Tillage and Furrow Formation. THE ‘WHAT’ OF I&M IN I&D 49 Sprinkler Systems Sprinkler systems provide highly uniform With sprinkler irrigation, water flows across a field through a pipe application rates system under pressure by which artificial rainfall is created. The independent of soil type. spraying is accomplished by using mechanized or nonmechanized sprinklers. Water is typically applied through overhead high-pres- sure sprinklers from a central location in the field or from sprinklers on moving platforms. Typical benefits from sprinkler irrigation include the ability to irrigate land that is not very level with an application rate of high unifor- mity that is independent of soil type (in contrast to surface irrigation, where distribution uniformity is a function of the soil infiltration rate). Common sprinkler types include movable, fixed set, and pivot sprin- klers. Some of the sprinkler variations are discussed below. Linear Move and Center Pivot Sprinklers Carriage or Skid-mounted Sprinklers The two forms of sprinkler system commonly used on large fields are linear moves and center pivots [Fiche 3.12: Linear and Center Carriage or skid-mounted sprinkler systems are commonly Pivot Sprinklers]. used for small, mobile applications and are the most appro- priate for small farms and fields. There are three common These sprinkler systems work best on larger farms and large fields. configurations: (i) the soft hose single sprinkler traveler; (ii) the Linear move systems can achieve high uniformities of water applica- traveler with hard polyethylene hose; and (iii) the hard hose tion because of the continuous movement across a field, the close reeled sprinkler booms [Fiche 3.13: Travelers and Hose Reel sprinkler spacing with adequate overlap, and the use of pressure Sprinklers]. regulators on individual sprinklers. Hand Move Sprinklers Center pivots are typically the least expensive and easiest to man- age by a large farmer when basic conditions are met, such as: large, Hand move sprinklers are cheap but labor-intensive systems continuous fields; inexpensive land, so that the corners do not need used on small farms. They consist of a movable pipe with sprin- to be irrigated; soils with relatively high intake rates (such as sandy klers on top, which can be attached to a stationary supply. The loam or loamy sand soils); and crops that are well suited to sprinkler aim is a schedule that meets specific watering requirements irrigation, such as cotton, small grains, safflower, or alfalfa. while minimizing labor costs. 50 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Micro-irrigation is a type of localized irrigation where water is led to the field through a pipe system and a tube is installed next to a row of Micro-irrigation includes any localized irrigation method that slowly plants or trees, with drops of water delivered at or near the provides water directly to the plant root zone in small, frequent, local- root at regular intervals59 [Fiche 3.14: Drip/Micro Irrigation]. In ized water applications (at low pressures) that do not wet the entire this type of irrigation, evaporation and runoff are minimized. soil surface. In this way, optimum conditions for plant growth can be obtained with the minimum of water. However, with their unique equipment and components, these systems have specialized needs and problems, such Micro-irrigation has the potential for precise and extremely flexible as: (i) susceptibility of emitters and orifices to plugging;60 (ii) irrigation methods. It can be adapted to almost any cropping situation high maintenance costs and routine field checks; and (iii) high and climatic zone, installed as either a surface or subsurface water initial capital costs as well as water treatment and filtration application system. Micro-irrigation is most often used with high-value costs. specialty crops. The specific form of micro-irrigation used depends largely Micro irrigation includes micro-sprayers, micro-sprinklers, surface upon the crop, the soil, and the technological capability of drip, and subsurface drip. Of these, the most popular method is sur- the farmers. A properly designed, installed, and maintained face drip irrigation. Surface drip irrigation (also called trickle irrigation) microsystem will provide better uniformity of water distribu- tion throughout a field than any other irrigation system.61 If successful micro-irrigation and the necessary support infra- structure are not already well established locally, investment must focus on simplicity and just making a system function properly with good equipment and maintenance. 59 A hole is made in the tube for an emitter, though which water is supplied slowly, drop by drop, to the plants. 60 This commonly requires water supply filtration and treatment to remove sediment, bacteria, algae, and other debris. 61 In some areas of the world—for example, Israel and California—the industry has matured after more than 40 years of implementation. In Micro-irrigation can be adapted to these locations, almost all the acreage of some crops (such as almonds, almost any cropping situation and pistachios, citrus, wine grapes, peppers, processing tomatoes and even climatic zone. cotton) are now irrigated using some form of micro-irrigation. THE ‘WHAT’ OF I&M IN I&D 51 Success of on-farm micro irrigation systems can be attained amount (or percentage) of water in the soil, a water content sen- through design standards, certified designers, equipment, and sor, or a soil moisture sensor,62 is needed. Soil moisture sensors well-trained and educated farmers. High levels of performance are effective at measuring the percentage of water in all soil types also require a sufficient maintenance budget, qualified profes- and textures of soil. sionals who can undertake maintenance (e.g., for emitters and Soil moisture measuring devices are part of field instrumentation their cleaning), and access to a network of private irrigation that enables accurate estimation of crop water requirements. Soil equipment providers. In many areas of the world this combina- moisture sensors range from simple (portable) to advanced. In tion may not be available. more advanced contexts, soil-moisture sensors using telemetry Fertigation can transmit soil-moisture data wirelessly to a laptop, tablet, or mo- bile phone for improved evaluation and monitoring. Sensors can Fertigation is the application of fertilizers via the irrigation water also be made part of a wireless communication system that gives [Fiche 3.15: Fertigation]. It has been used for decades with all ir- inputs for algorithms to control and manage irrigation systems.63 rigation systems (surface, sprinkler, micro). It was typically used as a convenient means of occasionally applying nitrogen fertilizer. In Innovations Applicable to Both Surface and recent years, it has become more sophisticated, with new forms Pressurized Systems of fertilizers, complete fertilizer mixes, spoon-feeding of fertilizers, Some innovations can bring benefits to both surface irrigation and and improved chemical injection hardware. pressurized systems. On-farm reservoirs can ensure that water is available when the crops require it and not simply when it happens Fertigation can provide substantial benefits in terms of improved to be delivered to the farm. This provides greater water control crop yields, crop quality, and more efficient irrigation. However, and can also eliminate the need to irrigate at night. Farmers may the uniformity of fertilizer distribution throughout a field can only also pump from an on-farm reservoir and deliver water to their be as good as the distribution uniformity of the irrigation water. fields under pressure. Often, too, these small reservoirs provide Hence, the benefits of fertigation are dependent upon the quality important additional income from fish [Fiche 3.9: On-farm Water of the irrigation system design and management. Reservoirs]. Measuring Soil Moisture Information on soil moisture is critical for deciding on the exact 62 Most soil moisture sensors are designed to estimate soil volumetric water content based on the dielectric constant of the soil (or soil bulk permittivity), amount of water required by a crop (in specific climatic condi- whereby measurement of the dielectric constant gives a predictable estimation tions) as well as for effective design and management of irrigation of water content. systems and scheduling [Fiche 3.16: Soil and Plant Water Status 63 Also, automatic irrigation is based on soil moisture sensor measurements for and Irrigation Scheduling]. To measure the rise and fall of the optimizing irrigation scheduling. 52 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Innovative tools can evaluate soil and plant water conditions and can Agro-ecological assess plant stress as a guide to crop irrigation scheduling. These tools solutions can help maintain soil health are used to ensure that the optimum amount of water enters the soil while managing water and reaches the plant roots. Innovations can also improve control and in agriculture. command of on-farm water management, for example, by using modern telemetry systems to match irrigation water delivery to crop needs [Fiche 3.17: Telemetry with Focus on On-farm Systems]. There are dozens of variations of un-pressurized surface irrigation as well as pressurized schemes (such as micro and sprinklers). Various sup- port elements, such as on-farm drainage, various sensors, land leveling, on-farm reservoirs, and tillage implements, are also part of the on-farm irrigation modernization sphere. Improving Productivity through Water and Soil Management In addition to the importance of water inputs, long-term sustainability of agricultural systems requires ensuring that soils stay productive and re- silient. Further to infrastructural solutions presented by I&D, appropriate soil-water management practices can help make the most of the water applied to the fields by maintaining soil health to ensure sufficient avail- ability of water in the root zone of plants.64 Management activities that help build soil health encompass traditional farming practices (commonly known as conservation, regenerative, or climate-smart agriculture). However, technologically advanced and inno- vative methods are also available and are discussed below. 64 Crop water productivity is governed by the crop growth and production parameters. It represents an efficacy parameter of the crop production process, whereby water (as well as other inputs) is subject to a transformation process of crop or biomass production. THE ‘WHAT’ OF I&M IN I&D 53 Precision Agriculture Box 3.4 Modernization for Precision Agriculture: Precision agriculture (PA) represents the use of large data Sequencing Infrastructure and Institutional Change sources (together with advanced crop and environmen- tal analytical tools) to identify soil and crop variability for To make the switch to precision irrigation, a farmer, or group of farm- improving farming practices and optimizing agronomic ers, such as a water user association (WUA), may need a change in inputs. Also known as digital agriculture, PA allows grow- their water control and delivery scheduling. For example, changes ers to collect, visualize, and evaluate crop and soil health may entail switching from a rotational canal delivery method with large conditions at various stages of production through thermal discharges (e.g., 5 days on and 5 days off) to smaller, more frequent remote sensing (RS)65 that can serve as an early indicator discharges (e.g., 16 hours a day). to detect potential problems. This may require a sizable, off-farm investment in the main canal deliv- ery system, such as building intermediate storage either in the canal PA enables managing the use of water to optimize wa- itself or in the WUA terminal water tanks, in order to preclude canal ter productivity and reduce the need for draining excess tail-end water losses. Thus, significant main-system investment may be water.66 It leads to an improved matching of crop water re- needed before investing in farm-level precision irrigation and its related quirements with irrigation water deliveries. Overall, it helps agricultural value chain. farmers adopt optimal management practices with the goal And when it comes to developing and empowering farmer institutions, of achieving both economic and environmental benefits. it makes more sense for advisory organizations to start engaging at the farm level with local water user groups (before moving on to WUAs). On-farm changes related to PA must be matched with an Starting at the grassroots level off-farm irrigation delivery that is very reliable and flexible. represents a more viable way This may require sizable off-farm investments as well as to engage local, farm-level associated institutional changes (Box 3.4). water users to participate in the selection of the moderniza- tion–investment mix, the O&M 65 Thermal RS estimates surface temperature, which serves as a rapid arrangements, and the cost- response variable that can indicate crop stresses prior to their visual sharing structure of the I&M symptoms. In contrast, optical RS utilizes visible light and infrared system. regions of the electromagnetic spectrum for crop and soil monitoring. It is, however, slow in differentiating stress levels in crops until visual Farmer participation will help keep the process from becoming a top- symptoms become noticeable. down negotiation between well-resourced system operators and the Precision irrigation can also reduce energy use and nitrous oxide 66 government, with the end users left out of the conversation. emissions that result from overwatering. 54 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Information and communications technology (ICT) Box 3.5 Using ICT for Precision Agriculture in Vietnam tools can aid precision agriculture for very ad- vanced farmers (Box 3.5). For example, ICT tools Precision agriculture includes the use of water ICT tools to sense meteorologi- can track meteorological temporal variability to in- cal temporal variability, inform farmers on how to schedule irrigation intervals form farmers on how to schedule irrigation intervals and discharges, and hence optimize water productivity and reduce excess and water discharges in an optimal way for higher drainage that causes diffuse pollution. water productivity and reduced drainage. The NetIrrigate phone app is a good illustration of a precision agriculture tool. It allows farmers to manage their irrigation equipment from a smartphone or Because smallholders may lack digital skills or may tablet. In a pilot scheme in Vietnam, rice farmers applied leading-edge ICT that not be able to afford the equipment, collective ap- helped to reduce the use of paddy water by 13-20 percent. However, these plication of ICT tools could be undertaken through high-tech solutions are knowledge- and labor-intensive. In particular, they a WUA. require frequently updated data about the water level below the soil. Precision agriculture can be supported by the The Vietnam pilot (as part of the World Bank-financed Vietnam Sustainable adoption of both remote sensing and on- and off- Agriculture Transformation (VnSAT) Project) was part of an irrigation investment farm use of ICT. mix that included introducing the Alternate Wetting and Drying (AWD) method for rice cultivation, which contributes to significant water saving and reduction in greenhouse gas emissions (GHGs). For farmers to trust and switch to the On-Farm Drainage AWD method at the farm level, the off-farm irrigation water delivery needs to be highly reliable and flexible to perfectly match the precise quantities of water Drainage helps to prevent rainfall from standing on required. fields or to remove excess water that has already entered the crop root zone. Drains may be surface Low-income farmers and smallholders may lack the necessary skills to reap or subsurface. the benefits of such digital applications, or the income to invest in them (tensi- ometers, for instance, are quite expensive). However, modern ICT-supported n Surface drainage removes surplus water irrigation advisory services (IAS) can be provided to a water user association from the soil surface and reduces the amount (WUA) rather than to individual farmers, thereby facilitating the shared applica- of water that will move into or through the soil. tion (and shared costs) of these tools. The widespread adoption of water ICT in a nation’s agriculture sector can help n Subsurface drainage collects and eliminates create economies of scale that could alter the cost-benefit profile of many water from within the soil with the help of I&M technologies and enable the country’s farmers to take a substantial step ditches and drainpipes, and typically consists forward in modernizing their irrigation and agronomic practices. of small conduits, a submain, a main, and an outlet. Subsurface drainage is frequently THE ‘WHAT’ OF I&M IN I&D 55 required to prevent waterlogging and soil salinization, and usual- The typical purpose of tile drains is to increase the root zone ly involves equipping areas (with irrigation facilities) with piped67 depth by lowering a high water table and to ensure aeration subsurface drainage systems. of the root zone. By removing this high water, salt is also re- moved—creating a healthy crop root zone. Tile drains have Tile Drainage the added advantage that they cause no loss of cultivable Modern drainage also includes the use of strategically placed tiles to land, and maintenance requirements are limited.68 allow water to flow away from farm fields [Fiche 3.18: Tile Drainage]. Tile Controlled Drainage drainage is a form of subsurface drainage that removes water from the soil more than the amount that can be held by capillary action. Innovations in recent years have included controlled drain- age to slow the movement of water through the soil profile Tile drains are buried pipes installed on a constant slope at depths of and so reduce loss of moisture and nutrients. In such cases, 1-2 meters below the ground surface. Water from saturated surround- the elevation of the drainage outlet is set to manage the ing soil flows into the pipe through many perforations in the pipe wall. water table in the crop production area to its optimum The pipes convey this water to a collector drain. Pipes are typically level and to limit the leakage of nutrients into surface and constructed with relatively thin-walled corrugated polyethylene. groundwater bodies.69 Drainage helps Controlled drainage is commonly used in humid areas to to prevent rainfall manage soil water during dry periods. In arid zones, the from standing on technique is largely used to control the soil-water balance fields or to remove and salinity. Controlled drainage can increase yields by re- excess water from ducing both loss of water and nutrients and can improve the crop root zone. soil aeration and cut waterlogging. 67 Drainage pipes are typicalliy constructed by using corrugated high- density polyethylene (HDPE) and corrugated polyvinyl chloride (PVC). 68 However, with tile drainage, soil particles entering and clogging subsurface drains are a common problem. To mitigate, drain envelopes (made of porous material) are commonly placed around subsurface drains. 69 The control valve design for water table depth is straightforward and the valves can be easily installed by farmers. 56 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE CHAPTER FOUR The ‘How’ of I&M in I&D THE ‘HOW’ OF I&M IN I&D 57 Chapter Two—the ‘Why’—provided a strong ratio- By detailing how to modernize and innovate, this chapter describes what nale for engaging in innovation and modernization. separates great examples of I&M from poor attempts that end in failure. The Chapter Three—the ‘What’—presented a wide range main lessons are: of practical solutions that can be adapted and ap- plied in each irrigation or drainage context. However, 1. Make haste slowly, learn from mistakes, and beware of “miracle the record on I&M is mixed at best. solutions.” 2. Great results do not always require sophisticated interventions—much Many investments involved rehabilitation only. For can be obtained through relatively simple measures. example, a significant amount of funds spent on ca- nal lining to reduce leakage has yielded only meager 3. Be clear on the objectives, and identify an affordable level of modern- returns. There is also a track record of modernization ization that is sufficient to provide the required service level and can be failures, and of not of learning from those failures. So reliably managed by scheme operators and farmers. the question remains: Just how does one make I&M 4. Adopt a systems approach by taking a holistic perspective and recogniz- work? ing the interconnectedness of the components of an irrigation scheme. Section I of the chapter discusses the need at the system level for a partici- patory, iterative, and knowledge-based “process” approach to I&M planning and implementation. The section sets out the specifics of this process ap- proach—the steps involved in translating principles of service delivery into actionable plans. It provides guidance on how to conduct a diagnostic analy- sis of system performance, on how to innovate, and on how to formulate planning and design considerations. The discussion ends with tips on select- ing I&M options and on preparing I&M action plans. Section II describes how to plan and implement I&M at the level of the farmer, including advised criteria for selecting among multiple options. The section highlights the key preconditions: knowledge, careful planning, communica- tions and contractual arrangements, support networks and facilities, and access to finance. There is a track record of modernization failures, Section III discusses how governments can establish a support and incentive and of not learning from framework for I&M, and how a national irrigation strategy could drive this those failures. process. 58 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE I. I&M Planning at the System Level I&M is much more than the successful introduction of specific interventions or technologies. It is first and foremost a mindset. It represents a problem-solv- ing approach as well as a protocol of testing, monitoring, and learning (from both successes and failures) that must be internalized and institutionalized in every context that seeks to keep abreast of change. I&M is therefore also a Planners must have a way of adapting and responding to changing circumstances—such as evolv- clear understanding ing societal and water user needs—as well as shifting technology paradigms. of the options that can be used to All I&D schemes were originally designed to meet certain basic service deliv- provide the service ery objectives. However, those goalposts do not stay stationary—they move. that farmers need. For example, Pakistan’s Indus Basin Irrigation System, the world largest con- tiguous irrigation scheme, was designed by the British in the mid-nineteenth and incorporate the right new technologies; (iii) adapt century to spread water uniformly over as vast an area as possible using or create financing instruments that enable farmers proportional distribution guidelines. The basic objective then was relatively not only to upgrade their on-farm systems, but to ac- straightforward: achieving food security and avoiding famine. cess improved I&D services; (iv) reorient administrative Undoubtedly, a comprehensive, modernized water service that meets the institutions to manage, channel, and distribute national needs of today’s farmers will be more expensive to design, install, manage, and provincial resources; and (v) induce policy makers and maintain. Simultaneously with conducting a diagnosis or appraisal of to operate in the new context with an innovation-driv- existing I&D schemes, the I&M process explores the various objectives that en mindset. should be met via targeted investments. This requires that planners have This process could well take years, as I&M principles a clear understanding of water delivery service, and of options that can be are progressively integrated into strategic plans, as- used to provide the service that farmers need. set management systems, monitoring and evaluation However, understanding the systems approach and the concept of water (M&E) frameworks, and budgets and staffing plans, delivery service can be challenging in some irrigation departments or agen- and as innovative technologies are gradually intro- cies. This applies particularly to those that are underfunded, are responsible duced, tested, then modified or scaled up as part of an for deteriorating systems, and with staff overwhelmed with day-to-day chal- iterative process. The potential length of its duration lenges who are only able to focus on simple interventions (e.g., canal lining). underscores the reasons all key actors involved must The multipronged challenge is how to (i) shift the perceptions of authorities adopt a process approach, rather than seeing it simply responsible for I&D, who may feel daunted by the initial cost outlay; (ii) select in the form of a very lengthy linear sequence. THE ‘HOW’ OF I&M IN I&D 59 The I&M mindset has an overarching objective, a systems orien- to achieve the long-term goal. As part of that systems orientation, tation, and a bottom-up experimental approach. The overarching there needs to be a bottom-up experimental approach—a de- objective is the long-term goal—a “dot on the horizon.” A systems liberate engineering and political learning process, starting with orientation is an understanding of how the different parts interlock on-the-ground realities. Overarching objective – horizon Modernized for performance h es ro ac p l ap u e ssf u cc gs a lin Sc n Interim goals d u ctio int r o ise Adjust goals, n, s tepw evolving I&M goals, l pla learning institutions nitia i led i Deta Revise, plan, scale, learn Modernization High initial uncertainty / piloting pathway Fixing the viewfinder – vision Time & Experience & Acceptance/Convergence * Time-scale could be one investment project, but ideally a longer-term incremental approach 60 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE The I&M process, if it is done well, will also likely be heu- Such work requires dedication and perseverance at both the technical ristic, iterative, and to some degree “messy”—necessitating and institutional levels. It consists of the painstaking alteration of the the retracing of steps, the application of mid-course correc- engineering code to suit the unique profile of local conditions, or of the tions, and the recalibration of tactical goals as new evidence regulatory framework to put the right incentives in place to drive I&M. or pilot program data come to light, and as implementers try, fail, learn, and adapt. At the policy and regulatory levels, it will take genuine commitment and painstaking persistence to drive I&M. Doing so will require a good And it need not be ambitious in scale or concept, at least understanding not only of the technical possibilities but of the political at the outset. It might involve, for example, the piloting of realities that may stand in the way of forward movement, along with a two or three different water distribution regimes in a branch willingness to try out new things and to learn from both good and bad canal in a large scheme, prior to full-scheme overhaul. Or it experiences. could be the deliberate and gradual introduction of telem- etry to test how well the scheme works before scaling up. In Indeed, all I&M, properly conceived, should be a learning experience, this sense, innovation is a deliberate learning process that with the lessons not only folded back into individual I&M process- not only tries out new technologies but tests what works es, but also disseminated as best practices to guide similar future best in the social, institutional, political, and environmental interventions. context. Developing and Implementing Modernization Plans In practice, I&M needs to make space for two seemingly divergent approaches: (i) a systematic, objective-setting A modernization plan combines the knowledge and information from process that keeps the viewfinder firmly fixed on the goals scheme diagnostics and setting of objectives with pragmatic solutions that need to be reached (the horizon); and (ii) a “sandbox” and an understanding of how a whole irrigation system can function that creates space for learning, experimentation, and adap- properly. The plan provides specific hardware and operation plans for tive management as the I&M process proceeds. individual structures throughout an off-farm irrigation network, so that the network can be operated dynamically to deliver the intended qual- These two complementary approaches need to be built into ity of water delivery service. the entire innovation and modernization process—not only into the design of investment programs, or the writing of One key task of a modernization plan is to clarify the future approaches consultant terms of reference, but into the very mindset of for how water should be delivered to various hydraulic levels (primary, decision makers, scheme managers, and farmers. The two secondary, tertiary) throughout the scheme. Development of a mod- approaches should work in tandem to unlock creative, in- ernization plan before investment includes an excellent assessment of vestigative energies at all levels and offer incentives to go existing hardware, budgets, constraints, hydraulic features, education, beyond “business as usual.” and so on. THE ‘HOW’ OF I&M IN I&D 61 A modernization plan is thus needed to identify appropriate The typical five-year implementation period of a typical irrigation control strategies that define (i) how water should be moved investment project is a comparatively brief episode in the life of a throughout a project; (ii) where the flow rate needs to be con- good I&M program. Projects should be designed within a program- verted from a variable and somewhat uncontrolled flow back matic, learning framework that allows for piloting, correcting, and to a constant flow rate; (iii) what the rules will be for ordering scaling up. This means that part of the I&M process may be imple- water; (iv) who will operate various structures; and so on. mented under, say, a five-year project as the first phase of a longer programmatic and learning approach. In practice, this means more An Iterative Process performance-based lending, more multiphase approaches, and results frameworks that help track both physical outputs and those I&M is thus a gradual, iterative process, with both piloting and institutional in nature [Attachment 6: Factoring Modernization into learning integral to the plan. Even when the objective and the Investment Projects]. proposed I&M pathway are clear, small steps may be the best way to start in order to allow space to learn, make mistakes, and improve. For example, computerized, networked SCADA The Importance of Well-Designed (supervisory control and data acquisition) systems are be- Participatory Processes ing implemented step by step in Vietnam and Pakistan.70 The slow introduction of laser land leveling in Pakistan is another A Broad Participatory Process good example [Country Case Study 2: Adoption of Laser Land The decision-making process to select an irrigation regime needs Leveling in Punjab, Pakistan]. to incorporate the perspectives of policy makers, water resource Iterative planning means that the stakeholders continually managers, irrigation scheme managers, actual operators such as monitor the results and reformulate their planning, scaling up or ditch riders, and above all, farmers at each stage of the planning retrenching as need be. As each successive step is taken, the process—and at each iteration of those stages. The higher-level objectives may need some adjustment. For example, after initial stakeholders will need training in how to conduct an iterative I&M consultations on the problems likely to be faced in a project, process in partnership with other stakeholders and a shift in their an in-depth diagnostic analysis (see the discussion below on mindset towards a service orientation. Conducting a Diagnostic Analysis of System Performance) may Fortunately, these stakeholders—government, irrigation agen- reveal limits that will require the objectives to be somewhat cies—tend to be familiar with planning. They are also uniquely scaled back. positioned to conduct assessments to determine the viability of irrigation schemes—their value added to the sector and wider 70 See Chapter Three and Fiche 3.6: Supervisory Control and Data Acquisition economy, their environmental sustainability, and their role in creat- System (SCADA). ing rural incomes. 62 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE At the level of government and their agencies, open communication The Paramount Need to Involve Farmers and interaction among the different stakeholders is essential. Decision makers in government do not hold a single monolithic viewpoint (or It is essential that the participatory process be primarily driven unitary interest) but rather represent a set of different, sometimes con- by—and directed toward—the needs and objectives of the ir- flicting interests, knowledge systems, and approaches. Agencies for rigators. A participatory approach to I&M planning comprises water resources, irrigation, agriculture, and environment, as well as three phases that constitute a joint learning process: prob- for trade, planning, and finance, all have different information, policies, lem identification, conceptual design, and construction and and perspectives, as do industry representative bodies, chambers of re-design. The engagement of farmers typically strengthens commerce, and so on. all three phases, and leads to better—and more strongly “owned” and sustainable—solutions than more technocratic For instance, economists, who typically think in terms of incentives, approaches. agricultural productivity, output, and trade, may want to modern- ize to improve economic outcomes. Engineers may zero in on the It is therefore vital, in participatory approaches, to uphold technical possibilities, structural impossibilities, and feasibility issues. principles of inclusion and equity. The public interest of all Environmentalists see externalities. Although all these streams of irrigators collectively differs from the private interest of one knowledge are needed, a common problem is that only irrigation individual irrigator. It is important, too, to retain the principle engineering perspectives are heard, leaving other important consid- of broader public interest because there may be conflicts erations about outcomes out of the conversation. A comprehensive and tradeoffs with the farmers’ interests—such as fiscal con- consultation process will therefore be essential, as will concessions siderations and environmental boundaries, for instance. and tradeoffs among them. It should be borne in mind that, at this level, decisions may be made not to modernize—or even to decommission an aging irrigation scheme altogether if the cost of modernizing it is too high and the value-added of irrigated agriculture too low. Not all irrigation schemes necessarily need to be modernized as some would prove economically unviable. For example, many lift irrigation schemes in the Balkans have been decommissioned for economic reasons, primarily because of the cost of pumping water at altitude. These decisions require comprehensive and exhaustive assessments from multiple viewpoints, including eco- The engagement of farmers nomic, social, environmental, and hydrological perspectives, together leads to better, more strongly with wide consultation within government and with farmers. “owned” solutions. THE ‘HOW’ OF I&M IN I&D 63 One core starting point is understanding current irrigation prac- tices and problems, and the desires and long-term aspirations of the farmers. A participatory process is needed to engage opera- tors and water users in a dialogue about current constraints (for example, insecure water rights or the unreliability of water deliv- eries) and current opportunities (how a farm could become more profitable if its water service were more reliable, for example). The essence here is to outline new rules for water service, then discuss the implications in terms of technical solutions and costs. The participatory approach is also essential to ensure that incen- tives among all stakeholders are rational, balanced, well targeted, and aligned with stated objectives, and that they meet the re- quirements of farmers. Finally, facilitated discussions (perhaps The modernization plan needs to employing models, and decision games) would be very helpful satisfy the objectives of each group to translate the alternative engineering options—their benefits, of stakeholders—policy makers, costs, quality, and operating requirements—from maps and draw- scheme managers, and farmers. ings into easy-to-understand, real-world choices upon which decisions about service outcomes can be made. process that aims at providing excellent water delivery service to Incentives for All Stakeholders farmers in a transparent and efficient manner implicitly empow- ers the farmers as clients, thereby shifting enormous power from Incentives need to be aligned to support the desired changes irrigation service providers to farmers and farmer organizations. at all levels, especially at the level of scheme management and Reciprocally, service providers have to adjust to a service deliv- that of the farmers. In brief, as discussed in the “Why” chapter, ery mentality and practice. the modernization plan needs to satisfy the objectives of each This may be a paradigm change. In a sense, it requires the “mod- group of stakeholders—policy makers, scheme managers, and ernization of staff” along with the technology. Personnel will farmers. Inevitably there will be tradeoffs, but the end result must need to actively support the paradigm change, especially at the be a compromise accepted by all stakeholders. Otherwise, it will field level. Without such service mentality, modernization may be not work. doomed to fail. What is needed alongside this client orientation Obtaining support for the changes may prove particularly chal- is a mind open to constantly trying new things, to learning and lenging with scheme managers. An irrigation modernization improving. 64 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Innovation is a problem-driven, Knowledge, Innovation, and Capacity: I&M iterative, learning process. as a Knowledge-Based Approach Knowledge and Innovation The modernization planning process needs to be knowl- edge-based, with analyses and solutions that are supported by high-quality data. Use of evidence-based data at the outset is the foundation for improved information and moni- toring systems, a key component of modernization. Innovation is a problem-driven, iterative, learning process given potential resistance towards proposed interventions. For instance, in several countries, the introduction of long- crested weirs—a structure for controlling irrigation water level—met with strong initial resistance [Fiche 4.1: Controlling Upstream Canal Water Levels with Long-Crested Weirs]. adaptation with systematic planning and allow both, through use of innovation-oriented pilots. Iterative adaptation can be built into the Rather than urging a wholesale overhaul strategy, several process by consciously including a range of early learning pilots World Bank-financed operations—both off-farm and on-farm— into the design of the monitoring program, once the likely menu of have chosen to take an incremental, pilot-based approach to technical interventions has been determined. Where that is not pos- the introduction of such technologies. This gradual approach sible, system models, serious games, and field visits can generate the includes the tactical placing of pilots in areas where the im- change-space, although they do not replace first-hand learning and pact is most directly felt, and the use of a joint process of experience. learning and reflection that involves walk-throughs, farmer field schools, demonstration days, and impact evaluation. Staffing and Capacity Building Intentional learning pilots such as this have then led to broad Trained and motivated stakeholders are essential to I&M. This is the acceptance followed by rapid scale-up. Pilots can also be an case both at the level of scheme planners, managers, and operators, opportunity for the implementing agency to learn, refine, and and at the level of farmers. Arriving at an outcome in which the optimal set new goals. modernization plan is adopted and incentives for all stakeholders are The implication for project design is not to do away with in- aligned requires stakeholders with competent skills in participatory formed planning processes, but rather to integrate iterative and iterative planning. THE ‘HOW’ OF I&M IN I&D 65 Staff capacity that includes a good understanding of the system Empowered Clients and Qualified Consultants and process of I&M is the first step in any modernization program. Conversely, without staff capacity and a continuous learning It is the role of irrigation agencies—and their financial backers—to program—and without farmers understanding and adopting the ensure that consultants bring the right mindset, qualifications, and objectives and functions of the I&M changes—modernization track record for the I&M process. Experience has shown that, like will likely stall. Without training and awareness, operators could old generals fighting the previous war, consultants and consul- not work the new structures. tancy firms are too often prisoners of their own past insights. They frequently have settled ideas about what constitutes “moderniza- The success of modernization largely depends upon the avail- tion” and often end up imposing their views, rather than taking part ability of competent and empowered professionals. In this in the participatory, I&M learning process. instance, scheme managers will need to be supported by new operation protocols and a command infrastructure that allows The solution to this lies primarily on the demand side—with em- quick, effective decisions, plus excellent communications. powered clients. If those seeking to commission or finance I&M Mastering all this will require extensive capacity building. interventions have the mindset to insist upon the kind of I&M pro- cess set out above—and include this in requests for proposals and This is equally true at the implementation and the management, terms of reference—consultants and consultancy firms will likely operation, and maintenance (MOM) stages. Sustainable mod- respond by adapting. Solid qualifications and up-to-date experi- ernization requires a well-financed, stable cadre of motivated, ence are essential both for design and implementation. well-trained, pragmatic staff, and farmers with the incentive to view continual professional skills development. In the case of smaller schemes, it may be necessary to train local consultants in the required approaches, as has often been done in Needs are different for different constituencies—planners, en- small-scale irrigation projects and community-driven development gineers, or operators, respectively. Planners must understand projects, where efforts are made towards irrigation improvement. the benefits and challenges of modernization. Engineers must understand the details of design and operation. Operators must Centers of Knowledge and Partnerships clearly understand how to operate new structures that may Knowledge partnerships are a key resource for accessing the seem completely foreign to them [Fiche 3.7: Staffing]. most up-to-date knowledge, research outputs, and experiences Other needed skills relate to acquiring the knowledge required to deliver I&M. Engaging with the right networks is essential to to improve water service to the intended levels, but also working capacity building, knowledge sharing, and financing opportuni- cross-functionally with the private sector and service providers ties—particularly regarding engagement of the private sector. on various aspects of innovation and incorporating learning and There are excellent sources of international and regional knowl- innovation into the culture. edge on I&M. 66 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Partnerships may be formed between irrigation schemes and such Defining Problems and Setting Objectives centers. Institutional strengthening can also be achieved through partnerships. Effective partnerships can be important in assessing System-level objectives are essentially complementary to irrigation subsectors where there is scope to draw country-specific farmer objectives. They typically include maintaining or knowledge from a range of partners. Another area where a knowl- achieving high-quality, reliable, efficient, and timely water edge partner can often source top-notch expertise from within its service to farmers. However, system-level objectives may in-country network is in providing direct operational guidance. also include higher-level goals, such as coping with water resource shortages or reducing negative externalities such Translating Service Delivery Principles as soil depletion or environmental pollution. This is, in part, into Plans because more developed economies tend to have more vo- cal and more environmentally conscious constituents. The previous section set out the framework factors for modernization planning at the system level—and adoption of an iterative, step- One irrigation district in California, through determined by-step, problem-driven, participatory, knowledge-based process commitment to I&M, successfully set for itself and met the approach. This section now describes the actual steps involved in three major long-term goals of (i) improved operability and the process of planning modernization. conservation of water; (ii) fulfillment of farmers’ demand for more flexible and reliable water deliveries; and (iii) increased drought resilience, reduced pollution, and enhanced ground- System-level objectives include maintaining or water sustainability [Country Case Study 1: Successful Planning achieving high-quality, and Implementation of Modernization in California, USA]. reliable, efficient, and timely water service to farmers. From a policy maker’s perspective, higher-level objectives, as discussed in the “Why” chapter, may include (i) achieving more efficient, productive, and profitable irrigated agriculture; (ii) strengthening water security; (iii) improving the efficiency of public investment and reducing fiscal outlays; and (iv) increas- ing the nation and farming sector’s resilience in the face of climate change by meeting climate change mitigation and ad- aptation goals and commitments, including those made under international agreements such as the Nationally Determined Contributions agreed at the Paris and Glasgow Conferences of the Parties (COPS 21 and COPS 26, respectively). THE ‘HOW’ OF I&M IN I&D 67 Conducting a Diagnostic Analysis of Scheme Performance As a prerequisite to planning, an initial diagnosis—a “rapid ap- praisal,” as it were—is essential to produce some initial idea of the current state of the scheme and to identify the potential con- straints to improved performance and their roots. The diagnosis may also gauge current performance against the original design, and against comparable schemes elsewhere. The result will be a problem statement, along with a measure of A diagnostic should how far, if at all, the scheme falls short of meeting farmers’ cur- take a whole-system rent and evolving needs. It may also offer a preliminary idea of approach, looking at what is possible: What are the areas that could be improved in the performance of the context? What objectives are possible? What might be the all the functions of the scheme. technical (and institutional) pathway for attaining these objec- tives? As the process of objective setting and planning unfolds, more in-depth diagnostics would begin to point out what are the needs of various stakeholders, but monitoring key performance feasible innovations that could meet I&M objectives, and what indicators (KPI) is regarded as foundational because it helps de- process of planning, piloting, and implementation would be the termine the problem to be solved.71 most appropriate. In fact, the discussion with stakeholders could start with the ques- Typically, a diagnostic would take a whole-system approach, look- tion: What do we need to measure? In many cases, it will become ing at the performance of all the functions of the scheme, not just apparent that what is currently measured is not appropriate or is that of the physical infrastructure. The diagnostic is essentially a grossly insufficient. A typical example is the Delivery Performance performance assessment of the physical infrastructure’s function- Ratio used in Pakistan: it measures the difference in unit flows be- ing and an evaluation of overall scheme performance against a tween watercourses during peak period, but its reliability is highly set of indicators that measure the adequacy, equity, and reliability compromised notably by the cancellation of water turns, which of the water service. Essentially, “If you can’t measure it, you can’t are usually not monitored. modernize it.” Key to the diagnostic process are measurement and monitoring— Monitoring of KPIs is helpful in determining investment priorities. This is 71 and these could form the basis of permanent monitoring. What described in Country Case Study 12: Setting the Bar on Modernization: Canal should be monitored will depend on the objectives set and the de Provence in France. 68 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE In addition, since I&M can occur in both scheme- and basin-wide continual performance monitoring is one of the most useful out- water flows, water accounting should form part of the planning growths of modernization. The next section will elaborate on the process (box 4.1). Starting with the diagnostic, an important step diagnostic process that underlies performance monitoring. in the process is to move from a simple diagnostic to setting Standard Approaches to the Diagnostic Process up a permanent performance-monitoring process. Permanent, —and Avoiding Ones Too Mechanistic Benchmarking enables apples-to-apples comparison with other irrigation schemes. In this way, best practices can be identified Box 4.1 The Application of Water Accounting and the limits of what is possible can be established, along with in I&M Planning interventions that could help close the performance gap between better and less well-performing schemes. Water accounting was originally used largely to determine the water balance, and in that way contributed to assessing system Current standardized performance appraisal tools include the performance. Nowadays it is a crucial planning tool, serving FAO’s MASSCOTE (Mapping System and Services for Canal basin-wide (system-wide) diagnostics. It includes the myriad Operation Techniques), a performance assessment toolkit and functions of remote sensing, modeling, and ICT tools that can be 11‑step methodology for analyzing and evaluating the perfor- applied to assess modernization impacts on water quantity and quality (through comparison of “before” and “after” data). mance of different parts of a canal irrigation scheme in order develop a modernization strategy. MASSCOTE modules have Water accounting should, thus, form part of an I&M feasibility also been developed that can be applied to pressurized and lift study. Since I&M affects the return flows (for environmental flows irrigation schemes. and groundwater recharge), water accounting is often needed to inform investment decisions. For example, if I&M aims to de- In recent years, engineering assessments like MASSCOTE, which liver more flexible water supplies to farms, this typically leads to measure the performance of inputs, have been complemented increased operational (tail-end) losses, unless the return water is by irrigation performance measurement frameworks that rely recoverable downstream at low cost through drainage reuse or on remote-sensing data and algorithms. These frameworks can pumping. serve as transparent, unbiased tools for monitoring outcomes That is why irrigation and drainage systems in the water-short of irrigation service delivery while focusing on spatial patterns or arid areas in Egypt, Uzbekistan and India (the Uttar Pradesh across scales (for example, plot, command, state, national). The warabandi allocation system) were initially designed for a preset tools are complementary and can be used together. rotational water delivery. Hence the crucial importance of un- dertaking a basin-wide (system-wide) water accounting exercise Using diagnostic tools judiciously is as much an art as it is a sci- before investing in modernizing the delivery approach. ence. It is important to avoid placing too much faith in the tools and employing too mechanistic an approach to scheme diagnosis THE ‘HOW’ OF I&M IN I&D 69 and the identification of solutions. Diagnostic tools are useful Formulating Planning and Design Considerations for pinpointing performance problems and their causes, but practical experience indicates that, used on their own, they are Finding the Appropriate Level of Modernization of less value as guidelines for identifying the solutions and in- The main challenge for every irrigation scheme is to identify the novations that could form part of a modernization plan. level of modernization that will provide the required service level The tools may, for example, help identify the weak points in and can be managed by the scheme operators. Planning may well a scheme—such as the structures that are the most sensitive be at different scales and have several objectives, and it must take to disturbance, and thus require more frequent control and account of the multiple, varying interests and objectives that exist adjustment or replacement by new infrastructure. However, at the level of the farmer, the scheme, the basin, and the wider the tools cannot reveal the pragmatic solutions one should public. adopt. Solutions are highly context-specific and require broad expertise. For example, a common and seemingly simple modernization ob- jective such as “efficient water use” can have different meanings at different levels. “On-farm irrigation efficiency” is not the same as “project irrigation efficiency,” nor the same as “basin efficiency.” The failure to take account of the differences, hear them out, and synthesize them into a coherent package of appropriately matched objectives has resulted in numerous misguided investments. Planning and design can either be limited to specific innovations or cover the entire scheme, but the effects need to be assessed on a whole-system basis. Innovations may be adopted to solve spe- cific problems or to take advantage of specific new approaches. Alternatively, a major modernization program may be adopted, such as converting the scheme from open canals to pressurized pipe delivery. Diagnostic tools may In large complex schemes, a long-term, integrated approach is typi- help identify performance cally indicated, with a comprehensive modernization plan covering problems and their causes, but cannot reveal the the entire cycle from source to drainage and recirculation, followed pragmatic solutions and by an action program spelling out the specific sequence of steps innovations to be adopted. and investments to be made. 70 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Operator/WUA certified Flexible arranged (eg. ISO 9001) with schedule network , Governance integrated management software (more dense often with pipes and intermediate automated system): O&M, reservoirs accounting, resources, personnel, etc. Gates motorized and Flexible arranged automatically schedule canals with telecommanded, often Operator/WUA with intermediate reservoirs piped network, and integrated management and short times to SCADA software: O&M, accounting, respond to user changes resources, personnel, etc. Canals with irrigation Self-balancing main gates Operator/WUA with arranged with users on with float and orifice technical sta to manage the basis of modules water, provide irrigator requirements and assistance, O&M and availability prepare small improvement projects Irrigation with rotation Most gates motorized and Operator/WUA with a limited schemes, macro manually telecommanded -measurements, but support technician for water not yet micro- Levels management and measurements maintenance of existing infrastructure Operator/WUA with no internal organization, poor collection Irrigation without rotation schemes, no macro and Gates manually operated, unlined canals (or lined only in critical sections) of irrigation modernization management, lack of micro-measurement qualified management personnel, etc. No control gates, unlined canals Technology THE ‘HOW’ OF I&M IN I&D 71 Planning needs to cover not only investments in infrastruc- Factoring in Financial Considerations ture and equipment, but also how the innovations are to be implemented, managed, operated, and maintained. In all The selection of infrastructure options needs to take account of the cases, there needs to be scope for testing, learning, and whole-life cost of the investment. Economic analysis must factor in the adjusting. realistic life expectancies of equipment. The analysis also has to evalu- ate quality and the management, operation, and maintenance (MOM) Alongside innovation in infrastructure and equipment, the characteristics, including ease of operation and maintenance, and the way in which modernization fits with farming practices lifetime costs of operation and maintenance. also needs to be planned. The ideal is that modernization matches the specific farmer demand and opportunities as The use of asset management planning (AMP) is essential. The value of discussed in Section II. AMP is twofold. Firstly, it highlights the whole cost of the investment— not only the upfront capital cost, but also its useful depreciation life and This may include, for example, opening of new markets the costs of MOM. For example, when canal lining is a priority, it must be for higher-value fruit and vegetable produce, which make borne in mind that geomembranes typically have a lower lifetime cost investment in innovations profitable. In many cases, how- than traditional hardlining techniques [Fiche 4.2: Canal Lining]. ever, accompanying measures may need to be planned in liaison with other agencies, such as research and exten- Asset management planning highlights sion support to the intensification of farming, or stimulation the whole cost of the investment, and of private investment in downstream agro-processing and sets out the MOM requirements for marketing. maintaining target levels of performance. One very important consideration is how to manage the problem of clear water entitlements. A water service can- not be properly improved if the water entitlements are not clear. Unless farmers know what level of water service is assured, how much it will cost, and how it is to be paid for, they likely will not invest in I&M. Ultimately, then, what is needed is an iterative process of dialogue and technical, social, and economic assessments to set water service targets and prices, and then translate these into an executable form of reference for the farmer, such as a legal title or service contract. 72 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE AMP also sets out the MOM requirements for maintaining target levels of performance. This approach improves the knowledge available at the time of the initial choice and spells out the cost and institutional requirements throughout the life of the asset, underwriting the sustainability of the investment, and avoiding an immiserating cycle of inadequate mainte- nance and periodic rehabilitation. Additionally, MOM allows for decision making on the asset replacement schedule to be made. Cost reductions can be a main criterion for selecting an in- novation. Innovations may not only improve water control and make it more efficient, but can also reduce costs, including the costs of maintenance. A good example is a modernization pro- gram in Mexico, where light equipment financed by the World Bank reduced the cost of maintaining the canals and drains of the schemes by 50 percent. A share of farmers’ increased income Farmers need to know the estimated MOM costs associated should be recovered with various options if they are to be empowered partners through service fees, in decision-making. Scheme modernization can be costly, to cover MOM costs and once investments are in place, sustainable MOM is es- and depreciation. sential throughout the life of the assets. All too often, MOM is underfunded. Issues of increased costs and cost recovery need to be discussed Under a modernization program, farmers will typically increase with the government as well, as an integral part of I&M planning. their farm net income, and a share of this needs to be recov- In practice, many countries with large irrigation areas, especially in ered through increased service fees. Over the long run, these Asia, charge little or nothing for water. This is often a vexed political fees can be expected to cover relevant MOM costs as well as issue—as well as a critical issue for financing MOM and asset re- depreciation. Setting out the likely MOM costs of each alter- placement. Discussions of the implications of increased costs and native, and discussing with farmers how these costs will be the need for increased cost recovery should therefore be part of paid for, is thus an important part of the participatory planning I&M planning, not only with farmers but also with government deci- process. sion makers. THE ‘HOW’ OF I&M IN I&D 73 Box 4.2 I&M Linkage with Irrigation Water Pricing Through Financial and Non-Financial Mechanisms Efforts to improve the supply side of irrigation provision are often ac- increases resulting in large income losses to farmers (Scheierling & companied by those to implement appropriate irrigation water pricing. Treguer, 2016). For example, studies on price elasticity of demand Appropriate water pricing policies are seen as a means of improving the on irrigation water (Scheierling et al, 2006) indicate that ISF usually sustainability of the I&D schemes (Pronti & Berbel, 2023).72 Water pricing needs to be raised drastically above the service-cost recovery level is typically set to ensure sufficient revenue streams to allow for delivery to influence water demand (with a reasonably high elasticity attained of required irrigation services and to induce a higher water use ef- more in the modern rather than the flood-based, irrigation systems). ficiency. Irrigation water price (or use cost) serves both as cost-recovery At farm level, low elasticity owes to farmers lack of informed choice. and demand management mechanisms in the irrigation sector. At basin level, price demand elasticity would drop further, since, in absence of conservation through ISF or through non-price instru- In water resources economics, price instruments are sought when ments, downstream farmers would reuse water losses of upstream policy makers are worried about (recouping) steep marginal costs of ones (i.e., there is a tradeoff between reuse and conservation). developing new supplies; whereas quotas (restrictions) are sought when they worry more about the socioeconomic damage from water scarcity Farmers are generally willing to pay the irrigation price if water as a demand-management tool. The common goal of irrigation service reliability and improved irrigation service delivery are ensured (Yasin fee (ISF) is to recover costs and attain financial autonomy on O&M, et al, 2022). However, an ad-hoc application of ISF (where quotas rather than incentivize conservation (as a non-financial instrument). through WUAs and high-tech investment solutions would suffice) can impoverish some farmers, bringing up equity concerns. Thus, A generally accepted correlation between low charges and low effi- increases in price to recover costs of I&M are to be considered ciency in surface irrigation have informed the narrative on water pricing. alongside socio-economic conditions of farmers to ensure equity of Based on this asserted causal link, raising prices is seen as an avenue water access. For example, Chris Perry showed in a paper that ISF in to generate more careful water use practices and efficiency gains. Egypt and Iran would unnecessarily reduce farmer income by 30%, However, there is an important economic aspect to raising the price of while there are better alternatives to manage demand. Also, high irrigation water delivery known as price elasticity of demand. It reflects prices would unnecessarily transfer the ‘scarcity rent’ (i.e., product of the relationship between changing of prices and water demand in price and quantity) from farmers to water supplier/government due to agricultural water use. farmers’ inability to pay. Generally, the price elasticity of demand for irrigation water is expected to be low, with higher prices potentially having little effect on actual water use. Irrigators’ water demand is considered highly inelastic, 72 Similar analogy is found in water pollution economics: effluent charges especially in the short term and at low prices. Since irrigation demand are sought to recover increased abatement costs, whereas effluent permits is price-inelastic, small reductions in irrigation require large price are applied to curb pollution damage. 74 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Preparing I&M Action Plans I&M does not have to involve conversion of open canals into pressurized pipes schemes, canal lining, automation, The I&M process needs to be interpreted through an implementable and and telemetry—excellent, high-return results can often be financed action program. That program will set out what infrastructure, achieved with simpler and less costly measures, particu- equipment, institutional development, and capacity building investments larly additional regulating structures such as weirs, gates, need to be made, with a sequenced timetable and financing plan. and regulating reservoirs. The sequence spells out how I&M can be introduced in a logical manner How to Identify, Rank, and Cost Interventions: A Holistic with the minimum disruption. Trials and pilot projects will likely come Approach first—and these can have an important demonstration effect. The action plan may include “adaptive implementation” with learning cycles, with All options should be considered in the light of their mea- evaluation points allowing for a change of course if necessary. surable benefit in improving scheme performance. The first step is to assess the costs and benefits of what is The main investments may be introduced in a gradual manner. Where currently being done. Upon this baseline, the costs and a complete overhaul or scheme switch is programmed, it must be care- benefits of change can be set. fully integrated with the irrigation season so that farmers minimize any temporary reduction in crop production. In this process, the paramount Sometimes the improvements can be simple yet yield a consideration is usually reliability. Improvements for flexibility and efficien- high return. Innovations related to infrastructure and equip- cy need to be introduced in a way that does not compromise reliability. ment, along with arrangements for MOM, are likely to form the central part of most—but not all—modernization pack- Where new cropping patterns are to be introduced, modernization ages. In some instances, significant system performance needs to interface with agricultural planning. Interface with other pro- improvements have been achieved through the adoption grams, such as energy73 and transport, also needs to be spelled out. of modern management approaches and targeted mainte- The program should also specify how to build in performance-based nance, with little need for new infrastructure or equipment approaches. [Country Case Study  3: Modernization with Little Infra­ Selecting I&M options structure or Equipment in Madhya Pradesh, India]. The main concepts, building blocks, and technologies of I&M are well All I&M can follow the step-by-step, “start small” approach. proven and well tested—the wheel does not have to be reinvented. Change within larger and more complex schemes, how- ever, needs to be conducted within an integrated, holistic framework—and this requires a special skill set. Particularly On the interface with energy, see the discussion in Country Case Study 6: Irrigation 73 in very large, complex schemes, a long-term, integrated Modernization in Brazil. approach is required. THE ‘HOW’ OF I&M IN I&D 75 After the initial stages of trial and error, scaling up may require multiple Fit-for-Purpose Procurement changes both off-farm and on-farm in order to achieve the targeted objective. A good example is the use of AWD/SRI techniques in rice- Procurement planning and implementation is a funda- producing countries to achieve three simultaneous goals: conserving mental part of the process of innovating and modernizing water, increasing yields, and reducing greenhouse gases. AWD irrigation and drainage schemes. However, there can be (Alternate Wetting and Drying) is an efficient method of rice cultivation difficult tradeoffs in procurement decisions. In an externally within the System of Rice Intensification (SRI) that employs controlled or financed project, centralized competitive bidding may be intermittent flooding of rice paddies, rather than continuous flooding. required, yet farmers may wish to specify the company and system they prefer to acquire. For example, in a Mexico However, in all cases—whether small, simple schemes or large, complex fertigation program financed by the World Bank, demand- ones—the spirit and protocol of step-by-step progress, rigorous moni- driven procurement of on-farm systems allowed farmers toring and measuring, continual learning, and iterative adjustment is to directly select the vending company they wanted for applicable and essential. I&M processes need to follow this procedural providing both the physical pressurized system—including plan of testing, learning, adjusting, and scaling up. In fact, all programs drip, pivot, front advance, and gate pipes—and for its de- should have, as a built-in intrinsic element, an approach to project plan- sign and installation. Some 20,000 systems were acquired ning and design that allows for such learning and adjustment over the in this way without compromise to fiduciary requirements. entire course of implementation. A key issue for consideration in the procurement plan (PP) I&M processes should follow and project procurement strategy for development (PPSD) a step-by-step approach is the risk management necessary to support the develop- of rigorous monitoring, ment objectives of the project and deliver the best ‘value continual learning, and for money’. Savings to the client will come only from good iterative adjustment. feasibility studies and designs. The highest savings to the client come from construction. Hence, it is very important to have the best feasibility assessment for realizing con- siderable savings in the construction process, proper value engineering, and design—so that structures can be con- structed properly and in a timely manner. This also means that the main benefits are likely to accrue early. Therefore, spending a bit more of the resources on the feasibility as- sessments and design pays off very much in the long run and best practice. 76 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Ideal sequence of studies (consulting Project Concept Board Appraisal Implementation services) and work construction Note Presentation supervision in an I&D project preparation and implementation  Analysis of alternatives  Feasibility Studies (FS)  Detailed Design (DD)  Bidding documents / ideally ready Requests for Proposals process  Pre-Feasibility Studies  Environmental and (RFP) (Pre-FS) Social Impact Assessment  Detailed costing and Management Plans  Procurement and Proper procurement packaging of key  Project Procurement (ESIA/ESMP) contract award of works elements of pre-feasibility (Pre-FS), Strategy for Development feasibility (FS), detailed design (DD), (PPSD) started  PPSD and  Supervision procurement support (PS), and construc- Procurement Plan (PP) consultancy service to be completed signed before works tion supervision (CS) is fundamental contract is signed for success in project implementation and I&M. For example, a pre-feasibility stage involves the analysis of alterna- Another important consideration is the choice of a contract type, such as Lump Sum tives. At this stage, it is critical to have a sense (LS) or Time Based (TB), as they may directly affect the quality of deliverables of the of the direction in which a project should go. consulting services provided. The table below lists the pros and cons for each type. Experience shows that these types of Pre-FS studies need highly experienced person- nel/consultants (>30 years) that can provide Lump sum Time-based such guidance with few days of work. The task teams are encouraged to seek support Appropriate if the nature of water works and funding for Pre-FS through government Appropriate for clearly defined design is not clearly defined. It is easier for funding, ongoing Bank-financed projects, and assignments and where parameters the consulting firms to present proposals and trust funds for this type of a short assignment. do not change (e.g., design of a variations (e.g., different heights of a dam) treatment plant of Xm3/day in in cases where it is not easy to quantify the A Quality-based Selection (QBS), a Consultant place Y). inputs, but it is easy to define the cost per day of the expert to be engaged. Qualification (CQS), or even direct contract- ing, as appropriate, can be the selection Pros: Easy to adjust to the site and associated method used. There are strategic decisions Pros: Easier contract management. social and environmental constraints. to be made for the project at this point, such as whether there is a way to introduce pres- Cons: Difficult for a Client to Cons: Entails more effort in contract surized irrigation systems (pipes), whether it is supervise since consulting firms are management (i.e., to monitor the choice of paid against deliverables. alternatives and time spent). better to rehabilitate, or to introduce modern- ization and innovation. THE ‘HOW’ OF I&M IN I&D 77 For FS, DD, PS, and CS, different combinations are possible based 4. At the Request for Proposals (RFP) stage, where the on the level of complexity of the project. For simple projects with Terms of Reference are included, it is fundamental to be a low level of complexity, the classical approach of FS-DD-PS clear on what is expected from the study (i.e., deliverables), in lump-sum and after CS on time based may be appropriate. the composition of the necessary team of key experts, As complexity increases—as related to the extent of the area to their qualification requirements, and the global number of be studied, the level of scrutiny of the studies (e.g., through a months of key experts. panel of experts), the various geotechnical conditions, and the 5. At the technical evaluation stage, it is important to prop- unforeseen circumstances on the ground—approaches to bring erly review the technical evaluation report, and, for key in a time-based contract and separating FS from the rest become large-value consulting services, technical proposals more fit for purpose. Attachment 8 [Procurement Strategy for should be requested and reviewed jointly by technical and Consulting Services for Irrigation and Drainage Projects] exam- procurement specialists. Here, a proper balance of team ines and explains four typical options to group various services composition, key experts’ experience, and time spent in into procurement contracts. the field is a key aspect that is often overlooked. For large Finally, the need for strong collaboration between Bank techni- infrastructure projects, multiple technical disciplines are of- cal and procurement specialists needs to be emphasized. Within ten involved (e.g., a geotechnical expert may be key for an the task team, procurement work relies on close collaboration earth dam but not so for a concrete dam) that may warrant between the technical and procurement specialists throughout proper review by multiple technical specialists of the task the entire project cycle. In particular, their support to each other team to help better understand what is needed and ensure is emphasized in the following stages: that the technical proposals are responsive to the RFP. 6. At the financial evaluation stage, the weight attributed to 1. At the preparation of the PPSD and PP, decisions need to each cost, as specified in the RFP, must be based on the be taken that consider not only lthe estimated cost of the complexity of the work and evaluation of risks. The weight assignment but also quality and risks of the outcome. for financial evaluation may vary from 10% for consulting 2. At the Expression of Interest (EOI) stage, it is critical to be services of complex works to 30% for those of simple clear on the scope and main requirements of the consult- works. ing services and the qualification criteria (e.g., experiences 7. Lastly, at the time of contract signature, the minutes of in irrigation systems ranging from 5 ha or 20,000 ha differ negotiations and final contract shall be carefully reviewed greatly). by both procurement and technical specialists in order to 3. At the shortlist stage, it is important to ensure that the se- ensure the high quality of innovation and modernization in lected option(s) can perform. large irrigation development projects. 78 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Cautionary Tales and the Need for an Honest Review of Results Not all modernization attempts are successful, of course, and the number of failed or less-than-successful invest- ments around the world bear witness to this. This merely underscores the need to adopt a careful, pragmatic, often progressive approach. The risk and reality of failure show the importance of maintaining realism and employing a sys- tematic, step-by-step approach in the context of an iterative monitoring, planning, and implementation process. The essential point is to learn from mistakes. The problem is not the experience of trying and failing as such. Rather, it lies in launching out wholesale on modernization with no By providing improved water awareness of the possibility of failing (hence no apprecia- services better adapted to tion of the role of piloting), little sense of the need to learn farmers’ needs, system-level from mistakes, no insight into the value of daring to fail, and I&M may offer them the guided less by risk aversion than by a short-sightedness opportunity to adopt new and that takes success for granted. [Country Case Study 4: An innovative on-farm systems. Example of Learning by Doing in Morocco]. In Vietnam, a hard look at successes and failures of the modernization program yielded fresh creative ideas on how to minimize II. I&M at the Farm Level future failures. This also led to the creation of an irrigation training center in Hanoi. The Framework Factors for I&M at the Farm Level Stock-taking—in the form of a frank and thorough moni- Although on-farm I&M is generally farmer-led, it often responds to toring and evaluation process—is essential, culminating system-level changes in irrigation water service. Where farmers control in a major review once full operationality and the flow of their own supply of irrigation water—for example, by drawing from a benefits are expected to be available. A full performance spring or well, or by individual withdrawal from a watercourse—they review involving all stakeholders and thorough in-field may innovate independently. However, when the farm is supplied with documentation should be carried out several years after water from a collective or public irrigation scheme, the interactions be- installation. Recommendations need to be based on proven tween the two systems make cooperation essential. How this comes past achievements, not on expected future success. together depends on what is happening in the water delivery system. THE ‘HOW’ OF I&M IN I&D 79 Where the water supply system remains as collective or common, the farm- The ideal is a conjunction of these two processes— ers may nonetheless be able to modernize their on-farm system and thereby the service provider agrees with the farmer on I&M make better use of the existing water service, profit from its advantages, or changes that bring improvements to the water service, work around its constraints. For example, farmers with a water service that and the farmer invests in complementary changes that is irregular or has long intervals may—either with fellow irrigators or alone— optimize water use on the farm. decide to construct on-farm storage and convert to pressurized irrigation Where farmers have access to their own source of within the farm. water, the decision process may be simpler—but still Alternatively, system-level I&M may improve water service by increasing needs to be within a workable framework for sustain- quantities of water supplied, improving reliability, adapting scheduling and, ability. Farmers may have a water source independent overall, providing a service that is better adapted to farmers’ requirements. of a large irrigation scheme—for example, a local spring This offers farmers the opportunity to adopt a new on-farm system, although or well, or a community-managed, small-scale irrigation they are not obliged to do so. Typically, where these improvements in water scheme. In several countries or regions, such as in the delivery result from a negotiated agreement between the farmers and the Arabian Peninsula, India, Morocco, or the United Sates, service provider, farmers will be ready to plan the relevant complementary many individuals or groups have access to groundwa- on-farm I&M, such as conversion to furrow irrigation, adoption of pressur- ter, and this has driven rapid and successful on-farm ized irrigation, and so on. irrigation modernization. However, groundwater devel- opment and use is all too often unregulated, resulting in rapid depletion. Farmers begin their decision-making process by setting an objective—essentially answering the “Why” ques- tion (Chapter Two). They weigh the potential benefits of innovative technology—such as improving their ir- rigated farming and tapping into new markets—against the availability of water and land under an existing irrigation regime or, if system-level improvements are coming, against what they can do with a better water service. Farmers with irregular water service may opt to construct This diagnostic process enables them to set realistic on-farm storage and convert objectives—typically, business objectives to increase to pressurized irrigation. farm income by growing a more profitable crop; 80 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE improving crop yields or quality; taking advantage of a spe- n Is the technology well adapted to the agricultural market? For cific time-bound opportunity, such as off-season production; example, is the market dominated by corporate agribusiness reduce costs; or simply increase the irrigated area or cropping and, if so, how can smallholder farmers access it? What are intensity.74 the market’s requirements in terms of quality, timing, and price of agricultural produce? How realistic those objectives are depends on many framework factors—economic, regulatory, support environment—which de- n What is the market for supplying irrigation technology, and termine whether a new technology will be feasible. Fundamental what sort of technical support is available, particularly for questions within the framework include the following: smallholders? This encompasses the irrigation equipment and technology, their after-sales service, research and extension In a diagnostic process, farmers services, appropriate digital technology, producer groups, weigh the potential benefits of and knowledge-exchange platforms. innovative irrigation technology against the availability of water n Does the legal and regulatory framework support the type and land resources. of modernization envisaged? For example, do the irrigation scheme bylaws and legal frameworks that govern access, water rights, and arrangements for conjunctive use fit with the technology proposed? Does the land tenure system facilitate investment in modernization? Do water resource and environ- mental protection regulations permit the type and extent of water use envisaged—for example, do the regulations prevent overdrafting of groundwater or the pollution of watercourses? One all too common factor that influences farmers’ decisions, how- ever, is a distorted incentive framework. Distorted incentives may be generated by water that is virtually free, or subsidies offered only on certain types of irrigation equipment, or prices guaranteed only 74 The decision-making process for smallholder modernization is described for selected crops. In these circumstances, farmers may well make from the perspective of development planners in the 2021 World Bank choices which are economically unsound or unsustainable. This Farmer-led Irrigation Development Guide: A What, Why and How-to for points to the need for governments to provide a supportive, non-dis- Intervention Design. The FLID Guide sets out seven factors to consider, torting incentive framework. After taking all these framework factors two of which—assessment of resource potential and evaluation of farmer benefits—present the rationale for FLID improvement. These two factors into account, the farmer can then embark on a decision-taking pro- correspond to the process of decision-making described in this paragraph. cess that will end with a decision to adopt and invest—or not. THE ‘HOW’ OF I&M IN I&D 81 Essential Conditions for Farmers to Plan, Implement, and Operate Innovations Whether within a system-level modernization program or on the initiative of individual farmers and farmer groups, there are essential conditions for farmers to plan, implement, and operate innovations. Confidence in the Water Supply: Building Trust between Service Providers and Farmers Continuous, dependable water supply is critical for any farm. Farmers therefore need sound communication with their service provider, and confidence in the service they will Where I&M is conducted as a receive. At the time that they invest in I&M improvements, partnership between service farmers must be sure of the optimal type of water service provider and farmer, a relationship for their farming operation that is both technically feasible of mutual trust often emerges. and financially affordable. Once the innovations have been implemented, the work is far from over. The farmer needs Planning to be able to negotiate the assured quality of service each irrigation season. Careful planning is another important requirement. Building on the findings of the selection process, the farmer will need to prepare a One important factor here is therefore the level of mutual costed plan. At this stage, most farmers would benefit from expert trust—the extent to which farmers can rely on their water ser- advice and support—on this, see Disseminating Knowledge On, and vice provider to deliver the agreed service, and the extent Expanding Engagement With, Farm-Level I&M below. to which the farmers in turn honor their obligations to under- take operation and maintenance, pay service fees and so The level and complexity of the planning stage will vary considerably on. Where I&M is conducted as a partnership between ser- depending on the production and irrigation scheme in question, as vice provider and farmer, a relationship of mutual trust often well as on the farmer’s own educational background and technical emerges. However, where I&M is conducted at the system expertise. In many cases, the planning process will be quite informal. level in a topdown manner, with little consultation with the However, there is a considerable difference between the needs and farmers, the opposite effect—distrust and mutual suspicion— capabilities of, say, a hill farmer in Vietnam and those of a farmer in a will likely result. North American irrigation district. 82 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Access to Support Networks and Facilities Access to Financing Farmers’ access to support networks and facilities—equip- The final requirement is access to finance—both for investment in ment suppliers, irrigation consultants, financial facilities, user I&M and the extra working capital that may be required for more associations, professional bodies, and so on—is essential. The advanced technologies and cropping patterns. This may be obtain- ideal is to have an extensive system of irrigation equipment able from banks or specialized credit institutions. For equipment, dealers and irrigation designers who can advise on irrigation credit facilities may be obtainable from suppliers, including through layouts, equipment and so on, and provide post-sales follow- leasing or hire purchase agreements. up and support for operations. Preferably, there would be a An example from Kenya links farmers to both equipment suppliers system of public interest oversight or certification of these and the companies that buy the farm’s produce, creating a manage- dealers and designers (often the same firm in both roles). able chain with smoothly connected backward and forward linkages. Contracts between farmers and service providers should es- Nonetheless, there may be a need for government to strengthen tablish performance standards with specific verifiable metrics farmers’ access to finance, because this has been a perpetually weak and include postinstallation verification, with provision for re- link for many smallholders—see Accompanying Measures below. medial action and penalties if standards are not met. In this respect, the quality and reliability of infrastructure and equip- In real life, farmers follow an iterative approach, although not neces- ment are critical. Poorly executed works and poorly functioning sarily a particularly formal one. They go over the available options investments can ruin a farmer’s modernization program. and apply a healthy dose of common sense essentially to answer the question: “What is the key problem I am trying to solve, and is this a reasonably good solution—or are there more relevant and/ or lower cost alternatives?” A problem-driven, iterative approach will cull the frivolous from the essential, examine all requirements and relevant factors, and settle on a sound business strategy for the farm, be it based on a spreadsheet or a handshake. Much innovation evolves step by step. A farmer may, for example, test out a new technology on one part of the farm before deciding Farmers need whether to scale it to the remainder of the farm. Innovative tech- access to support nology can be quite simple, at least at first—great results are often networks that can provide them obtained through simple measures. One challenge may be the exis- with essential tence of a “modernization project” that ostensibly proves itself to be irrigation advice. an off-the-shelf solution to all the farmer’s problems—accompanied THE ‘HOW’ OF I&M IN I&D 83 by, for example, an 80 percent government subsidy of the price. The available. However, the key question is: How do farmers ac- farmer will almost certainly take it, but it is unlikely to result in sustain- quire the knowledge they need? able improvement. The challenge is to (i) organize a training program best suited Choosing the Right Innovation to the local context; (ii) develop or improve training and sup- port centers; and then (iii) roll out empowerment and support The range of innovative technology is enormous. Innovative individu- programs. An expertly designed awareness and skills devel- al farmers, businesses, and research and development organizations opment program for farmers is often an essential complement have developed a wide range of on-farm irrigation technologies for to modernization and should ideally run for at least one year both piped and surface irrigation schemes, as illustrated in this guide. after the installation of the equipment. These match different budgets, crops, soil characteristics, labor avail- ability, water quality, availability of power, availability of technical Therefore, a key factor in on-farm I&M is the interface with support, and levels of acceptable risk. The range of variation can be the irrigation service provider, who can provide both knowl- significant, and the dilemma for the farmer is how to choose among edge about on-farm I&M and its relation to standards of the options. water service, and actual guidance on which on-farm I&M is the most appropriate [Attachment 5: Innovation in Client The first step is to assess which on-farm innovations will make the Communication and Engagement]. best use of the available water. Every new on-farm irrigation or drainage technology needs to be assessed afresh using numerous Farmer-to-farmer criteria—for example, how suitable it is for growing the desired crop learning is a and conditions encountered in that area (e.g., the local climatic, topo- potent channel graphic, and soil conditions) as well as the available irrigation service for information. regime, and water quantity and quality. Disseminating Knowledge On, and Expanding Engagement With, Farm-Level I&M Organizing and Disseminating Appropriate Knowledge for Farmers To choose and operate new technology successfully, farmers need relevant knowledge across many disciplines. And indeed, basic ir- rigation knowledge and related equipment standards are widely 84 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE In practice, equipment dealers and irrigation designers are also valu- able sources of knowledge. Farmer-to-farmer learning is another potent channel for information. Additionally, farmers also learn from extension officers, the internet, the media, and finance institutions and aggregators. Accompanying Measures: Government’s Role in Supporting Farmer-Led I&M75 The Enabling Framework for On-Farm I&M Governments have vital roles to play. They bear the responsibility for establishing the policy and legal tools that create a viable, supportive setting for on-farm I&M. However, they also have the responsibility to protect the public good. This includes setting the regulatory frame- Government support work for sustainable, efficient water management and adaptation to to smallholders climate change. should encourage simplicity in I&M. Much of this regulatory and policy framework may create incentives that promote on-farm I&M—for example, enforceable water alloca- facilitation of market development; support to slow movers; tions and quotas, water pricing, pollution controls and so forth. In and facilitation of access to finance. However, with public addition, regulating land tenure can incentivize farmers. Where plots support of any kind, certain rules must be observed. One is are small, for example, some land consolidation may be needed to that government intervention should encourage I&M. To that make the most of modernization through economies of scale. end, government should respect the step-by-step, cumula- Direct Government Support to Engage Smallholders in I&M tive, and iterative nature of I&M by helping farmers increase their knowledge and capacity. It should also encourage sim- Government has numerous tools for fostering on-farm I&M. Among plicity (rather than complexity), thereby empowering farmers these, the most significant are its support of the knowledge agenda; to respond nimbly to changing circumstances. Subsidies, if there are any, should be “smart,” targeting specific goals and aimed at motivating behavioral changes that give farmers 75 In addition to these considerations on government support to farmer-led I&M, there is a role for governments to help create a modernization dynamic at the space to innovate, rather than dictating to them as a central national and system level—see Section III below. authority. THE ‘HOW’ OF I&M IN I&D 85 III. Promoting I&M at the In addition to promoting the knowledge and learning agenda at both the irrigation scheme and farm levels, the govern- National Level ment can provide support at the national level through work with academia and applied research institutes, using re- Developing a Framework that Encourages I&M search grants and competitions. The government can also provide seed finance for innovation through, for example, The role of government in providing an overall enabling and incentiv- challenge funds or subsidies to innovation initiatives within izing framework for I&M at both the system and farm levels has been public or private projects. referred to earlier. In this section, we now discuss the specific, high- level support that government can give to developing a framework that A legal and policy framework that is conducive to innova- encourages I&M through policy, planning, and finance, and support for tion is needed. Well-crafted policies on technology and on knowledge and learning. trade can also make valuable contributions. Industrial policy can promote access to technology through measures that encourage the development of local manufacturing, and Government can promote I&M at the national that facilitate the operation of local distribution networks level through a conducive policy and legal framework, work with learning and research and service providers. Where innovative technology must institutions, and seed finance for innovation. be imported, import duties on key equipment could be eased. Public policies can support the adoption of modernization packages through approaches such as irrigation manage- ment transfer. For example, the government of Mexico has been a leader in irrigation management transfer to business-type user associations—farmer associations large enough to be able to recruit professional management and to be financially independent.76 The Mexican examples have typically required a large measure of rehabilitation, but this also stimulated the initiation of modernization, a process that has subsequently continued apace. 76 A condition of the transfer was that the infrastructure must be in good operating condition. 86 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE Box 4.3 Integrating I&M Objectives into a National I&D Strategy: An Example from Central Asia Irrigation sector strategies, policies, and regulatory frameworks are grouped into categories for applying appropriate measures for, and typically used to strengthen the institutional environment for improved degrees of, modernization. irrigation water resource management and service delivery, which Measures to improve the performance of I&D schemes and relevant includes modernization efforts. To that end, a report was recently plans for modernization will require a development of enabling prepared based on a World Bank initiative on irrigation modernization in policy and legislative environment, potentially through institutional Central Asia. reform. Accordingly, as pertaining to the national level interven- The initiative (study) has allowed the Bank and its partners to take tions, necessary actions proposed by the paper include (i) policy stock of the current challenges with regards to irrigation services in development and legislation to set the direction and framework for Central Asia and to identify potential policy, institutional, and techni- modernization; (ii) institutional reform to facilitate changes in the cal measures, as well as important knowledge gaps. In this report, culture and practices of organizations, among others. a transformation is envisaged for improving productivity and water Significant investment is required over many years in the I&D sector conservation gains through modernization – with a move to a service to resolve the issues identified in the report, with a wide range of delivery culture ready to respond to changing needs and farmers’ measures already outlined for modernization of the I&D sector in demands. Central Asia. To that end, it is critical that each country identifies its This new direction supposes that irrigation agencies will be transparent specific objectives for the sector and prepares a short-, medium- and accountable to farmers for performance of the water delivery sys- and long-term plan for their achievement. The institutional change tem. More efficient and reliable irrigation is expected to build resilience required with modernization can be difficult to achieve. Ideally, this is and enhance production, which in turn will increase farmers’ ability and accomplished through a bottom-up demand-driven approach rather willingness to pay for the service provided. Such plans for moderniza- that the historic top-down supply-driven methods. Shared vision and tion of the irrigation and drainage sector in Central Asia need to be strategy are developed in a collaborative and inclusive manner. set in a supportive framework of policy development and institutional The World Bank can play an important supporting role in facilitating reform. inclusion of I&M considerations in national irrigation strategies. It can Differences in the types of I&D scheme are found in each country assist in this process with advice, funding, and technical assistance, due to prevalent climate, topography, markets, among other fac- particularly by identifying key policy interventions and supporting tors. Correspondingly, each country will have a different approach to the sector dialogue in the various countries and at regional level. modernization of their I&D systems. In this context each country must Lastly, a sector modernization plan can form the basis for long-term prepare a National Irrigation Sector Modernization Plan and Strategy for funding by the Bank, potentially under its Multiphase Programmatic the rehabilitation, upgrading, and modernization of their I&D systems. Approach (MPA), with funds allocated in tranches over 10-15 years During the creation of a national plan, various scheme types can be and distributed against achievement of agreed milestones. THE ‘HOW’ OF I&M IN I&D 87 The Mexico experience shows that where irrigation schemes are Irrigation is, in large part, a purely private activity—and irrigated the responsibility of the farmers themselves, a sense of ownership farming is almost entirely private—and the broader private sec- leads them to take the initiative to think through their options for tor is well-qualified to drive I&M. The strategy should therefore I&M and fully review the scope for innovation. The Mexico case set out the respective roles of the public and private sectors, also reveals that farmer-led I&M can take many different forms. and the ways in which incentives for both would be aligned in pursuit of the higher-level outcomes targeted. In Israel, for Another model is public-private partnerships in their various forms. example, the public and private sectors worked together in a In Israel, the government has been offering a commitment of context of extreme water scarcity, and this created a power- guaranteed but limited water quotas as its counterpart to private ful I&M dynamic [Country Case Study 8: The Public and Private investment in innovation. At the scheme level, governments may Sectors Working Together in Israel]. lease out concessions to private operators against specific perfor- mance targets that require modernization. Yet I&M can also support a progression away from publicly man- aged and financed schemes, toward treating irrigation more on More generally, the way the sector is financed can encourage a business-like footing. In some countries, such as Turkey and innovation. Often, smart subsidies are targeted at outputs and Mexico, for example, governments have gradually withdrawn outcomes rather than at promoting specific innovations (inputs). from the irrigation sector and transferred schemes to farmer This approach can help relatively vulnerable groups to access management. In other countries, such as Peru and Brazil, there modernization options. Finally, national irrigation agencies can be has also always been strong private investment in irrigation, and reformed to open up to participatory and partnership approaches, with this behind it, I&M can increase profitability and underwrite and to become more “I&M friendly.” the expansion of irrigation toward its full potential. Even on In light of the sector’s current state and trends, I&M investment pro- smallholder farms, modernization can create levels of profitabil- grams would outline the changes in infrastructure and institutions ity that allow for full cost recovery [see Country Case Study 6: that would align the sector with the agreed objectives. Country Irrigation Modernization in Brazil, where I&M allowed irrigation Case Study 7: The National Irrigation Modernization Program in to be treated as a business]. Argentina illustrates one country’s national modernization pro- gram. Each country’s programs are different. Because it is essential to involve all stakeholders, an outcome-driv- en, national program of investment and institutional change should link investment in infrastructure and management with supportive policy, institutional, and governance measures. One cardinal ele- ment is to define how public and private sectors will cooperate. 88 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE CONCLUSION CONCLUSION 89 I&M typically unfolds in a The tools, techniques, and infrastructural building blocks of series of gradual steps, I&M in I&D have already been tested and proven in a wide guided by an outlook variety of climates, soil conditions, farming cultures, and open to experimentation, adjustment, retracing, economies. In many settings, the key term missing in the and modification. equation for raising the scale, productivity, and value added of irrigated agriculture is a mindset of innovation. Innovation is more than the introduction of new technologies. It requires a problem-solving, collaborative outlook charac- terized by openness to learning and testing, high levels of creativity and communication, openness to new possibili- ties, and little fear of making mistakes. More often than not, planning or implementing I&M unfolds in a series of gradual, context-appropriate, trial-and-error steps undertaken pains- takingly over a long period, guided by an outlook open to experimentation, adjustment, retracing, and modification. That kind of success typically requires a step-by-step, it- erative process approach in which the major stakeholder groups continually monitor results, reformulate plans, return to the drawing board, and scale up or retrench as need be. It also involves progressively integrating I&M principles into national-level strategic plans, asset management systems, monitoring and evaluation frameworks, and budgets and staffing plans. Drilling further down into this process, Chapters Two, Three, and Four of this Guide have looked at a different aspect of the challenge of innovating and modernizing irrigation and drainage from the perspectives of the three main stakehold- er groups—farmers, irrigation scheme managers, and policy makers. Understandably, each group tends to see things from their own viewpoint. 90 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE An important factor, therefore, is trust-building. Relationships The key is to start simple and of trust tend to emerge and strengthen in the context of dia- small, aiming just to achieve robust, sustainable control that logue-based partnerships among stakeholders, and tend to results in good water delivery break down where I&M attempts are undertaken in an inflex- service as a first step. ible, top-down manner, with little consultation with farmers. The illustrative examples cited in this report, together with the technical fiches and country case studies, underscore the fact that achieving larger harvests of staples and high-value crops is more than just a matter of farmers watering fields. It involves an entire ecosystem, any component of which could undermine the entire I&M agenda if its participation is suboptimal. Besides mutual trust, another vital ecosystem-level factor therefore is the design of proper support structures. In ad- dition to land, water, and capital, farmers also need access to user associations, equipment suppliers, irrigation design consultants, financial facilities, professional bodies, and other support networks and facilities if they are to obtain best-prac- tice advice on the selection of equipment, optimal irrigation layouts, post-sales follow-up, and operational support. The overall lesson that recurs throughout this report is clear: research thoroughly, start modestly, build gradually, review regularly, improve continuously, and experiment frequently. The key is to start simple and small, aiming just to achieve robust, sustainable control that results in good water deliv- ery service as a first step. In summary, the solutions are out there—many of them superb, well-tested, appropriate, and relatively affordable. CONCLUSION 91 GLOSSARY OF TERMS 92 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE automation of hydraulic systems is typically implemented to control of water levels and flows in schemes is accomplished by enable easier scheme operation, as opposed to more labor-inten- irrigation operators through a variety of hydraulic control struc- sive manually operated systems.77 Automation is typically favored tures. Flow control enables operators to adjust the flow rate (or in order to minimize potential mistakes of scheme operation. discharge) to equal a target value. Water level control is used to attain target water levels either upstream or downstream of a barrage is a diversion dam structure that regulates and stabi- regulating structure. lizes water levels upstream using its large gates that control the water passig through. discharge (also called flow rate) is the volume of water (or volumet- ric flow rate of water) in cubic feet passing a cross-sectional area canal is an artificial channel for conveying and delivering water of a channel per unit time (ft3/s). It is calculated by multiplying the to irrigated fields from a source. mean velocity with the cross-sectional area. It is calculated by mul- tiplying the mean velocity with the cross-sectional area. Water flow constant flow (or uncontrolled continuous flow) is characterized can change from one state to the other depending on its energy, by the absence of control down all the conveyance and distribu- with each state having a certain combination of velocity and depth. tion networks. downstream control means that the water discharged in each consumption of water (or consumptive use, depletion, evapo- reach of a scheme is controlled from the downstream end, while transpiration [ET]) refers to the amount of water depleted and changes in flow emanate from the tail-end and work sequentially thus unavailable for further use. It is the amount transferred to the upstream though the scheme. A major advantage of downstream atmosphere through evaporation from plant and soil surfaces and control is its short response time, offering a higher degree of through transpiration by plants. When it comes to the water used flexibility. in crop production, the beneficial consumption is represented by the fraction of water use that is transpired by the crop itself. evapotranspiration (ET) is defined as the sum of direct evapora- tion (E) and transpiration (T) of soil water through plant systems and into the atmosphere. 77 There are several options for automation of water control, including: (i) dis- tributed, (ii) centralized, and (iii) supervisory control. With distributed control, flow rate (see discharge) control is achieved through independent automatic units, and the system manager is unable to supervise or control the entire canal system. Centralized gates are structures for controlling of canal water levels and flow control is achieved through a master station and its operation depends on rate. Various types include regulator gates, slide gates, radial the reliability of a communication system used. Lastly, supervisory control gates, or flap gates. Gates may be operated manually, hydrauli- combines distributed automation under a master supervisory control. In this case, a central station makes decisions on the lower-level control strategies cally, or by using power. They can be controlled manually or based on the data received from local controllers. automatically, locally, or remotely. GLOSSARY OF TERMS 93 gravity irrigation takes advantage of and utilizes the natural management and scheduling of irrigation events. Measurement water pressure created by gravity, thereby allowing water to be of volumes helps in verifying that a proper amount of water is distributed over the soil surface by flowing through the path of applied at each irrigation event (ideally at levels not exceeding least resistance. amounts permitted). Flow measurement technologies can be used as standalone (deployed at strategic sites), site manage- gravity-fed irrigation utilizes the natural water pressure created ment, or as network control solutions (providing system-wide flow by gravity; water is supplied from a higher level to the land by measurement). gravity. micro-irrigation delivers water directly to the root zone of plants irrigation scheduling is a process used by irrigators to determine using low-pressure, low-flow-rate type of irrigation equipment. the correct frequency and duration of applying water to crops. offtakes are diverting structures that draw water from the main land leveling (or grading) is a process that grades the field to system to supplies it to the field, representing a point at which an even surface in preparation for planting and use of irrigation control of water changes from the service delivery entity to end schemes. It increases the uniformity by smoothing the soil and users. redistributing it throughout a field to create a ground surface that allows the consistent advance of water across a field. Land outlets are small structures that regulate delivery of water to ir- leveling is commonly applied to mildly sloping land, thereby elim- rigated fields from a distributing canal. inating high and low areas. It is typically accomplished through mechanized grading of agricultural land (based on a detailed programmable logic controller (PLC) is an electronic hardware engineering survey, design, and layout) but can also utilize laser that reads inputs (e.g., on water levels, gate positions, pump land leveling (LLL). speeds) and controls electronic relays that cause structural ad- justments (e.g., gates or pumps moving or turning on). It is also land planing is the process of smoothing out localized soil sur- referred to as a remote terminal unit (or RTU). face irregularities (bumps and depressions) by dragging a special implement across a field. pressurized irrigation schemes utilize pressurized water through pipes or other tubing for delivery and application to crops. long-crested weirs maintain a constant upstream water level. reaches are structures for conveyance and/or storage of water. The water depth over the weir crest tends to be shallow. They are separated by cross-regulators or, in the case of a pipe- measurement helps determine both total volumes of water and line, by pressure-controlling valves. flow rates of water provided to end users. Measuring flow is use- regulating reservoirs (or balancing storage tanks) are utilized ful for estimating irrigation water use and contributes to better 94 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE at interfaces between hydraulic tiers to allow for flexibility of wa- and other devices) at remote points. ter delivery. They are helpful in holding excess flow in instances where the flow provided is more than is required downstream. turnouts are structures that divert part of the water from a larger Similarly, water flows out of the regulating reservoir in times of canal to a smaller one. Turnouts can be concrete canal structures deficit. Regulating reservoirs are commong in modernization of or pipe structures. schemes with upstream control. They are often located at the upstream control With upstream control, discharge is controlled downstream reaches, approximately in the last 25 percent of ca- at the upstream end of the scheme, while water levels are con- nal lengths. trolled at the downstream end by regulating structures or in-line regulation refers to the actions of a controller with a focus on pumps (to maintain a constant water level upstream regardless of maintaining a target water level or discharge (or flow rate). the flow rate). scheduling of irrigation events determines the frequency and water harvesting is the direct collection of rainwater (or rain- duration of water deliveries to fields to optimize production. generated runoff) from a particular area and stored for direct use. surface irrigation is the application of water to the fields at water control is determined by three interrelated elements: (i) ground level. Common surface irrigation methods include fur- the distribution system’s configuration (or layout), (ii) control strat- row,78 border,79 basin,80 or flood.81 egy chosen, and (iii) the hydraulic equipment used. telemetry is the process of automatic measurement, collection, water level control refers to controlling the elevation of water in and wireless transmission of electrical or physical data (e.g, pres- canal networks and drainage ditches through various structures. sure, speed, and temperature) from remote sources to receiving weirs are cross structures that allow for control of water levels equipment. It involves in situ collection of data (through sensors upstream of the structure. withdrawal of water refers to the amount of water removed (or Furrows are narrow ditches dug on the field between the rows of crops to 78 diverted) from a surface or groundwater source. which water is directed. 79 With border irrigation, the field is divided into strips (also called borders or border strips) by parallel dikes or border ridges. 80 Basins are horizontal flat plots of land surrounded by small dikes or bunds that prevent water from flowing into the surrounding fields. Basin irrigation is commonly used to grow crops on flat lands or in terraces or hillsides. 81 With the flood method of irrigation, the entire field is flooded. GLOSSARY OF TERMS 95 TECHNICAL FICHES 96 INNOVATION AND MODERNIZATION | OFF-FARM PIPELINE CONVEYANCE IN IRRIGATION AND DRAINAGE FICHE 3.1 Off-Farm Pipeline Conveyance DESCRIPTION OF THE INNOVATION Pipelines have been used for more than 100 years in irrigation projects. Advances in materials, designs, and on-farm irrigation methods provide new opportunities and require new approaches to pipeline applications. Because there are so many possible variations, the subject is approached by categorizing different needs. Pipelines are widely used in irrigation modernization projects to replace small canals because of their well-documented benefits, such as low maintenance, no seepage, no spills (with some designs), a quick hydraulic response from the head to the end of a pipeline, and the ability to cross variable topography. If designed properly, they can distribute water to multiple users (farmers) with a minimum of dispute or controversy. Their sizes are usually limited to no more than 2 meters in diameter in irrigation projects because of the high cost of larger pipes. Water can either flow into pipelines by gravity, or it can be pumped in. Some pipeline systems provide sufficient pressure at outlets for sprinkler systems; others only deliver enough pressure to supply open ditches. Major avoidable errors that have occurred in some irrigation pipeline projects include the following: 1. Systems can require considerable pumping that is expensive. 2. They are often too small, and therefore insufficiently flexible, to provide good water delivery service to farmers. 3. Pipeline materials and fittings may have been sized to withstand the expected internal pipe pressures, but they prove in- sufficiently robust to withstand the rough treatment typical of transportation, installation, operation, and external soil and equipment traffic loads. 4. Lack of attention to design principles related to air and water hammer problems. 5. Lack of attention to good material and installation specifications and inspections—plus a lack of enforcement of specifications. Some notable aspects of irrigation pipeline system design: 1. When pipelines are used for flexible distribution systems, the flow rates should be determined using demand theory (briefly described below). OFF-FARM PIPELINE CONVEYANCE | 97 2. If pipelines replace ditches or canals that were used by animals for drinking, or by humans for washing clothes and so on, the new design must accommodate such social aspects (and avoid potential conflicts) by providing special outlets for these purposes. 3. Irrigation pipelines fill and empty much more frequently than do urban water pipelines. Therefore, much more attention is needed for details related to air removal (and vacuum relief) and water hammer during fill up. 4. Outlets quickly change from high flows to zero flow, which can cause water hammer and fitting fatigue problems. There are numerous technical details and variations related to irrigation pipeline system design. Some of those details are ex- plained in the following sections. Low-Pressure Conveyance This is a situation in which a pipeline is used to replace a section of a canal, and is used for conveyance rather than distribution. In other words, it does not have very many fittings or outlets. Because it replaces a canal, it must operate with very low friction loss. These pipelines are typically in the 1–2 meter diameter range. “Low pressure” implies pressures of 1–2 meters or less. Pressure rating for low-pressure conveyance pipes: With low internal pressures, the primary concern is almost always the external loading on the pipe and the ability to install the pipe without damage. Thin plastic pipes may have a sufficient pressure rating, but they will deflect, crack, or otherwise fail due to handling and external soil loads. The external loading is especially important if roads, buildings, or rockslides may eventually cover the pipe. Numerous pipeline materials have been used, including RGRCP (rubber-gasketed reinforced concrete pipe), PVC (polyvinyl chlo- ride), and GRP (glass fiber reinforced plastic). Mortar-jointed, unreinforced, concrete pipe and cast-in-place, concrete pipe have largely been abandoned because of problems with cracking in the long term. The choice of materials and the brand of pipe will de- pend on local availability, cost, reputation, pressure rating, ease of installation, and the external load ratings (for example, whether they will deform if a tractor drives over them). Almost every material has certain problems that affect the pipe itself or the joints, so it is important to have qualified installation crews, and to contact existing users of the product to elicit relevant insights about procure- ment, installation, and usage in the field. Large-diameter, plastic, corrugated pipes have become popular for low pressure because they can have excellent external load rat- ings (albeit only 0.4 atm internal pressure ratings). Some double- or triple-walled HDPE (High Density Polyethylene) corrugated pipe can have problems with the gasketed joint leaking unless the pressure is released at least monthly. Newer similar corrugated pipe with a polypropylene exterior is available for which the gaskets are rated at 0.4 atm continuously. It must be noted that the internal pressure ratings provided by the manufacturer are often for the gasketed joint—but not under continuous pressure. 98 | OFF-FARM PIPELINE CONVEYANCE 1: Triple-wall HDPE corrugated pipe. 2: Triple-wall, double- gasketed Sanitite® polyethylene/ polypropylene pipe. 1 2 Common uses are: 1: A canal built on the contour on a hillside. Difficult to access, and soil 1. Replacement of a canal section on a very steep from the hillside continually slumps into the canal. If there is enough slope that is likely to fail due to seepage losses hydraulic slope to replace the canal and/or debris falling into it from further up the with a pipeline, those problems can be slope. eliminated. 2: Manual trash rack before canal enters a pipeline in an urban area. The canal can easily overflow 2. Conveyance of water through urban areas. This if the trash is not removed from the is an excellent solution to minimize trash prob- screen frequently. 3: Larger screens lems, and for improved safety (fewer drownings require less frequent cleaning. 1 of people and animals). Key points are: n The pipeline entrance must be designed to 2 3 prevent people, animals, or trash from enter- ing it. If all the canal flow enters a pipeline, there is no side current that can sweep away the trash. Therefore, all the large trash that approaches the pipe inlet must be removed. n Manual trash racks are often used, but they require frequent cleaning if the water has a lot of trash. OFF-FARM PIPELINE CONVEYANCE | 99 n Automatic trash racks remove (lift) the trash from the screen and deposit it be- hind or to the side of the screen. There are numerous designs available. One of the most critical considerations is the ability of the device to work well if the water carries sand—which can damage bearings. n Automatic trash screens that are suitable for the end of a canal—where it transitions 1 2 into a pipeline—require reliable electricity. If the pipeline diverts only a portion of the 1: Automatic coarse trash rack in front of a pipeline entrance—screen is static, brushes move. 2: Automatic rotating trash screen—screen rotates like a conveyor belt, trash drops at rear. canal flow, other designs are available that are static or are water-powered. Low-Pressure Conveyance Pipelines with a Limited Number of Outlets Low-pressure conveyance pipelines, as described earlier, typically consist of a segment of an upstream controlled canal. Both ends are open, and the flow that enters the pipeline exits from the downstream end. However, there may be a need to supply water to a few side outlets. The water must be raised high enough at these outlets that a flow can exit with enough pressure to overcome friction loss, as well as to provide controllability. Just as with upstream controlled canals, “check structures” are needed within the pipeline. The figure below shows a box, within which is a wall and flashboards to raise the water level. A sluice gate is also installed in the wall to pass most of the water, leaving only enough water over the flash- boards (weir) for water-level control. The control could be improved by using Irrigation Training & Research Center (ITRC) flap gates (a non-proprietary gate that is locally constructed but which requires a sufficient drop) or by using a longer box with a long-crested weir. It is difficult to properly program and tune a PLC-controlled automatic gate in a box to provide good, stable control because there is little open surface area; the gate must respond very quickly to flow changes. The diagram below illustrates the conceptual hydraulics of this type of pipeline. For low-flow rates, the pipeline would only flow partially full. Even at higher flow rates, the pipeline pressure may not raise the water level in an outlet above the ground surface. Therefore “check structures” of some type are needed just downstream of the outlets to raise the water level so that water can exit the outlets. 100 | OFF-FARM PIPELINE CONVEYANCE The vertical distances between the hydraulic grade line (HGL) and the pipeline indicate the pressures at all points. The diagram below shows that the pressures are different at different locations along the pipeline, and they also change with time as the flow rate changes. Hydraulic grade (pressure) line 1 2 for high flow Hydraulic grade (pressure) line for low flow At low flows, sections of the pipe may flow partially full on steep slopes Outlet Check structure to raise water level above outlet High-Pressure Conveyance Pipelines These are fairly simple and well-understood civil engineering projects, assuming that the flow rate has been properly identified. The innovations are predominantly in having a wide variety of pipeline materials to choose from. The selection should be based on the combination of cost, ease of handling and installation, the availability of fittings, pressure rating, and water hammer (surge pressure) considerations. Pipelines smaller than 0.8 meters in diameter are usually made of PVC or HDPE (solid wall) pipe. HDPE and other materials (including rubber-gasketed reinforced 3 concrete pipe) are typically used for larger pipe diameters. 1: Conceptual side-view of an open, low-pressure conveyance pipeline on steep ground, with a few outlets. (Note: Not drawn to scale. Does not show required air vents.) 2: Example of a check structure box on a low-pressure conveyance pipeline. 3: Gasketed belled end of a PVC pipe. OFF-FARM PIPELINE CONVEYANCE | 101 Pipeline Distribution Systems (Off-Farm) Pipeline distribution systems differ from conveyance systems in that the latter deliver to multiple outlets and, thereby, may use differing flow rates at the inlet and outlet. Furthermore, flow rates may frequently change in a pipeline, although it is desirable to maintain constant outlet flow rates once they are set. Many of the old, very low-pressure, pipeline distribution systems were made of unreinforced concrete (cast at a local factory) or cast-in-place (monolithic) concrete pipe. Both concrete systems had good external loading characteristics, were produced locally, did not require fittings—a hammer and mortar and pieces of pipe could be used to configure any elbow or outlet—and served their purposes well for several decades. However, eventually these systems began to suffer from extensive cracks due to heavy equipment loads, exposure to cold water in the spring, and land subsidence. These old pipeline systems are being modernized, and new pipeline systems are being installed, using plastic pipelines. (When most of the low-pressure, concrete pipelines were installed, plastic pipe was not yet available.) A relatively new trend is to replace canal/ditch distribution systems with pipeline systems. The design and material selection for these modernized systems requires a variety of considerations, some of which are noted below. Pipeline Distribution Systems (Off-Farm) on Steep Downhill Sloping Ground For a long distribution pipeline on downhill sloping ground, there are three design choices for pressure control within the pipeline itself: Choice 1: Design as an upstream controlled canal, but in an “open” pipe This was required with early, piped, irrigation distribution systems because plastics were not yet available, and steel would corrode. The concrete pipe that was affordable could not withstand more than approximately one atmosphere of pressure without leaking at the joints. Being upstream controlled, and without a reservoir on each pipeline, they were typically managed on a rotation delivery schedule. The flow rate into the pipeline was adjusted and controlled at the inlet; the complete flow rate was delivered to one outlet at a time. If a project can only afford low-pressure, corrugated polypropylene (or similar material) pipe with gasketed joints (that are limited to about 0.4 atmosphere of pressure), check structures must be used to minimize the pipeline pressure. This was described earlier in the discussion of low-pressure conveyance pipelines with a few outlets. 102 | OFF-FARM PIPELINE CONVEYANCE But there is a major difference between a conveyance pipeline and a distribution pipeline. For a conveyance pipeline with a few side outlets, almost all of the flow exits the downstream end of the pipeline and flows into a canal or pond. By contrast, for a distri- bution pipeline, all the water is supposed to depart from controlled outlets—with no spill at the downstream end. This means that, to avoid spill at the downstream end, a low-pressure pipeline on a long downhill-sloping topography must operate just as an upstream controlled canal—with limited flexibility. Open boxes with check structures, situated in the pipeline just down- stream of outlets, are required for two reasons: n The open box prevents the pressure from exceeding the height of the top of the box. If the pressure exceeds it, the box will overflow. In the earlier example with this design in a conveyance pipeline, this was not a problem—most of the water was in- tended to continue downstream past the pipeline. But for a distribution pipeline, if the inlet flow exceeds the sum of the outlet flows, the box with the lowest elevation will overflow. n The check structure in the open box enables operators to raise the upstream water level sufficiently to make deliveries to upstream outlets. Choice 2: Design as a closed pipeline Closed pipelines have these characteristics: n There are no open “check structure boxes.” n The pipeline remains full all the time. n If there is no flow rate, the pressure on the downstream end equals the elevation change between the canal source and the downstream end. n The flow rate is not controlled by a valve at the inlet to the pipeline. Rather, it is controlled by the total flow of all the outlets. There is no need to manually balance the flows by properly adjusting the inlet flow rate. n Pressures at the outlets will vary considerably as various outlets are turned on and off. n The operators must verify flow rates or water orders to ensure that the maximum number of outlet flows does not exceed the pipeline capacity and does not require too high a flow rate from the canal. n Because the pressure varies so much, unless there is a huge drop in elevation, there is rarely enough consistent pressure for drip or sprinkler irrigation. However, some farmers use electric pumps with variable frequency drives (VFDs) that automatically add as much—or as little—extra pressure as needed to supply their pressurized irrigation systems. n There is no spill from the pipeline. n If the pipeline operates flexibly, the water source (usually a canal) must provide that flexibility in water delivery service. OFF-FARM PIPELINE CONVEYANCE | 103 The diagram on the right shows the hydraulic grade lines (HGLs) of a closed pipeline under HGL at no flow Pressure on Outlet #2 at no flow into pipeline HGL three flow-rate conditions on a downhill slope. for e ither Outle t #1 o r #2 open Choice 3: Design as a “semi-closed” pipeline HGL for only Outlet #1 open Supply that uses float valves instead of check struc- canal On/o valve tures in the open boxes and flow measurement HGL for o nly O device. Valve is completely utlet #2 o closed or open pen The float is positioned on the downstream side Outlet #1 of the valve, providing the same flexibility as ca- nal downstream control, but with low-pressure Pipeline pipeline materials. Old French and American pipeline systems sometimes used this option, Outlet #2 but they are no longer recommended because of their complexity, susceptibility to becoming Conceptual pressures at three different flow conditions in a closed distribution pipeline. Downhill pipe slope. clogged with trash, their cost, and the availabil- ity today of strong plastic pipeline materials. There is one special design consideration for steep, downhill pipelines. If most of the outlets have electric pumps and power out- age occurs, there will be extreme water pressure surges (water hammer) when all the pumps shut down at the same time. Several solutions to this are provided at http://www.itrc.org/reports/waterhammerprotection.htm. Pipeline Distribution Systems (off-farm) on Downhill Mildly Sloping Ground These pipeline systems are almost always closed pipelines because of the ease of management. Pipeline Distribution Systems (off-farm) on Flat or Uphill Ground Pipeline distributions on flat ground are sometimes pressurized by gravity—if the pipeline distances are short and the canal water surface is higher than the ground surface. But pipeline distribution systems typically need to be pressurized in some way. Various options are discussed below. Flat Ground and Relatively Short Distances (≈1 km or less): Low-Pressure Deliveries to Outlets This option is typically solved with a pump that discharges into an open stand, which supplies a pipeline. The open stand prevents water hammer on startup, eliminates the need for special valves, and will provide automatic pressure relief (will overflow) if the 104 | OFF-FARM PIPELINE CONVEYANCE downstream demand is less than the pump discharge. The figure on the left shows such an application into a concrete stand. The pipeline is PVC. The installation is missing a flow meter, but by providing some pressure at the inlet to the pipeline, the flow can reach the end of the pipeline. If the open turnout (outlet) is at the downstream end of the pipeline, the water rises in the open stand to overcome the friction. If the open turnout (outlet) is near the open stand, the water level in the open stand is very low because very little friction must be overcome. This design is ideally suited to a simple delivery schedule that provides water to only one outlet at a time. Because only one outlet is open at any time, it will receive the full flow of the pump. This can be suitable for surface irrigation. The pump always has the same discharge pressure, and therefore the same 1: Low-pressure pump discharging into an flow rate. The pipeline can replace open stand that supplies a low-pressure hard-to-maintain ditches and elimi- pipeline. 2: Conceptual sketch of low-pressure nate seepage loses. Furthermore, pipeline distribution system on flat ground. 1 there is almost no time lag be- tween turning on the pump and 2 being able to deliver water to any outlet. Note that in the two figures on the left there are no valves on the G.S. pump discharge pipe. This is be- cause low-pressure vertical pumps are typically of a mixed flow or axial flow design. With those specific impeller designs, if a valve is partially closed to reduce the flow, the amperage input (electric current) to the motor will increase and could easily burn out the motor. If a variable flow rate is required, the least expensive method is to have an overflow from the stand, back to the canal. This can be done if there are variable flowrate demands downstream. Another, more complex, option using these types of pumps is to use a variable frequency drive controller on the pump motor—but typically the complexity and cost are not warranted on these small kW motors. Farmers who need pressure for their sprinkler or drip systems often use portable engines and pumps on trailers to boost the pres- sure at their outlet. This is especially common in areas where sprinklers are used for only a few weeks to germinate a crop, and subsequent irrigations are with surface methods. OFF-FARM PIPELINE CONVEYANCE | 105 1: Portable pump with diesel engine on trailer. Fuel tank is below the engine. 2: Portable pump and engine on a trailer that pumps water from a canal into a solid set sprinkler system irrigating 1 2 lettuce. The pressure rating of the pipe and fittings must be high enough for the pipe wall thicknesses to avoid damage due to tractor traffic, transportation, and handling. In general, with PVC pipe, the pressure rating must be at least 6 atm for large-diameter pipe (200 mm and greater), and 8 atm or more for smaller-diameter pipe. Flat Ground and Relatively Short Distances (≈1 km or less): High-Pressure Deliveries to Outlets For this application, a pump is needed to overcome friction in the pipeline, and also to provide the high pressure to the outlets. An open stand and low-pressure pipe are not options; the pump must be directly connected to a pipeline that is typically rated at least for 6 atm. The short distance implies that the flow rate is relatively small. Therefore, it is typical to use just one pump. The pump should be selected to have a relatively “flat curve” (flat performance curve). This provides two benefits: 1. Although the pump pressure will rise if the discharge flow is reduced, it will not rise too high and therefore will not destroy the pipe and fittings. 2. As the flow rate decreases, the input kW to the pump will also decrease. Engine-powered, horizontal centrifugal pumping from a canal. The blue box on the inlet is an automatic priming device. 106 | OFF-FARM PIPELINE CONVEYANCE A relatively flat curve is shown on the left. This is for a horizontal centrifugal pump 40 342.9 mm 90 that would need to be primed before starting it. This pump would operate with 35 89.7 80 greater than 80 percent efficiency between about 800 and 1,200 liters per minute. 70 30 60 Operators for this type of pump would be instructed to start it with the discharge Head – m valve (on steel pipe at the pump outlet) closed, and then slowly open it to avoid % – Efficiency 25 50 20 40 water hammer damage to the pipeline. The total pressure of the pump would not 15 30 exceed about 42 meters of pressure. 10 20 Pipeline Distribution System for Uphill or Long Flat Distances 5 10 0 75 0 For these systems, the pipelines must be of the “closed” design because open Power – kW 50 25 stands would be too tall due to the higher pressures. There is always a question of 0 what pressure should be supplied to the outlets, but pipe pressure is always too 100 200 300 400 500 600 700 800 900 1000 1100 1200 lpm x 10 high to consider low-pressure pipelines. Because of pipeline friction and elevation changes, it is impossible to provide the same pressure to turnouts everywhere along the pipeline (unlike the earlier scenario with downhill pipes). Multiple pumps are often used in parallel to supply a wide range of flows. There are various means of controlling the flow into these pipelines: 1. The flow is manually adjusted at the pump discharge. The number of open outlets must then be carefully managed to ap- proximately match the target pump discharge pressure. 2. The pump flow is automatically varied to meet downstream outlet demands. This is accomplished by automatically varying the number of pumps that are operating at once—and/or changing the pump speeds—to maintain a target pipeline pressure at some point. There are two choices for locating the target pressure: a. Immediately downstream of the pump. This requires a constant high discharge pressure from the pumps. This consumes more energy than the next option. However, it is relatively simple because the distance between the pressure sensor and the pump controllers is short, and therefore there are few problems with communications between the sensor and the controller. b. Near the highest, most distant point in the pipeline distribution system. By maintaining a target pressure at this most distant point, the discharge pressure of the pumps will be able to decrease as the system flow rate requirement decreas- es—thereby saving pumping energy. The only downside to this is the need for a communications link between the distant sensor and the pumping station. OFF-FARM PIPELINE CONVEYANCE | 107 In all cases, the design must consider potential pipeline damage from water hammer caused by pumps starting and stopping. A variety of solutions are available, including elevated tanks, surge tanks, quick-release pressure relief valves, or slow-opening and slow-closing pump discharge valves. Air/vacuum release valves are also needed. Agricultural pipelines need more, and larger, air valves than do typical urban pipelines, because agricultural pipelines tend to be filled and emptied more frequently. Outlet Designs The operational features of outlets on pipeline distribution systems include the following: 1. A flow measurement device, usually incorporating a measurement of accumulated volume 2. An on/off valve 3. A flow adjustment valve 4. Perhaps the following features: a. A pressure regulator b. A flow limiter device c. An air vent d. A pressure relief valve High-pressure Systems There are a variety of manufactured combination units used in southern Europe (Balbastre-Peralta, I. et al. 2021).1 They are typically designed for small outlets. The images below are from Balbastre-Peralta et al. 2021. A similar concept was attempted in the AguasCalientes Distrito 0001, Mexico irrigation project, but failed because of the complexity and the amount of experimentation by local suppliers that was involved. That hydrant included automated injection of fertilizers into the pipeline. A major concern for such units is the high loss of pressure (about 50–150 kPa). The study in southern Europe by Balbastre-Peralta et al. also found that about 29 percent of the valves had malfunctioned, and an additional 29 percent were defective because of dirt/ trash. The flow/volume metering was particularly sensitive, to the point that many projects in Southern Spain ignore the volumetric readings and instead bill on acreage and crop estimates. 1 Balbastre-Peralta, I. et al. 2021. “Multioutlet Hydrants in Mediterranean Pressurized Irrigation Networks: Operation Problems and Hydraulic Characterization.” Agronomy 11: 2240. https:// doi.org/10.3390/agronomy11112240 108 | OFF-FARM PIPELINE CONVEYANCE 1: Multioutlet hydrant with a gate valve, mesh filter, water meters, and electrovalves to control each plot. 2: GIS analysis of multioutlet hydrant distribution on a pressurized network system in Segorbe, Spain. Irrigable area of 72 ha (102 plots), with an average area per plot of 0.7 ha. Colored field plots correspond to each hydrant. Irrigation hydrants up to 3–4 inches (75–100 mm) are also available with prepaid card control. Larger outlets (turnouts) in North 1 2 America are rarely purchased as pre-assembled units. Most irrigation turnouts are in the 6–18 inch (150–450 mm) diameter range. They are assembled with individual components that are selected for their individual qualities. Significant attention is paid to low-pressure losses through the individual components, and therefore through the complete hydrant/outlet. The assemblies often include: n Full-bore (spooled) magnetic meters with no required upstream and downstream straight-pipe distances; these meters are now taking the place of propeller meters because of their high accuracy, ability to measure both flow rates and volumes, low losses of pressure, and absence of moving parts that can become clogged. Batteries can last for more than 10 years. n Large pressure regulators with relatively small pressure losses. These typically use large pilot valves that provide excellent ac- curacy, as opposed to large, spring-loaded, mechanical pressure regulators. In frigid climates, the pilot valves must be cleared of water during the winter. n The assembly typically includes both large-volume air exhaust/vacuum relief valves, and continuous acting air vents. Flow limiters are rarely used in North America. Also, the philosophy of control and flexibility in North America is different from what is often found in southern Europe and Australia. In those regions, there has been an emphasis on centralized remote control of the on/off valves based on some preprogrammed schedule. In the United States, the emphasis has been on designing canal and pipe- line distribution systems that provide highly flexible deliveries without needing to know flow rates at the individual outlet, turnout, or hydrant. OFF-FARM PIPELINE CONVEYANCE | 109 1: An outlet with manual flow and pressure control, but volumetric and flow-rate metering. Newer magnetic meters provide accurate results with much shorter before/after straight-pipe lengths. 2: An outlet with an emergency on/off valve followed by a flow meter (turquoise), pressure regulator, and flow- 1 2 rate adjustment valve. Low- to Moderately-Low-Pressure Pipeline Systems Irrigation outlets from moderately-low-pressure pipeline distribution systems that supply surface irrigation systems present a special challenge. A typical outlet will have an on/off valve, a flow adjustment valve, and a flow meter. As with high-pressure systems, full- spool magnetic meters are now usually the preferred flow meter. The challenge occurs with pressure regulation. With moderately low pressures in the pipeline, every time an outlet is opened, closed, or adjusted, the pressure (and therefore the flow rate) at every other outlet along the pipeline changes. The pressure changes can be 50 percent or more. The field surface irrigation then becomes unpredictable as the flow rates constantly change. The pressure regulation valves that are suitable for high-pressure systems are typically unsuitable for these low-pressure situations because (i) economically priced valves are usually too small for the large surface ir- rigation flows; and (ii) the standard pressure regulators have too much pressure drop. The image on the right illustrates a design that uses float valves at each of the 900+ outlets of the Delano-Earlimart Irrigation District in California. It provides a constant flow rate at a low pressure suitable for surface irrigation. It also provides very slow shutoff, which is important for avoiding water hammer when farmers connect to the stand with booster pumps for drip and sprinkler irrigation and the electric power fails. A float valve installed in the equipment yard of the Delano-Earlimart Irrigation District to show farmers how they are operated. Source: http://www.itrc.org/reports/deidfloatvalve.htm 110 | OFF-FARM PIPELINE CONVEYANCE Side view of a float valve. The float is inside the stand; the linkage moves a butterfly valve (on the inlet pipe) by about 70 degrees and can completely and slowly shut off the valve. Pipe Sizing for Demand Operation Pipe sizing, once the flow rate is known, is relatively simple. It involves the balancing of the hydraulic requirements of elevation change, friction, and available pressure at the inlet. But the design principles behind properly determining irrigation distribution pipeline flow rates are new to almost all engineers. Knowing what flow rate to use in each pipe segment requires a special computational procedure. The theory for sizing pipelines that operated “on demand” was first developed by R. Clement (1965) in France. His theory enabled a designer to properly determine the flow-rate capacity of every pipe segment on a multiple-outlet distribution pipeline. The variables he considered were: 1. The flow-rate capacity of the outlet. 2. The flow rate needed at the outlet to meet the gross crop irrigation requirement if irrigation were continuous (24 hours a day, seven days a week). 3. The fraction of time available for irrigation. For example, farmers may not irrigate on a Saturday or Sunday, or may irrigate only during daytime hours. 4. Allowable probability of no congestion. This considers the probabilities of various numbers of outlets being opened at the same time. 5. The number of outlets downstream of the pipe segment in question. Since then, the computation procedure has been modified and has been successfully used for both canal and pipeline projects. The Food and Agriculture Organization (FAO) 2007 publication 59, Performance Analysis of On-Demand Pressurized Irrigation Systems, is recommended as a reference. The three examples below illustrate how, for the same crop and irrigated area, a designer could use three entirely different flow rates along the same pipe segments. The long and short of it is that a designer needs to fully understand on-farm irrigation water delivery requirements to properly size distribution pipelines. The three examples all assume the same gross peak irrigation requirement per month, in terms of volume required per month. They also assume that each outlet serves an identical number of hectares. They differ as follows: OFF-FARM PIPELINE CONVEYANCE | 111 Example 1: Continuous flow. All turnouts are sized so that they deliver the same flow rate, 24 hours per day, seven days per week, during the season with peak evapotranspiration (ET). This provides the least expensive pipeline system but gives farmers absolutely no flexibility or margin for error. It is completely incompatible with surface irrigation, which requires periodic but large flow rates. It also allows no downtime for tractor operations in the field, spraying, or repairing broken irrigation components. Example 2: Rotation deliveries. All the flow into the pipe is delivered to only one outlet at once, but for short durations. This was sufficient for older surface irrigation systems, but again provides no flexibility. The flow must be utilized when it arrives, whether or not it matches the crop and soil water requirement. It is incompatible with any pressurized on-farm irrigation method. Example 3: On-demand deliveries, with some maximum outlet flow rate. The outlet flow rate provides flexibility to the farmer and is between that needed for continuous and rotation deliveries. In this case, the outlet flow rates were assumed to be twice what is needed for continuous flow. The probability of no congestion is assumed to be 97.5 percent. Continuous Rotation Demand Maximum Relative Minimum Relative Water Delivery Relative Flow Rate 10 10 16 Pipe Segment Pipe Segment 1 10 2 Service of All Outlets Flow Rate Flow Rate 9 10 16 1 10 2 8 10 14 Continuous 1 10 2 7 10 12 No flexibility. Unsuitable for 1 10 1 1 10 2 6 10 12 surface irrigation 1 10 2 5 10 10 1 10 2 Rotation 4 10 8 No flexibility. 1 10 2 Unsuitable for 10 10 10 3 10 6 1 10 2 pressurized irrigation 2 10 4 1 10 2 1 10 2 Demand 1 10 2 Flexible 2 2 16 Two important points emerge: 1. In the examples, the cost for the rotation and demand pipelines would be about the same. 2. If the pipelines were much longer and had more outlets, the inlet flow to all the pipelines would be about the same. 112 | OFF-FARM PIPELINE CONVEYANCE WHAT BENEFITS CAN THIS INNOVATION BRING? Pipelines are most beneficial under the following circumstances: 1. Conveyance of water through urban areas, where there are problems with canals such as trash thrown into them and drownings. 2. Replacement of canals that are on steep hillsides, and which are subject to canal bank failure as well as debris filling them up from rockslides. 3. Smaller pipelines (typically less than about 0.50 CMS) which supply groups of fields and farmers. Small ditches and canals are extremely difficult to maintain properly, often have large seepage losses, remove land from production, introduce weed seeds, and are difficult to control. Properly designed pipeline distribution systems can eliminate those problems. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? It is usually impractical to replace larger canals (greater than 2 CMS) with gravity pipelines because of the high cost of the latter. The advantages of smaller pipelines, mentioned previously, are numerous, so the cost comparison is not reducible to the installation cost of a ditch/canal versus that of a pipeline. One must additionally consider the broader costs and benefits of maintenance, extra land, cleaner water, and so on. One of the biggest problems with pipelines can be the long distance from the manufacturing source, increasing delivery times and costs. A second problem is the difficulty of locally sourcing maintenance, equipment repairs, and expertise. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Numerous specifications are available from standards groups such as ISO (Europe) and ASTM (United States). Those standards tend to focus on testing and on the components, characteristics, and dimensions of pipelines and fittings. Technical documentation with design specifications available from various industry groups typically includes details about deflections, loading, water hammer, and so on. Examples: n The Plastics Pipe Institute Handbook of Polyethylene Pipe. https://plasticpipe.org/Shared_Content/Shop/PE-Handbook.aspx. n Handbook of PVC Pipe Design and Construction. https://www.uni-bell.org/Resources/Handbooks. n Concrete Pipe Design Manual. www.concrete-pipe.org. OFF-FARM PIPELINE CONVEYANCE | 113 Various government agencies also have specifications that provide some details on backfill materials, allowable temperatures dur- ing installation, and so on. Example: n Natural Resources Conservation Service. Conservation Practice Specification. Irrigation Pipeline Plastic Pipe. Code 430PP. (Note: Other pipeline materials are covered under Code 430.) In some developed countries, the best comprehensive specifications for materials, inspection, installation, and so on are developed by consulting engineering firms. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING The design must be performed by individuals with excellent experience in the design, installation, and maintenance of pipeline sys- tems. The hydraulic calculations of friction loss and pressures are important, but they represent only a small fraction of the expertise needed. Designers must understand the practical details of fittings and their strengths, materials, air vents, load-bearing strengths, and installation details such as temperature control, bedding, and thrust blocks. A good design will always be accompanied by installation details, required material standards to be met, inspection requirements, and sample agreements for the resolution of conflict during installation and commissioning. For off-farm distribution systems, the designer must be aware of the various approaches for determining flow rates in pipe sections, based on demand theory and the on-farm irrigation system turnout requirements. This requires a combination of on-farm under- standing plus the more typical civil engineering disciplines. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Although many pipeline distribution systems are gravity-fed, there are many instances in which some level of pressurization is required—to reduce the size of the pipes (if there is no ground slope), to provide some pressure to outlets, or to move the water uphill. In those cases, pumps are required. The pump station must usually be designed to provide flexible water delivery, depending on the downstream demand. This requires a careful pump station design as well as a water supply source that is flexible—requiring reservoirs or very flexible canal systems. Training and local standards development are always important components of pipeline projects. 114 | OFF-FARM PIPELINE CONVEYANCE LINKS Many different materials and manufacturers are available, and some market and technical research will need to be done for each project and location. Due to rapid changes in the field over the past decades, standard design handbooks are often partially obso- lete, and designs are best made by consulting engineering firms. Some relevant links: Balbastre-Peralta, I. et al. 2021. “Multioutlet Hydrants in Mediterranean Pressurized Irrigation Networks: Operation Problems and Hydraulic Characterization.” Agronomy 11: 2240. https:// doi.org/10.3390/agronomy11112240 The Plastics Pipe Institute Handbook of Polyethylene Pipe. https://plasticpipe.org/Shared_Content/Shop/PE-Handbook.aspx Handbook of PVC Pipe Design and Construction. https://www.uni-bell.org/Resources/Handbooks Concrete Pipe Design Manual. www.concrete-pipe.org Evaluation and Modification of a Float Valve for the Delano-Earlimart Irrigation District. http://www.itrc.org/reports/deidfloatvalve.htm OFF-FARM PIPELINE CONVEYANCE | 115 FICHE 3.2 Flow Measurement and Control to Outlets (in Canals) BRIEF DESCRIPTION OF THE INNOVATION This fiche discusses the wide variety of pipeline flow rate measurement devices and the special considerations needed for small gravity outlets of 0.5–10 CFS (.015–.30 CMS). WHAT BENEFITS CAN THIS INNOVATION BRING? Flow measurement and control at outlets enables canal operators to know and control where their commodity (water) is going—a fundamental concept in process control. It is also an essential tool for good on-farm water man- agement. If water is sold on a volumetric basis, measurement is required; this also extends to any program of volumetric water allocation. Magnetic meter on a well pump discharge. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? With today’s technologies and engineering knowledge, flow measurement and control can be achieved in all situations, if project managers and farmers want good flow measurement and control. DESCRIPTION OF THE INNOVATION While flow measurement devices are available for all situations, not all flow measurement devices are applicable for all situations. For example, if the outlet supplies a sprinkler or drip system (regardless of whether the outlet itself is pressurized), the flow rate through the outlet is not precisely predictable and can vary with time. This is because sprinkler and emitter pressures can vary, nozzles and emitters can plug over time, different blocks within a field typically have different flow requirements, filters need to be flushed, etc. The water delivery system must be flexible enough to provide these flow variations automatically, and the flow rate cannot just be set and remain constant (as is typical with surface irrigation). The exception would be if an outlet supplies an on-farm reservoir that can provide a buffer between the delivery system and the field irrigation system. 116 | FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) Drip and Sprinkler Irrigation Flow Measurement As seen in the “Considerations” table below, the applicable flow meters for drip/sprinkler systems also measure the volume of water that has been delivered. The flow meters of choice for these pipeline installations are typically the following: 1. Full bore (spool) magnetic meters. These are becoming the most popular units in modernized systems because they have no mov- ing parts, can be very accurate, have little or no pressure loss, are not damaged by sand, and do not plug with trash. No devices 1 protrude into the flow path. A few manufacturers have special internal configurations that allow the meters to be installed with no 2 straight pipe length requirements either upstream or downstream. Some manufacturers also offer batteries with a life of about 10 years. There are major differences in quality between manufactur- ers—even if their literature promises identical performance. 2. Propeller meter (spool, vertical, and saddle configurations). These have been used for decades and have provided excellent service if the water is clean, if the bearings are replaced every few years, and if they are mounted properly with sufficient straight pipe sections upstream and downstream. Sandy water destroys the bearings quickly on many 3 models. 4 1: Magnetic meter on irrigation district outlet, in buried vault. 2: Propeller meter (turquoise color) outlet from a pipelined distribution line, directly feeding a drip system with a booster pump. 3: Saddle propeller meter on the discharge of a drip filter system. 4: Vertical propeller meter, viewed from downstream. The pipeline must be kept full. FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) | 117 3. Ultrasonic, transit time, and acoustic meters. These units are available on the mar- ketplace, but are typically not yet very common nor time-tested for agricultural outlets flow measurement. They use various electronic signals (other than magnetic fields) that transect the flow path and provide an electronic display of the flow rate. Some appear to be quite promising. 4. Insert paddlewheel flow meters. In general, these have not been successful because they only sample the velocity in a small region of the pipeline, and the bearings and paddlewheels themselves are often not robust. They require long straight sections of pipe and very clean water. 1 5. Multioutlet hydrants. These are a special category, and are common in the 2 Mediterranean region for pipeline distribution systems that serve small fields. They typi- cally have multiple functions of pressure regulation, on/off, flow rate measurement, and may have flow limiting valves. Balbastre-Peralta et al. (Agronomy 2021, 11(11), 2240) de- termined that although the hydrants typically meet the European Standard EN 14267, the standard is insufficient to guarantee good quality. Pressure losses range from 50–110 kPa. The phenomenon of turbine flow meter damage in many systems is a significant problem, and is leading to massive changes in multijet water meters, or to the complete elimination of the measurement of water consumed and a return to billing by crop or acreage. 3 Surface Irrigation Flow Measurement Options used for surface irrigation flow measurement include: 1. Large diameter propeller and magnetic meters. These were discussed above. 2. Weirs and Flumes. These are located downstream of an on/off plus flow control gate. There are numerous options that can be found in many books. They can be very accurate over a good range of possible flow rates. They typically fail when designers assume that 1: Multi-outlet hydrant from Spain (Source: Balbastre-Peralta et al. (2021, the downstream channels will be maintained properly, when in reality they become silted 2240)). 2: Broad-crested weir (flume) or full of weeds and the weir or flume is submerged excessively on the downstream side. in a slip-form canal, with flow gauge A major limitation is the amount of head loss (water level drop) they require for control upstream. 3: Broad-crested weir (flume) in an empty slip-form canal, with stilling through the gate plus measurement of the weir or flume—typically a minimum require- well upstream. ment of 30–60 cm drop. Flumes inherently require less loss in head than do weirs. 118 | FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) 3. CHO. The poorly named “Constant Head Orifice” consists of a pre-cast concrete ORIFICE (UPSTREAM) TURNOUT (DOWNSTREAM) GATE GATE box with two gates in series. The first gate is a flat-bottomed sluice gate installed SUPPLY CANAL INLET ENTRANCE SECTION 7 4 MIDDLE SECTION DOWNSTREAM 5 in suppressed walls and on a suppressed floor (no gate frame protrudes into the 8 flow). The opening is manually positioned (based on a table) to have a specified 2 2.0 FT MIN ROAD AH=0.3 FT water level drop across the gate (e.g., 8 cm) for the target flow rate. The on/off 3 and flow rate adjustment is accomplished with the second, downstream gate. 11 Y = U/S DEPTH PIPE While this has been successfully used in many projects and is very simple, it 1.0 FT W= has often failed in international projects because operators are not taught how 3.0 FT 9 GATE OPENING 9 12 to operate the structures, and they may not even have any rating tables. The CHO – SLOPING INLET SIDE VIEW concrete boxes should not be constructed in the field, but rather be of pre-cast 9 8 8 9 concrete. Water-tight gates should be used for the downstream gate. Special AD 3.0 FT RO 2.0xB MIN 1.5xB MIN round gates, called “canal gates,” are manufactured in many countries, and are 11 B very robust and seal very well against leakage because they have a special 1 1.0xB MIN 6 10 8 wedge configuration that forces the gate plate against the frame when closed. 9 8 9 CHO – SLOPING INLET PLAN VIEW 1 4. Metergate. This is a single standard round “canal gate” that has a stilling well located a specific distance downstream on a piped discharge. The pipe may only be 5–20 feet long and is typically used to convey water under a ditch bank. Operators have a table that shows choices for gate openings versus difference in water level (between the canal and the stilling well). The operators will open the gate and measure the head difference, and then check the flow rate in the table. They will then re-adjust the gate opening until the combination of gate opening and head difference corresponds to the target flow rate. Operators 2 usually need a few hours of practice to learn how to do this at first. Metergates are within +/-6% accuracy if they are constructed properly and if the pipe is kept full. The complete structure should be of pre-cast concrete, with a good com- mercial canal gate. 1: CHO drawings. 2: Metergate upstream of a long-crested weir, supplying rice water. 3: Precast concrete metergate box discharging into a corrugated, polyethylene pipe for a road crossing. 3 FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) | 119 Height above A sill level Nominal level Height above A sill level Nominal level 1 B B Q +/- 10% Q +/- 5% Q +/- 10% Q +/- 5% Range Range Range Range C C Nominal Q Q + 10% Nominal Q Q + 10% Q - 10% Q - 5% Q + 5% Q - 10% Q - 5% Q + 5% 2 3 5. Distribution module. Distribution modules were developed in the old USSR and in France many decades ago. When installed at an outlet to a field, that unit will deliver one pre-designed flow rate to a field. The operation is sim- ple—it is open, or it is closed. Two different designs provide different levels of “pressure compensating” ability, in that, as the supply canal water level changes, the flow rate stays about the same. Water levels in the canals must stay reasonably constant to keep within the operating range. The primary adaptation of this design has been in the Mediterranean region and Iran, but there are manufacturers in other countries, such as Brazil. The vertical (eleva- tion) installation of these modules must be accurate, and they cannot be submerged on the downstream side. Multiple parallel modules can be used to obtain a wider range of fixed flow rates. 6. Automated gates that control water level over a weir or flume. These are 4 rarely used for field outlets because of their cost and complexity. The tech- nology is certainly available and widely used—but for larger canals. 7. Automated gates with attached electronic flow sensor. These are also avail- able commercially, but are expensive and complex. 1: Hydraulics of single and double baffle distribution modules used for field outlets. 2: New baffle distributors manufactured by ATEO Group, France. 3: Rubicon automated slip meter with both flow measurement and flow control. 4: Automated sluice gate to maintain a target flow. 120 | FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) Table 1: Considerations in the selection of medium-large canal flow measurement devices Magnetic, Automated Automated ultrasonic, Propeller gates that gates with Flumes CHO or or transit meter Distribution control attached Consideration and weirs metergate time pipeline (spool; not module water level electronic meter (spool; insert) on a flume flow not insert) or weir sensor Primarily used on pipeline supplies to outlet or pipeline N N Y Y N N N to pressurized system Requires a full pipe Y for immediately downstream of n/a Y Y n/a n/a n/a metergate the device With datalogger Provides reading of totalized and N Y Y N Y Y volume electronic level sensor Requires very accurate vertical Y N N N Y N N placement Requires sophisticated N N N N N Y Y electronics Magnetic If it uses meters have Requires a small battery sensor and n/a n/a n/a n/a n/a 6-12 yr. datalogger battery life Requires solar or AC power n/a n/a n/a n/a n/a Y Y and large battery backup FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) | 121 Magnetic, Automated Automated ultrasonic, Propeller gates that gates with Flumes CHO or or transit meter Distribution control attached Consideration and weirs metergate time pipeline (spool; not module water level electronic meter (spool; insert) on a flume flow not insert) or weir sensor Requires at least 30 cm drop in elevation and Y N N N Y Y Some good downstream ditch maintenance Target flow rate can be varied Y Y Y Y N Y Y at the outlet itself Applicable for drip and sprinkler irrigation w/o a N N Y Y N N N reservoir downstream of outlet Needs pre-screening to N N N Y N N N remove trash Can read/know flow rate directly from a single gauge Y N Y Y Y Y Y or dial Must purchase high quality One equipment not usually N manual Y Y Y Y Y manufactured locally gate 122 | FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Prices must include not only the device itself, but also the installation. Quite often an existing outlet must be completely replaced (including a road or canal bank crossing). The cost also depends upon whether the flow measurement device can be installed in the canal right-of-way or must be installed on a farmer’s property. The lowest prices are for CHOs, meter gates, distribution modules, and canal gate/flume combinations. The price per installed unit will range from $1,000 to $6,000, depending upon the complexities of the location. An excellent propeller meter or magnetic meter (both in a spool) for a 30 cm diameter pipe will cost about $3,500 plus installation. Automated gates, including both the gate and electronics, will cost from $6,000–$40,000 per unit, installed—depending upon the complexity. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Numerous books are available on the topic of flow measurement. The problem, as noted earlier, is to properly fit that knowl- edge into a solution for specific physical location. The links to technical documentation at the end of this section provide some references. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING The first step is to decide whether the outlet is intended to supply drip/sprinkler or only surface irrigation systems. Because of the complexities of some surface irrigation options, there should be an expert in irrigation flow measurement and control who is familiar with all the options and has successful practical experience. Such people are difficult to find, although there are many who have familiarity with a few devices. This is highly specialized, so the individuals who work on the design and specifications must be quali- fied, as opposed to contracting with a company that has had experience in the subject (but whose engineers with experience will perhaps not work on the job). It is highly recommended to visit other projects that have used the identical flow measurement technology that has been preliminar- ily selected. During that visit, issues such as training, maintenance, actual costs, acceptance by farmers, and problems experienced should be discussed in detail. FLOW MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) | 123 LINKS Practical literature on calibrated sluice gates, metergates, magnetic and other electronic pipeline flow measurements, CHOs, weirs, flumes, and so on is available at: www.itrc.org The USBR Water Measurement Manual is a widely used reference: https://www.waterboards.ca.gov/waterrights/water_issues/programs/measurement_regulation/docs/water_measurement/usbr_ water_measurement_manual.pdf The most widely employed software package for flume design is Winflume 2.0: https://www.ars.usda.gov/research/software/?modeCode=20-20-05-15 A comprehensive reference for the design of weirs and flumes with Winflume 2.0 is: Clemmens, A.J., T.L. Wahl, M.G. Bos, and J.A. Replogle. 2001. Water Measurement with Flumes and Weirs. Water Resources Publications, LLC. https://www.wrpllc.com/books/wmfw.html CANAL 124 | FLOW GATES MEASUREMENT AND CONTROL TO OUTLETS (IN CANALS) FICHE 3.3 Canal Gates DESCRIPTION OF THE INNOVATION Gates are devices to control the flow or level of water in canals. The most common “standard” irrigation canal gates include: 1. Sluice gates. This is the typical configuration in many countries. Sluice gates move vertically. 2. Radial gates. Radial gates have a curved upstream surface, and the frame piv- ots on a bearing located above the downstream water surface. Typical locally 1 fabricated radial gate that can be lifted above the lift mechanism and walkway. 2 3. Hinged, single sheet overshot gates. There are a variety of mechanisms used to move the gate up and down. Some are positive in both directions (e.g., the Rubicon gates or linear actuators); others such as seen below use the weight of the water to force the gate down. 4. Folding hinged overshot gates. The downstream end of the top hinged weir is moved vertically. These are primarily found in the United States and Canada. 1: Sluice gates. Manual. Bhakra, India. 2: Radial gate. 3: Bottom hinged overshot gate. Manual. Locally fabricated. Yuma Co. WUA, Arizona, USA. 4: Langemann gates. Folding hinge weir design. Automated. View from upstream. Western Canal Co. California, USA. 4 3 CANAL GATES | 125 Other canal gate configurations provide automatic water level 1 control via unique hydraulic designs that do not require electricity. The most common are: 1. Neyrtec hydraulic gates (or local variations of this brand), including a. AMIL gates for upstream water level control, and b. AVIO and AVIS for downstream control. 2. ITRC flap gate for upstream water level control – found primar- ily in California. These are constructed locally with free design software (http://www.itrc.org/reports/flapgate.htm). 1: AMIL gates. 2: AVIO gate. 3: ITRC flap gate. 2 3 126 | CANAL GATES Comparison Table Given the caveat that there are exceptions to every rule, the following table provides a comparison of various gate configurations. Some details are discussed in the sections after the table. (N = No; Y = Yes; M = In between) Gate configuration Characteristic Folding hinged Bottom-hinged AVIS or ITRC flap Sluice Radial AMIL overflow overflow AVIO gate Passes surface trash N N Y Y M M M Passes bed load Y Y N N Y Y Y Can be used for Upstream control Y Y Y Y N Only Only Can be used for Downstream Y Y Y Y Only N N control Always automated N N N N Y Y Y Always Always Always Can be automated for water level Y Y Y Y downstream upstream upstream control or flow control control control control Can be submerged on downstream (d/s) side if Y Y Y Y Y Y N automated for water level control Accurate rating for flow control if Y Y M** M** n/a n/a n/a submerged on d/s side External power required for 6 2 3 5 0 0 0 movement (0=none; 6=most) Often manufactured locally Y Y N Y N N Y M** – Accuracy depends upon the depth of downstream submergence; always requires excellent laboratory calibration because of complexity, so installation hydraulic conditions (especially entrance conditions) must match laboratory calibration conditions. CANAL GATES | 127 Discussion of Gates Features The following pertain in all cases to all these “standard” canal gates: 1. They have movable components so that an opening (for water to flow through) can be made larger or smaller, or a sill (for water to flow over) can be moved up or down. In some cases, they have both. 2. All can be used for either controlling flows (into the heads of canals) or controlling water levels (within the canals), although there are distinct hydraulic advantages/disadvantages of various designs for these functions. 3. The gate configuration should not be confused with the ability to automate the gate. Any standard gate can be operated manually, but any gate can also be properly automated with PLCs to provide water level or flow control if the proper canal automation expert is retained. If an existing gate is structurally sound and moves without restriction, it can be retrofitted into an automatic gate by using motors, actuators, and proper control logic. There is no need to purchase a new gate to replace a good existing gate, just because the new gate comes with an automation package. 4. There are numerous variations for each type of gates, which cannot be included in this short discussion. 5. Some overshot canal gates (e.g., Rubicon and Langemann brands) are sold almost exclusively with a PLC automation package. 6. Automated gates should always have a means of manually moving them without electricity in case of an electrical or motor failure. Gate Life Numerous options are usually available for new gate construction. Some factors that contribute to gate life include: 1. Thickness of metal: Thicker metal corrodes slow (percentagewise) and deforms less than thinner metal. 2. Corrosion: A qualified corrosion specialist should be hired to provide recommendations on corrosion prevention. All the fol- lowing are used in irrigation projects: a. Active cathodic protection that protects both the structural reinforcing steel and the gates and actuators. b. Sacrificial anodes located underwater or in moist soil or directly on the metal. This is like using anodes on boat hulls. c. Selection of the proper metal. While mild steel is common, there is increased usage of aluminum and stainless steel to fabricate gates. d. Coatings: There are wide range of metal coatings available—some of which must be applied at the factory and others can be applied in the field. They range from hot dip galvanizing to epoxy tar paint to anodizing. 128 | CANAL GATES 3. Seals: Some gates are designed to completely seal and stop all flow. Other gates, such as hydraulic gates (flap gates and Neyrtec gates) must move easily and therefore cannot have tight seals and will have some leakage when completely shut. There are numerous materials and designs for gate side and bottom seals. Power Requirements for Movement (Whether Human or Electric) 1. Some gates require 2 people just to move the gate manually. This does not create an environment in which gates will be moved frequently. 2. Gear actuators are available to provide a mechanical advantage for human or electrical movement. They are generally neces- sary if a gate is more than 1 meter wide. 3. Electric gear actuators are available with AC and DC electricity. In areas without a dependable electric grid, it is typical to use DC-powered actuators combined with a small solar array and battery storage. 4. Torque requirement: This is impacted by the gear actuators that are used. The hydraulic forces of radial gates are directed toward the pivot point (with a bearing) and there is very little side friction, whereas the hydraulic forces on sluice gates will push the gate against the frame and therefore there will be a large amount of friction. Bottom-hinged overshot gates must be lifted against the weight of the water. 5. Solar power is now common for many electric gate actuators—whether they are manually operated or automated. The use of solar power must consider: a. The size of the panel needed for the worst conditions of low sunlight—including the number of days without sun and the sunlight intensity. b. Vandalism: Solar panels can be stolen, broken, or shot. Some of these problems can be minimized by using tall pole sup- ports and special panels that can be shot yet still function. c. Cleaning of the panels several times per year: There must be a program for cleaning panels, with a means of reaching the panels. d. The power requirements for the gates and their actuators: Sluice gates, for example, can be the most power-intensive to move because the gate is pushed against the gate frame by the hydraulic forces of the water. e. Batteries: The size of the battery will depend upon the power requirement of the gate actuator, the frequency of gate movement, and the availability of sunlight. Batteries may need to be buried for temperature control and for minimization of vandalism problems. CANAL GATES | 129 Other Considerations 1. Floating trash collection: Overshot gates will pass most floating trash; sluice and radial gates will accumulate trash upstream. 2. Bed load movement: Undershot gates (radial and sluice) will pass bed load; overshot gates will not. 3. Upstream water level control under manual operation: Overshot gates (of the same width as undershot gates) will always provide better upstream water level control under manual operation. If the gates are automated there will be no difference— unless the power fails. 4. Gates for both flow control and flow measurement (rated gates): For manual operation, undershot (radial and sluice) gates can be rated—if they do not shift between what is known as a “submerged” and “free flow” (in which case a water jet is seen at the gate exit) conditions. Manually operated undershot gates also provide better consistency of flow rate than do overshot gates. If automated properly, there is no difference in consistency. Overshot gates are only recommended for flow control and measurement if they have free flow (the gate leave is higher than the downstream water level) and if they are automated. 5. All gates except sluice gates are typically installed so that no climbing of tall structures is need- 1 ed. Many sluice gates, except in the Americas, have extremely tall lift structures and operators need to climb up stairs with cumbersome wheels to make changes. The long gate shafts also need special intermediate bearings to prevent them from twisting when they are being closed. Features that Can Be Included to Improve Operations Radial Gates Improvements that can be made include the following: 2 1. Connect the lifting cables to the front bottom of the gate, rather than to the top of the gate. This allows the tops of the gates to be lifted much higher than the gate gears and actuators. 3 2. Use cable spools with grooves to improve the uniformity of gate movement and increase the life of the cables. 1: Sluice gates with a tall support structure and difficult access. Baco Bucayao, Philippines. 2: Automated small radial gate with wheel for manual operation. 3: Radial gate cable spool with grooves to neatly coil the steel wire rope. 130 | CANAL GATES 3. Install the pivot point above the highest downstream water level. This will not usually match standard pre-designed gate templates, and it does somewhat increase the lift force require- ment. But this keeps the bearings dry and more easily serviceable. Sluice Gates Options for improving sluice gates include: 1 1. Use more, smaller gates in parallel. This reduces the required vertical openings, which enables the design of low-profile sluice gates. It also improves the ability to make repairs. 2. Offset the lifting vertical screw shaft about 500–750 mm from the gate leaf. In addition, attach the lifting shaft closer to the bottom of the gate leaf. Because this places the gate Gate can rise above gear operator because gear boxes behind the gate, they do not interfere with the vertical gate movement. The gate of offset shaft leaves can be lifted above the gate gear boxes/assemblies. 3. In deep channels, use bulkheads above and behind the sluice gates, so the sluice gates Sluice may only need to be 2 m high, for example, rather than 4 m high. This also allows the lifting gate 7.5’ opening mechanism to be placed close to the ground surface. Offset shaft Automated Hydraulic Gates 2 These gates operate without electricity. Rather, they open and close appropri- 3 ately (if they are designed, installed, and balanced properly) based upon a design balance of couples (rotating moments). The uplift force of the water is counter- balanced by the downward force due to the weight of the steel. They all have a good bearing assembly so that the rotation occurs easily. The Neyrtec gates (e.g., AVIO, AMIL, AVIS) have been used for decades, and still provide a simple solution for water level control that is acceptable in many situations. The biggest factors against their usage are: (i) people copy them, but copy them incorrectly, so they do not work properly; (ii) they usually require new construction because their cross sections must have specific trapezoidal dimensions—therefore they are not always easy to use as the replacement for an existing gate; (iii) they are an expensive option; and (iv) they are often balanced 1: Parallel radial gates with the pivot points (on left hand incorrectly by properly adjusting the counterweights. side) above the downstream water level. 2: Side view of a sluice gate with an offset shaft. 3: AVIO gates. CANAL GATES | 131 The ITRC Flap Gate is modeled after the old (1940’s) Begemann gate from the Netherlands. Because no design criteria could be found for the Begemann gate, ITRC developed its own design model and revised the design over a period of 20 years. The software for design is available for free download at http://www.itrc.org/reports/flapgate.htm. There are hundreds of these in the western USA, constructed and installed by the irrigation districts (they are not commercially available). They are limited in use because they need about 75–100 cm of drop across the structure, and the water depth on the upstream face of the plate should not be greater than about 75 cm or else the counterweight becomes too heavy. WHAT BENEFITS CAN THIS INNOVATION BRING? By knowing options for gate selection, designers can often reduce costs, improve control, and make operation simpler for operators. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Good gate manufacturers (e.g., Fresno Valves & Castings, Waterman, and Hydro Gate) will provide their own recommendations for materials, coatings, actuators, etc. They are accustomed to responding to government requests for bid, with detailed specifications that are particular to each project. An examination of the specifications from several good gate manufacturers can provide a start to a conversation about what is needed for any installation/project. Various government organizations have developed very simple, or very detailed specifications. The problem is that general specifications do not define the details that are needed for a particular situation. For example, a specification may only provide a list of possible metals that can be used, such as “Stainless steel must be A 167, A 276, or A 582; Type 302, 303, 304, or 304L”. An example of a specification is: US Dept. of Agriculture. Natural Resource Conservation Service. 2013. MATERIAL SPECIFICATION 573 – RADIAL GATES. MT-573-1. There have also been various studies of gate failures. These can be informative and helpful in avoiding similar problems. An ex- ample is: https://www.usbr.gov/ssle/damsafety/risk/BestPractices/Chapters/G1-FailureOfRadial-Tainter-GatesUnderNormalOperationa lConditions.pdf SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING AND SERVICING Standard, historical, off-the-shelf designs should be re-examined considering new materials and options. 132 | CANAL GATES OTHER IMAGES 1 2 3 4 5 6 1: Radial gate. Colorado River Indian Tribes. Arizona, USA. 2: Motorized, manually operated radial gates. 3: Manual sluice gates with concrete bulkhead. View from downstream. 4: Rubicon gates. Automated hinged overshot. RD108. California, USA. 5: AVIS gate. Downstream level control gate. Main canal Doukkala project. Morocco. 6: AMIL gate. Automated upstream control. Tafilalet, Morocco. 7: Early ITRC Flap gate with pillow block bearings, locally manufactured. Turlock ID, California 3 CMS. USA. 8: ITRC Flap gate inserted into vertical slots; replaces upstream radial gate. Low flow 7 8 condition. Glenn-Colusa ID, California, USA. CANAL GATES | 133 FICHE 3.4 Canal Regulating Reservoirs DESCRIPTION OF THE INNOVATION Classical Regulating Reservoirs Except for a relatively few canals under downstream control, most irrigation canals in developing and developed countries are de- signed with upstream control. Under this method of control, the flow rate into the head of a canal system is set to the anticipated demand downstream. If the flow rate into the head of the canal is too high, there is operational spill at the tail end (most downstream end) of the canal. If the flow rate into the canal is lower than the demands, there is a deficit at the tail end. This phenomenon is often called “feast or famine” at the tail end. The causes of feast or famine are many, and include the following: 1. As more drip or micro systems are used, and as other field ir- rigation practices are improved, there is a demand by farmers for more flexibility of water delivery. This flexibility makes it more difficult for canal operators to match the canal flow rates A regulating reservoir. Turlock Irrigation District, California, USA. precisely to the demand. 2. A flow rate change made almost instantaneously at the head of a canal will arrive at a point several miles downstream after a considerable amount of time (hours or days). Moreover, the flow rate change arrives gradually. It may take an hour (or more, in a large canal) for a complete flow change to stabilize at a downstream point in a canal after the change begins to arrive. 3. Flow rate measurement is imprecise. In the field, ±6% accuracy is considered very good in many projects. 4. There are numerous reasons that turnout (outlet gate) flows will change unexpectedly, including fluctuations in the supply canal water level or fluctuations in the delivery pressure or water level (downstream of the outlet) and unauthorized operation of outlets (turnouts) by farmers. 134 | CANAL REGULATING RESERVOIRS Without regulating reservoirs, feast or famine typically is handled in one of three ways, none of which is satisfactory: 1. It just exists. Farmers at the tail ends of canals receive the worst water delivery service in the project. 2. The irrigation operators always deliver more water than is needed. Therefore, spill occurs all the time. This is a convenient way to provide excellent flexibility to users in a very simple manner, but it in- creases river diversions, and the spill may not be re-used efficiently. 3. Spill is minimized by using canal pool storage for the excesses or deficits. This topic is discussed later. Regulating reservoirs, with a classic location of two-thirds of the distance Canal with automatic gate to re-establish flow control. Excess down a canal, offer the following advantages: flow rate enters into regulating reservoir on the right via a long crested weir. Fresno irrigation district, California, USA. 1. They greatly reduce canal spillage. 2. The canal operation becomes much simpler. The water master or main operator of that canal determines the change in water orders and looks at the water level in the reservoir. If the reservoir is too high and moving upward, a flow rate change that is slightly less than the change in water orders is made at the head of the canal. 3. Reservoirs allow for flexibility of water delivery upstream of the reservoir, while the canal pool water levels upstream can re- main fairly constant with good upstream water level control. All the fluctuations in flow rate show up at the regulating reservoir. 4. The last sections of canal (those downstream of the reservoir) no longer absorb the fluctuations that originated in the upper two-thirds of the canal. Those flow rate fluctuations (pluses and minuses) are absorbed by the regulating reservoir(s). 5. Reservoirs allow for more flexibility of water delivery downstream, in one of two ways: a. The canal downstream of the regulating reservoir is operated on downstream control or is converted to closed pipelines. The flow rate entering the project area downstream of the reservoir will automatically match the actual user demands precisely. b. The canal downstream of the regulating reservoir is operated using upstream control. Because the total length of the downstream canal sections is only about one-third to one-quarter of the full system length, operators can respond quickly to downstream flow demands. The reservoir provides an extremely flexible supply, so the operators do not need to provide anyone with advance notice before increasing or decreasing the flow into the downstream canal section. CANAL REGULATING RESERVOIRS | 135 Buffer (regulating) reservoirs are often constructed throughout irrigation projects, From river Main canal without reservoir in each of the hydraulic layers. Note in the figure on the right that the buffer reservoir cannot be at the very end of the canal because there must be sufficient irrigated area downstream to receive the volume fluctuations that are temporarily stored From river Main canal with reservoir Very little in the reservoir. In the figure, the curved fluctuation downstream arrows indicate uncontrolled and fluctuating with reservoir flow rates. Straight arrows indicate known and well controlled flow rates. A common argument against regulating Legend: Upstream water level control Flow control and measurement reservoirs is that they remove land from production and the cost of land acquisition A main canal control configuration with and without a buffer reservoir. is too high. But those arguments are short- sighted. They ignore the fact that in many projects there are already substantial areas with no or low production (and therefore of very low value) because of inefficiencies and waterlogged soils that could be remedied with better canal control—which requires re-regulation at some point in most projects. The reservoir does not need to be immediately adjacent to the canal—there can be a connection of a kilometer or more between the reservoir and the canal if land is not available adjacent to the canal. Furthermore, it is well known that farmers sell land for urbanization. Selling land for reservoirs is no different. Three other issues should be addressed up-front: 1. Silt/sand in water that enters the reservoir will settle out. That means the reservoir must be cleaned out occasionally; it must be designed appropriately (often in cells) and access (such as side ramps) must be provided. There must also be a place to dispose of the silt. The positive aspect is that because the only flow into the reservoir will be the discrepancy between supply and demand, most of the silt will remain in the canal flow. 2. Seepage must be considered. Refer to Fiche 3.9: On-Farm Water Reservoirs for information on seepage reduction. 3. In most (but not all) cases, pumps are needed to move water in and/or out of a reservoir. But the pumping requirement is a small fraction of what is often needed for on-farm wells that are used by farmers to obtain good water delivery service. Not only is the flow rate a fraction of the total canal flow rate, but the lift is also usually small. 136 | CANAL REGULATING RESERVOIRS 1: Government Highline Canal discharging excess flows into Highline Lake. This location was modified by adding pumps to return flows, as needed, to the canal. The canal was re-started at this point. Colorado, USA. 2: New pumping plant for the 1 2 Highline Lake return. Daytime-Only Irrigation by Farmers This has been identified as a major problem in Egypt and has been discussed in many forums. One solution is to use many farm (mesqa-level) reservoirs, as noted in the on-farm fiches. Another solution is to use fewer and larger canal reservoirs to capture the water during the night. The reservoirs must be larger than those intended to re-regulate the smaller typical fluctuations that occur throughout continuous irrigation projects. Special Regulating Reservoirs Two special situations do not correspond to the descriptions above of upstream controlled canals. They both pertain to the avail- ability and cost of electricity for pumping. 1. “Cascading irrigation systems”. Some projects have a series of pumping stations that lift water to canals that run along the contour. This was common in many old Soviet irrigation projects. There are often serious problems with the dependability of electric power, and the pumps may shut down unexpectedly for many hours—sometimes on a daily basis. During those hours, the canals drain. Good water level and flow control in the canal systems disappear as the canals drain, plus throughout the hours needed to bring the whole system back “on line” once power is restored. Harmony with water users is lost because their subsystems become uncontrollable. For these situations, the solution is to place a buffer reservoir slightly above the current discharge of each pumping plant’s pipelines. The reservoirs need to be filled with a portion of the flow when the electricity is available. They must be able to supply the contour canals by gravity when the electricity fails. 2. Peak electric load management. There are variations of this that have been utilized in California to solve problems with insuf- ficient power availability on the electric grid during certain hours. Two different examples are: CANAL REGULATING RESERVOIRS | 137 a. On the Kaweah River, higher-than-typical flow rates are released from a dam on the river during peak electric demand peri- ods. Those high flows are routed down the river and into a large regulating reservoir in Tulare Irrigation District, for release at a constant flow rate into the district. This addresses peak power production. b. The Berrenda Mesa Water Storage District lifts water into a high regulating reservoir at the head of its main canal during times of low power rates (“off-peak”). The regulating reservoir was expanded to accomplish this, so that canal flows can respond to downstream demands rather than upstream restrictions. This addresses peak power consumption. Using In-Canal Storage for Regulation Storage This subject frequently arises. Although there are a few cases where it is feasible, in general it is not recommended because of the following points: 1. The available storage is typically much less than people imagine. 2. A major component of improved upstream control of canals is the maintenance of a constant water level in the canals. The reasons include: a. Control can be very simple, with long-crested weirs. b. Canal lining does not “float” if water levels remain fairly constant. c. High water levels are needed just to service many outlets (turnouts) d. Steady canal levels provide steady flow rates to customers (outlets and at canal bifurcation points) e. Rodent damage to canal banks is minimized with constant water levels. f. When flow changes are made at the head, the time to transmit the changes to a point in the system depends on how much the canal pools need to fill/empty. Constant water levels in canal pools minimize this transmission time. 3. Proper real-time management of numerous structures with a program of fluctuating canal water levels can be extremely complex and is likely to suffer from poor operation. WHAT BENEFITS CAN THIS INNOVATION BRING? It is impossible to easily manage an upstream controlled canal to provide flexibility to customers and simultaneously have a high conveyance efficiency unless there are buffer reservoirs. The benefits of providing high quality water delivery service, and having efficient irrigation projects, have been explained elsewhere. 138 | CANAL REGULATING RESERVOIRS Upstream control is the most simple, safe and robust means of distributing water throughout an irrigation project. While other canal control technologies exist, they are often incompatible with existing situations and always involve complexity and higher risk. Buffer reservoirs are a physical infrastructure alternative to complexity and risk. There are also substantial benefits for some electric powered pumping stations, as noted above. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? It is rare that buffer reservoirs cannot be integrated into projects. It is primarily a matter of whether designers and management un- derstand the constraints of irrigation project water operations and the concept of water delivery service. If they do not understand these two subjects, there will be over-riding arguments regarding the costs and availability of land, and the cost for pumping. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS There are numerous details regarding regulating reservoirs, related to: 1. Proper sizing of the reservoir volume, which depends on both hydraulic and land availability variables 2. Proper sizing of the inlet and outlet flow capacities 3. Control of flows into the reservoir 4. Control of flows out of the reservoir 5. Specific hardware used for in/out 6. Control into the canal or pipelines downstream of the reservoir 7. Emergency considerations 8. Seepage, protection from vandalism, and other issues “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Remote monitoring of water levels in the reservoir is typical. Depending upon the complexity of the controls in and out of the reservoir, programmable logic controllers may be needed to automate gates and pumps—in which case more complex SCADA (su- pervisory control and data acquisition) is commonly used. Downstream control or pipelines are often used downstream of regulating reservoirs—both of which require special design and management. CANAL REGULATING RESERVOIRS | 139 PRACTICAL EXAMPLES Regulating reservoirs have been used for many decades. Early applications were at the transition point between upstream control and downstream control—such as in the Doukkala Project (Morocco) and Lake Woollomes in the Friant-Kern Canal (California). Although not specifically in the category described in this fiche, many large canal systems that have been described as “automated” and “state of the art” do indeed have regulating reservoirs somewhere in the system that make the operation considerably easier. These include the Canal de Provence (France), the canal for the Central Arizona Project, the California Aqueduct, and the Colorado River Aqueduct. A characteristic feature of the configuration of irrigation systems in Central and Southern China is the number of large, medium and small reservoirs, which forms an integral part of the systems. Large reservoirs created by construction of large dams are connected to medium reservoirs and to hundreds of thousands of village reservoirs and ponds. For example, the Pi-Shi-hang Irrigation Districts, which serve 680,000 hectares in Henan Province, consist in a network of canals con- nected to five large reservoirs, 24 medium-sized reservoirs with a total active capacity 1 of 420 million m3, 113 small reservoirs with an active capacity of 205 million m3 and 210,000 storage ponds. The reliability and flexibility of water delivery of these systems is very high. There are cases where regulating reservoirs are already found in ideal locations to re-start canal regulation but are instead used only as storage reservoirs. An example is the Chotiari Reservoir in Sindh, Pakistan. Western US irrigation districts have typically included reservoirs as part of their modernization plans and investments over the last 20 years. Some of these districts have used regulating reservoirs for many decades and are now 2 expanding their numbers and improving the management of the existing reservoirs. An example of a new reservoir is seen in the figure on the bottom Flow control here for 2 canals, where they are restarted right. It is located approximately 170 km downstream from the water source, and is at the point where two canals can be re-started with target flow rates. Water arrives via 1: Long crested weir inlet to a regulating reservoir. Chowchilla upstream control, from source 170 km away WD, California, USA. 2: A typical regulating reservoir that enables Regulating reservoir operators to re-start shorter canals with known flow rates, with Automated pumps and gates move water into and out of the reservoir complete flexibility. Henry Miller RD, California, USA. to maintain a constant canal level AUTOMATION 140 | | CANAL WITH RESERVOIRS REGULATING PROGRAMMABLE LOGIC CONTROLLERS (PLC) FICHE 3.5 Automation with Programmable Logic Controllers (PLC) DESCRIPTION OF THE INNOVATION In the context of off-farm irrigation, automation is the control of pump or gate movements to maintain a target value (for example, pressure, water level, or flow rate) without any human intervention. For many decades, there have been excellent automatic gates that do not require electricity or electronics; instead, they rely on a balance of hydraulic couples (a balance between the weight of the gate and hydraulic forces) to control an upstream or downstream water level. There is ample literature to describe those hydraulic gates. This fiche focuses on programmable logic controllers (PLCs) for the control of gates and pumps; they have become standard in many irrigation projects. PLCs are often used to collect electronic signals, process them in a computer to decide if a gate position, or the speed or status of a pump, should be changed, and then activate control signals to accomplish any required change. PLC automation always involves a feedback loop. Once an action is performed, the cycle is repeated and changes continue to be made until the actual control value (for example, water level) is reasonably close to the target value. The figure on the left barely scratches Controlled value is measured Analog signals (pulse, the surface of the complexity of PLC Digital signal is used by and an electronic (analog) voltage, amps) are on-site PLC for computations, automation. All components must function signal is generated and sent converted to numerical or is sent to remote computer to an analog/digital (A/D) (digital) value. On-site PLC properly and without failure all the time for computations. signal converter. stores values, organizes for automation to be successful. Proper communications, etc. functioning is a corollary of accuracy: for example, if a water depth is properly mea- Other control-related values Values are used for computations in a control sured, then the measurement signal has (e.g., pump speed, pump on-o status, gate Local PLC sends signals to algorithm (set of formulas) to been properly calibrated and the resulting determine if the controlled position(s), other water open/close relays value faithfully represents the physical levels) are measured and CYCLE IS (switches) to activate value equals its target value, electronic (analog) signals REPEATED gates/pumps and if/how much quantity. Accuracy and instrumentation are generated and sent to appropriately if a change movement/change is needed are discussed in more detail in Fiche 3.6: A/D signal converters. is needed. by gates/pumps. SCADA. This fiche focuses on the two orange colored boxes in the figure. AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) | 141 PLC automation is used to control canal gates and pumps for the following reasons: 1. For some types of control (for example, downstream control of canals), the computations are usually too complex to be done manually. 2. The control time step (the interval between potential changes in pump speed, in pump on/off sequencing, or in gate position) can be very short, allowing more precise control than could be achieved by humans. Typical control time steps range from 30 seconds to 15 minutes. 3. The control process is always the same and is well defined. The quality of control does not depend upon the operator. 4. People (operators) do not need to be on-site to make gate movements. 5. Often a project already has excellent gates in place with motors and gear operators, but they are manually operated. It can be relatively inexpensive to automate such installations, as opposed to purchasing and installing new gates. 6. For a variety of reasons, managers tend to want a PLC-automated system even if simpler and more robust options exist. Key points regarding canal automation with PLCs include the following: 1. Many PLCs have old electromechanical logic programmed into them. These are all “hunt Incoming Power Source and peck” (trial-and-error) systems, designed by clever mechanically-inclined individuals before PLCs and electronic sensors were available—such as the old “Littleman” controller Lower Lower Timer in the western United States. Modern control systems can provide much better control, but T for most field personnel the logic is not easy to understand or program. That said, there T is no more reason for field personnel to understand the programming than there is for an Anti-Hunt Raise Timer average person to understand the internal workings of a laptop computer. Raise Reversing Starter 2. Early canal automation (and much of what exists today) took account only of an individual Counter Weight gate or pump and the water level immediately upstream or downstream of it—just as auto- matic hydraulic gates (ITRC Flap Gate, AMIL, AVIS) do. Since the early 2000s, it has been Float 30 Meters generally understood that proper control logic must consider the deviation (error) of the variable being controlled (for example, water level) from its target value, the mechanics of the gate/pump itself, plus the characteristics of the canal pools. The latter is often ignored or incorrectly considered—with resultant instability of control and the formation of large waves and excess gate/pump movements. Schematic of old electromechanical “Littleman” controller. 142 | AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) 3. Canal automation procedures that work successfully on canals with very few flow changes and little flexibility may not be suc- cessful once the canal is operated with more flexibility, and with more frequent or greater flow rate changes. 4. It is relatively simple to automate up to three check structures in series for upstream control to obtain reasonably quick, stable control. “Hunt and peck” automation logic typically fails with more check structures (cross regulators) in series if there are frequent and significant flow changes. 5. It is relatively simple to automate a check structure to deliver a target flow rate into the head of canal. If there is a good means of measuring the flow rate, almost any logic can be used successfully. However, improved logic will achieve the target flow rate more quickly, and with fewer gate move- ments, than cruder alternatives. 6. All downstream water-level control schemes need to be properly simulat- ed in specialized, unsteady flow canal simulation models capable of using simulation time steps of one second. Most upstream controlled algorithms also require this simulation to properly tune the control constants. 7. In general, the organization that decides on the appropriate control logic (such as upstream control, immediate downstream, or far downstream) Typical headgates into a canal that are automated to should also conduct the canal simulations, tune their control algorithms maintain a target water level over a flume. Note that the using the unsteady flow canal simulation models, write the complete con- algae growing on flume will create an inaccurate reading. trol code that goes into the PLCs, download the control code (which must also interface with all the sensors and communications) into the PLCs, check calibration of sensors, and “field-commission” the installation to ensure that it functions properly. In many irrigation projects, however, these steps are carried out as discrete steps by different companies or individuals—which almost always guarantees poor results. 8. Two fundamentally different approaches to PLC-based control for canal automation are currently prevalent: a. Strategy 1: The farmers have the flexibility to operate their own outlets (either automatically or manually) for the flow rate that they select. The system is responsible for automatically responding to those flow rate changes. The exact amount of flexibility (such as whether farmers must request a flow rate in advance, and how far in advance) will depend upon the investment level, topography, and other factors. Project control is customized based on existing hardware and new invest- ments. Regulating reservoirs are commonly used to buffer flow changes, as opposed to attempting to match canal flows exactly to offtake flows. AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) | 143 b. Strategy 2: A central office remotely and automatically controls all the gates and outlets (delivery points), based on ad- vance knowledge of all outlet flow rates and delivery durations. This control system promises (but often does not deliver) no spills at the tail ends of canals. This was developed for canals that supply large, surface-irrigated fields that can be suit- ably irrigated with preprogrammed, fixed-flow rates. The advance notice required from farmers for them to obtain an outlet delivery will depend on the system, and the location within the system. 9. The two different approaches have the following differences in hardware and logic: a. Strategy 1: All PLC control is distributed control: that is, all the computations are done within local (on-site) and independent PLCs at each control structure. Thus, all computations are done on-site, even though the PLCs are linked to the office for remote monitoring, remote changing of target values (such as flow rates into canals), and remote upgrading of the software. Furthermore, this strategy is not tied to a single brand or type of hardware. Proper control logic can be used to automate pumps, overflow gates, underflow gates, compound gates, and other devices. There are two associated philosophies: i. Upstream control is the simplest and most robust control method available for most canals—if regulating reservoirs are utilized. The check structures can be automated with PLCs for upstream control (often the best solution if motorized gates already exist), or long-crested weirs can be used. Automation of the inflow into, or the outflow from, reservoirs is often done using PLCs to control gates and/or pumps. Therefore, most of a project will operate under upstream con- trol (often with long-crested weirs as well as PLC-based automated gates, depending on the location), with regulating reservoirs at or near the downstream ends of upstream-controlled sections. ii. Downstream control can be useful to operate “on demand” to supply downstream flow-rate requirements—but it must be used with caution, and is typically only used at the very downstream end of canal systems (downstream of regulating reservoirs). Downstream control is recognized as a high risk because if one structure fails, the automation control for all downstream gates will no longer function properly. Downstream control should be designed for distributed control, as is upstream control. Flow rates at outlets are not part of the computations. Pipelines are often used at the far downstream ends of upstream-controlled canals (instead of using canals with downstream control) because of their ease of manage- ment and lack of spills. b. Strategy 2: The canal system is automated via remote, centralized control. All outlet flows must be constantly measured and remotely monitored and controlled. In other words, farmers and field operators do not manually operate outlets. Good control of water levels and no spill are achieved by proper advance scheduling of all outlets flows from the central office, and by moving the gates properly, sometimes with some local independent gate adjustments based on water levels. As with downstream control, this is relatively high risk because if one control structure fails to operate properly, none of the other downstream gates can be effective. This is a very sensor- and communications-dependent strategy that requires 144 | AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) a sophisticated, mobile, well-trained, well-funded, and stable technical backup staff. It is usually sold as a package with a specific brand of equipment that replaces existing canal gates. WHAT BENEFITS CAN THIS INNOVATION BRING? As noted earlier, PLC automation (if successfully implemented and sustained) can often bring much better control and water delivery service than the existing system can provide. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? PLC automation should be attempted only if there is long-term funding, well-trained staff, meticulous attention to detail and neat- ness, staff who will be on-site for decades, and if the right questions are asked and answered (see “the Special Considerations” section below). TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS There are many specifications for individual components. However, even if the best equipment is used, there tend to be failures of components. The project managers must be aware of this and have the budget and personnel available to immediately resolve the problems. There should always be a detailed SCADA/telemetry and automation plan in hand before work begins. While component specifications or standards are important, they only obliquely address the fact that automation packages are systems. It is essential that the expected performance be defined by the customer in substantial detail, and that performance be guaranteed by the provider. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING This is truly an investment where the buyer must beware—or at least exercise an abundance of caution. Canal automation is a very specialized subfield of construction and operation. Even companies that are accustomed to the automation of manufacturing plants and chemical processes will rarely, if ever, have the experience required to successfully automate canal systems. Successful auto- mation projects are not usually installed by the same general contractors who install gates, canal lining, and other elements. Before entering into any canal automation contract, the following questions should be answered in writing: AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) | 145 1. Which of the following are available from another vendor and can be seamlessly substituted for the original equipment and fitted into the equipment shelter or the panel boxes of the equipment that you are considering? a. Water level sensors b. Radios c. PLC d. Gate position sensors 2. What is the quality of control that is promised? a. Do the outlet (turnout) flow-rate changes need to be preprogrammed into the controller? b. Do the outlet (turnout) flow rates need to be remotely monitored in real time for the control to work properly? c. Does the control still work if there are unannounced outlet (turnout) flow changes? d. Does the control still work if there are unannounced drainage inflows? e. At low canal flow rates, what magnitude (CFS) of instantaneous and unannounced flow rate change can be made at every turnout in every canal—yet create no negative impact on canal lining, no spill at the tail end or intermediate spill points, and no negative impact on other users in the same canal? f. At low canal flow rates, what is the maximum unannounced combined turnout flow rate change (CFS—defined for each canal) that can be made with no negative impact on canal lining, no spill at the tail end or intermediate spill points, and no negative impact on other users of the same canal? g. At high canal flow rates, what magnitude of instantaneous unannounced flow rate change can be made at every turnout, in every canal? h. At high canal flow rates, what is the maximum allowable unannounced combined turnout flow rate change (as defined above)? i. How long will oscillations persist after a significant unannounced flow rate change near the end of a canal? j. With a 5 percent unannounced flow rate increase near the end of a canal, during a condition of low canal flow, what will be: i. The maximum increase or decrease in water level in each pool? ii. The number of movements of each gate before oscillations stop? k. What is the answer to the preceding question when there is a high canal flow rate? 146 | AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) l. If a single gate malfunctions in the middle of a canal, how will that impact the level of service provided to the turnouts in the canal? 3. Are there redundant sensors on all the control sensors (water level, gate position)? (Note: It is recommended that redundant sensors always be required for automated control. Sensor outputs will drift and fail.) 4. If there is redundancy, how does the programming handle the case of a. A difference in reading? b. A zero measurement? 5. Has the vendor provided excellent simulated control for each pool in each canal, for the conditions listed above? The figure below illustrates results of a typical simulation run for a single pool (Source: ITRC). 6.5 260 Water Depths at U/S and Far D/S of the Check and Gate Opening (Ft) 6.0 240 5.5 220 5.0 200 Total Downstream Turnout Flow (CFS) 4.5 180 4.0 160 3.5 140 3.0 120 2.5 100 2.0 80 1.5 60 1.0 40 0.5 20 0.0 0 0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 Time (hour) Water level @ 95% DS of pool (Ft) Vertical gate opening (Ft) KP = - 12 Top of canal lining @ far end (Ft) Weir crest @ far end (Ft) KI = - 0.15 Target depth (Ft) Water level @ far end of d/s pool (Ft) FC = 0 Total downstream TO flow (CFS) 6. How much fine tuning will be needed by the contractor before everything works properly on a single lateral canal? a. What is the timeline from initial commissioning to final good control (explain the calendar time and number of trips needed)? b. Is this something that can be completed by the vendor alone, and if not, what assistance is needed from district employees? c. If the automation does not work as advertised, can the system be run manually? i. How will that be done? AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) | 147 7. What signals or data must go to a central location for processing if the control is to function as promised? a. What will be the result if a few of the communications links fail? b. What will be the result if there is a complete communications failure? 8. What is the probability of any aspect, component, or link of the communications system failing per year? (For example, if a single radio fails, that is one component). 9. If the system does not perform as specified/contracted, and by the date agreed, what is the penalty? a. How much money will be withheld from the final payment? b. Who determines whether or not performance meets contractual obligations? 10. Describe annual, long-term maintenance. a. What is the expected life of i. The solar system? ii. Water-level sensors? iii. Gate-position sensors? iv. Gate-movement actuator? v. The PLC? vi. The radio? b. What is the annual cost of maintenance in terms of i. Parts? ii. Labor plus travel? c. What license, maintenance, or other fees are required? (Quantify them) d. What are the details of the warranty? i. Who decides who must pay for a solution? The district/project or the vendor? ii. What is the promised maximum time that can elapse between notification of a problem (regardless of the day or hour) and its resolution? iii. Is there a deductible? 148 | AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) iv. When does the warranty period begin: (1) Immediately after installation? (2) Or after everything has been fine-tuned? v. Does the warranty include (1) All labor and travel expenses? (2) All parts, with no deduction for age? vi. How long is the warranty? 11. Expectations by the vendor (contractor) during installation: a. What does the vendor expect from the district/project: i. Equipment access? ii. Notification of growers? iii. Physical assistance by staff? iv. Obtaining all permits? b. How long will water need to be shut off for each gate that is installed? Is that guaranteed? Is there a penalty clause if it takes longer? 12. What are the details of training? a. Have the training manuals been shown to the customer? b. When will the training occur? c. What are the qualifications necessary for a district/project person to perform various activities? d. How long will the training last? 13. What documentation will be provided? a. Training manual b. Maintenance manual c. Manual of all parts/components d. Tag lists for all SCADA and HMI variables AUTOMATION WITH PROGRAMMABLE LOGIC CONTROLLERS (PLC) | 149 e. Wiring diagrams f. Other material “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY n SCADA/telemetry n Flow measurement n Improved procedures for water ordering and accounting and billing. SUPERVISORY 150 | | AUTOMATION WITH CONTROL PROGRAMMABLE AND DATA ACQUISITION SYSTEM (SCADA) LOGIC CONTROLLERS (PLC) FICHE 3.6 Supervisory Control and Data Acquisition System (SCADA) DESCRIPTION OF THE INNOVATION SCADA is an acronym for Supervisory Control and Data Acquisition. It is sometimes referred to as “telemetry.” SCADA systems have proven to be one of many valu- able tools available to irrigation systems that are in the process of being modernized. The term “SCADA” covers a multitude of functions and options. Systems range from very simple remote monitoring using cell phone technol- ogy and web-based private company data portals to complex monitoring and integration into control systems that have independent radio networks and sophisticated office systems. There are also large variations in the scope and com- plexity of SCADA projects. For example, using SCADA for remote monitoring of a few distant canal spills is a very different scenario from its use in the comprehensive automation of all check and lateral structures along a main canal. Table 1 below provides a summary overview of SCADA options, ranging from the simplest to the most complex. As complexity increases, so do expense and technical challenges. In this discussion, the term SCADA does not refer to any particular automation or control logic. Rather, it refers generically to the sensors, actuators, and equipment and processes associated with the collection, transmission, and display of data or information. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 151 Table 1: SCADA (telemetry) options Applicable communications Frequency of data Case Basic function Standard Satellite transmission Satellite Radio or Satellite or cell (e.g. cell phone microwave internet phone GOES) Alarm for high/low conditions Only if alarm condition 1 X X X X X without knowing the values. exists. Alarm for specific values, Only if alarm condition 2 such as height, position, X X X X X exists. temperature, pump speed. Remote monitoring of specific For river basins—often values, such as height, a few times per day. For 3 X X X X X position, temperature, pump irrigation system canals— speed. No alarming. often once per minute. Once per day. Remote Cases (2) + (3) (monitor + monitoring can be 4 X X X X X alarm). overridden by an alarm exception at any time. Case (4) plus remote manual Once per 30-60 sec. Slow control of a pump on/off, 5 times are cumbersome for X X a pump speed, or a gate operators. position. Case (5) plus (a) remote changing of target values 6 and (b) local independent Once per minute. X X automation, Referred to as “distributed control.” Case (4) plus centralized Once per minute; once 7 computation of gate/pump X X per 15 minutes. movements. 152 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) SCADA systems involve technical terms and acronyms that can make a discussion difficult to follow for newcomers. Hence the fol- lowing list. Acronyms HMI human–machine interface. The software and hardware at the base station (office) that allow operators to view remote data, change target (desired) controlled variables such as flow rate or water level, and store and retrieve information. PLC programmable logic controller. Typically, specialized, rugged (hardened) computers located in the field. The computer itself is able to process some information—the extent depends on the control strategy. These units have connection ports for n Sensor wires such as water-level or gate-position sensors; n Relays (devices that act as switches to turn motors on and off); n Communications, either send or receive, or both send and receive; n Power supply to power the sensors and the computer; and n Operator interface terminal (OIT)—see below. mA milliamp. A measure of the electrical current that flows through a sensor, and which corresponds to the measured engi- neering value, such as water depth or position. OIT operator interface terminal. A minicomputer linked to the PLC with a screen (often a touchscreen) for use by the operator. When operators arrive on-site, they can select various buttons to change target depths or flows, or to see the values of various sensors. If the communications link to the office has been broken, this provides an on-site alternative to changing some variables in the PLC. RTU remote terminal unit. Sometimes used interchangeably with “PLC,” it can include additional components, such as batteries, the radio, the equipment to control battery power, and terminal blocks (devices used to connect various wires from the field to the PLC). SCADA Supervisory Control and Data Acquisition. As mentioned above, this general term is used here to encompass the collec- tion of sensor data, transmission of data and instructions, and archiving or organization of information. There are hundreds of variations of SCADA systems in terms of hardware and functions. UL Underwriters Laboratory (provides global safety certification). SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 153 Modernization Plans SCADA systems, by themselves, do not improve the operation of irrigation systems. They are tools that, if designed, installed, and maintained properly, can be very useful for irrigation system operation. But modernization does not start with SCADA. By contrast, SCADA fits within a larger plan. Ideally, a suite of immediate and long-term objectives—and associated systems—would be defined and prioritized within a comprehensive “Modernization Plan” resulting from an in-depth system appraisal, with strategic advice as well as specific recommendations for individual sites. Thus, within that modernization plan, there should be a SCADA section that broadly defines n What exactly a SCADA system is supposed to achieve; n Which sites should eventually receive SCADA equipment, and for what specific purpose(s); n What tangible and intangible benefits are expected to flow from the implementation of the SCADA system; n How the SCADA system will work, by itself as well as within the irrigation distribution system as a whole; and n How the SCADA system will change operations. SCADA Plans Once it is decided to use some form of SCADA as a tool, the next step is to plan the details. A detailed “SCADA Plan” or similar document should be developed—ideally by experienced consultants who have a documented track record of field success (beyond a history of writing plans). That plan will seek to provide: n A concise redefinition of the SCADA project scope, purpose, and anticipated control strategies. Note the following prevalent problems: n Many years pass between planning and project initiation. In that time frame things can change. n Large civil engineering firms tend to omit this part, forcing system staff and integration firms (defined below) to scrutinize hundreds of pages of contract documents that fail to address doubts—or the simplest basic questions—about what the SCADA project was supposed to accomplish in the first place. n An opportunity to re-evaluate and organize budgets to ensure sufficient funds to cover uncertainties and long-term maintenance. n A formal document for system staff and any consultants to contemplate and discuss before formally deciding—in writing—on as many details as necessary (more details are better). 154 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) n A standalone document to submit for proposal and bidding from integration firms (see box), Integration firms (also known as integrators) specialize in tasks such as including: radio testing, installing sensors (for example, gate positions, water levels, pressures), connecting wires to field panels, assembling all the components n In-depth component specifications, by site within the field panels (for example, battery controllers, radios, PLCs, relays, (field and office): this is quite detailed. grounding cables, and so on), designing radio or satellite antennas, installing n Installation instructions for many of the sen- all the SCADA-related components in the field, testing communications to the sors. For example, water-level sensors must office, developing the screens and data archiving processes in the offices, and so on. Integration firms are not civil engineering contractors (and con- be installed at the correct locations relative versely, a civil engineer’s skillset does not include what integration firms do). to gates or flow measurement devices; still- The SCADA plan provided to integrators is similar in concept to construction ing wells designed for automation may be drawings and specifications provided to the contractors who construct new quite different from stilling wells designed check structures and pumping stations. Integrators are typically not qualified for manual reading of water levels. to select, tune, and program automation routines into PLCs. n Distribution of tasks and standards of work. If automation is involved, there must be close coordination between the integrator and the automation specialists who write the control code. Ideally, the automation specialists will provide the details of all the input/outputs needed (function, signal form, identification) for every automated site as part of the SCADA plan. This detail is needed so that integration firms have a good under- standing of what they are bidding on. SCADA History Large centralized SCADA systems have been used in large irrigation canal systems since the 1970s. Since then, the relevant hardware and software have been fundamentally transformed. Widespread adoption of SCADA in various forms began in smaller irrigation systems in the late 1990s in the US, Canada, Australia, and other countries. The benefits of SCADA are indisputably appar- ent to many system managers in those countries. The present status of SCADA might be described as follows: n For irrigation systems with extensive SCADA systems, the focus is shifting toward developing in-house technical skills, op- timizing maintenance, expanding the system, and budgeting for keeping up with shifts in technology (replacing obsolete hardware). n For irrigation systems without SCADA systems, there remains a difficulty in understanding what is being proposed, and how to compare alternative quotes from SCADA vendors. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 155 Getting Started The components for initial success are strategic or technical. Strategic n Have the support and buy-in of the system’s board, managers and operators. n Have a good design concept that supplements a long-term, prioritized, strategic plan. n Allocate a sufficient initial budget, including adequate contingency funds. n Identify and allocate sufficient long-term budget to pay for subcontracted or in-house labor to perform routine maintenance, replacement, and upgrading of both physical components and software (approximately 15 percent of the initial cost, per year). n Develop a plan to conduct a generous multiplicity of verification processes and intermediate quality-control procedures. n Begin some level of training for managers, operators and technicians before starting any construction, then intensify the train- ing and specialization as the project proceeds. n Have a preliminary system-wide SCADA plan, or vision, but begin small in order to gain experience and success, followed in due course by more rapid expansion. n Identify a system representative who can devote the time necessary to document progress and verification steps, and who has the authority to withhold payments if and when necessary. n Locate local integration firms that can provide excellent technical field support and excellent documentation. If these firms are not available, the expertise must be developed in-house with the government agency. Technicians must be paid well and properly supported, or they will quit their positions after training and move to more lucrative jobs. Irrigation department staff are rarely qualified or trained for SCADA work, so an independent specialist team must be developed. A good example of this approach is in Punjab province in Pakistan. n Begin with simple remote monitoring, followed by perhaps a few gates operated by remote manual control, followed by one or two gates that are automated using distributed control. There are numerous lessons to be learned, and mistakes will be made, but they can be corrected. This is a progressive implementation of increasing complexity for a SCADA network. Technical n Designate a single project manager to track and take responsibility for resolution of issues. n Use a contracting framework that motivates firms to finish the job and incentivizes rapid response and professionalism. 156 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) n Develop thorough specifications and implementation plans before issuing any contracts for materials. n Use only industrial, off-the-shelf components that feature open protocols—all devices should be replaceable by comparable products from a range of various manufacturers. n Avoid proprietary systems and communication protocols that can be understood and serviced only by a single corporation or individual—use only well-documented, open architectures. n Choose a system that is expandable. n Ensure that control constants and other parameters are available to authorized users (not, in effect, hidden). n Plan, assemble, and test everything in a comfortable environment before field installation. n Install redundant sensors for all control-related parameters. n Require complete documentation and deploy independent quality-control review prior to payment. Monitoring—The First Implementation Step in SCADA SCADA can be used to monitor operational parameters such as water level, flow rate, gate position, or any other value that can be represented with an electrical signal. Generally, the monitored data are temporarily stored on-site in a data logger or similar hard- ware. The data are then sent periodically to a central location for archiving, display, reporting, and analysis via wireless telemetry (cellular, satellite, VHF radio). There are two common directions irrigation system managers take in monitoring: 1. A complex approach with the following characteristics: n It is expandable for later remote manual control or distributed automation control. n Being expandable, all field and office components must constitute a sturdy foundational array, with special attention given to the future requirements of two-way radio communications (note that remote monitoring requires only one-way communi- cation), security firewalls, database creation for archiving of information, and so on. n It requires a SCADA Plan with details. n It requires an excellent integration firm. n All the communications systems, base stations, and so on are nearly always owned by the irrigation system itself—as op- posed to utilizing third-party platforms or communications networks. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 157 2. A simple approach with the following characteristics: n It is not expandable for later remote manual control or distributed automation control. n It is fairly easy to implement quickly. n It has a high chance of success. n It does not usually need the services of an integration firm. n It does not usually require detailed specifications. n It allows for a separate, parallel, complex SCADA system to be installed later for remote manual control or distributed automation. n Irrigation systems require the purchase and installation of turnkey commercial packages. Most commercial SCADA moni- toring packages are designed to use third-party communication networks, including cellular and internet networks, and third-party computing servers (virtual server hosting). Option A: 3rd/4th party host This simple approach can provide important information regarding flow 3rd party satellite servers Web interface rates, the status of tail-end pools of canals, and so on. The irrigation system operators almost always appreciate this information, and it provides an op- portunity to learn what types of information are most helpful for operation, 3rd party satellite how the information should be stored and displayed and distributed, and so gateway Internet on. In general, field operators can view the same data on their cell phones as can be seen in the office. This approach is illustrated in the figure on the Copper or right. Remote site data loggers and sensors fiber networks Option B: Cell tower Various public data paths are used in typical commercial monitoring packages. In most cases, systems pay either a monthly or annual subscription fee for data hosting and other services, and/or cellular/satellite communication fees per data unit transmitted from the field. Depending on the vendor, the entire system may use multiple third- or fourth-party services, such as: n Telemetry—cellular and satellite providers charge per megabyte transferred. n Hosting—some vendors may host system data on a vendor server, or pay for third-party services such as Amazon to rent space on cloud-based virtual servers. n Web portal/user interface—like the data themselves, the web portal used by systems to access and download data may be provided by the vendor itself or others. 158 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) Through the web portal, data can be displayed in various ways: n Real-time parameters n Trending of values plotted in charts over time n Databases and spreadsheet reports. The commercial system packages usually include: n Field hardware to measure and temporarily store data n A communications system to send that data back to a central location n Software to archive and serve the data to users. Sometimes the software runs on third-party hardware; other times the project owns everything. Some third-party systems include a data collection and hosting service, which must be subsequently stored and served by the package provider. Therefore, in addition to the initial cost of the hardware, users pay monthly or annual service fees for data hosting. Data hosting refers to a third party aggregating and serving data via a web portal to an internet- connected device SCADA to Support Remote Manual Control and Automation As noted above, SCADA involves much greater detail and complexity for two-way communications and control of actuators on gates and pumps than it does for remote monitoring alone. The images below illustrate some typical components. 1 2 3 1: An ultrasonic sensor measuring the water level upstream of a flow-measurement flume, alongside a submersible pressure transducer (not shown). The conditions shown are not optimal. Floating material can cause an incorrect depth reading; and the lack of a sun screen over the sensor box can cause errors due to high temperatures in the box. The details are important. 2: Field cabinet contents. 3: A touchscreen on the outside of a field panel. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 159 4: Actuator retrofitted to a large, older sluice gate; these can use AC or DC electricity. 5: Low-speed, directional antenna mounted on the exterior of a prefabricated SCADA control building. 6: Large antenna tower with multiple types of antennae, typical of radio repeater stations. 7: Medium-sized SCADA server rack with related equipment at the base station office. 8: Base station with multiple process screens, one screen showing remote-camera images (transmitted via radio) for security. 5 4 8 7 6 160 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) WHAT BENEFITS CAN THIS INNOVATION BRING? For day-to-day operations, the remote-monitoring aspect of SCADA can provide tremendous value to operations and system man- agers. They can quickly gain an understanding of the hydraulic conditions throughout a system without having to travel to those locations. In any case, traveling only enables a person to see one site at a time, whereas SCADA facilitates continual monitoring of the status of multiple locations throughout the project. As system modernization progresses to remote manual operation (and/or automation) of the headings of canals, flow rates into those canals can be changed with little effort from a remote location—either by an operator with a cell phone or from the main office (depending upon established protocols and security structures). SCADA is particularly useful for monitoring in situations where travel is dangerous or difficult. For example, heavy rains may make travel to key sites almost impossible at certain times of the year. SCADA is usually considered to be an essential technology to accompany PLC-based canal and pump automation—if for no other reason than that there is a high probability that sensors, electricity, or other local aspects can fail at some point. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Successful SCADA projects are highly feasible if they are approached carefully with sufficient advance planning, budgeting, and quality control. For success, they should evolve gradually from simple monitoring to eventual complexity (if needed). TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Technical specifications are used to set the minimum requirements for the procurement, assembly, and installation of SCADA com- ponents and to address service, workmanship, and documentation standards. Good specifications are useful for n Integrators—so that they can accurately establish job estimates; and n Quality control—a written record of technical and workmanship details is a prerequisite to verifying and enforcing compliance. Good technical specification manuals can exceed 100 pages. Some important specification considerations are provided in the sub- sequent sections. Note: Many of these specifications do not apply to the situation described earlier as simple remote monitoring. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 161 Sensor Specifications To minimize future problems, good sensor specifications define: n Acceptable performance in terms of n Accuracy and resolution n Error compensation n Environmental ratings n Output signal compatible with the PLC n The sensor location relative to each structure and to installation details such as shading, venting, termination, and stilling well details in order to minimize systematic measurement errors n Shading and venting requirements to minimize daily temperature fluctuations. RTU (Field Panel) Specifications n Use industrial-grade components with adequate environmental ratings. These are typically more expensive, but are a small percentage of the total project cost. n Consider specifying panels that are UL508-listed (a set of safety-related standards for electronic control systems used in United States work environments) to encourage better design and fabrication quality as well as industry standard labeling. n Consider special shading and venting requirements to maintain enclosure temperatures under 120° Fahrenheit (roughly 49°C). Radio Path Surveys There are two kinds of radio path surveys used to design and verify wireless communication networks: n Theoretical, software-based surveys to develop workable initial designs from a remote office; and n Physical field packet tests which involve sending data across physical radios temporarily installed in the field. These tests are used to measure field performance and to verify compliance with project specifications. Both are recommended. The field packet tests should provide documentation of: n Remote site location (latitude and longitude) n Antenna height, type, gain and azimuth 162 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) n Test equipment: n Radio manufacturer, model, frequency, band, transmit power n Cable type and lengths n Component and connection types and quantities n Over-the-air distance between antennas n Signal quality measurements: n Received Signal Strength Indication (RSSI) in dBm n Signal-to-noise ratio (SNR) n Packet test: n Number of data packets sent n Number of packets/bits received and dropped (error rate). The intention is to provide results that are repeatable and form a benchmark for future tests. Communication Protocols Communicating data is one of many fundamental SCADA system services. Communications occur within the SCADA network at several levels: n Sensors to PLC: n Single parameter—most sensors output a single analog value (such as water level or gate position) n Multiple parameter—velocity or flow measurement devices and water quality probes n PLC to other devices (OIT, radio, HMI server) n HMI (base station program) server-to-client computers or mobile devices. The following section provides an overview of the various communication protocols used in SCADA systems, with some recommendations. n Single parameter sensors. Single parameter sensor-to-PLC communication protocols should be simple and standardized. For example, 4–20 mA current loops, to the extent possible, for all single parameter sensors (such as water level or gate position); SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 163 4–20mA current loops are a universal analog signal format for industrial sensors. By specifying a standard signal type, future sensor replacement expenses are minimized because n It is one of the most widely compatible analog signal formats for sensor and PLC applications—selecting something less common unnecessarily limits sensor and PLC options; and n No PLC programming is necessary when failed sensors are replaced. The same is not true for other communication meth- ods, such as MODBUS, an open-source framework (see below). n Multiple parameter sensors. A multiple parameter sensor is one that measures multiple values simultaneously, such as temperature, water depth, and salinity. These require a special type of connection and communications software between the PLC and the sensor. The current default communication protocol for multiple parameter sensors is MODBUS. The SDI-12 protocol is a less common alternative and typically used for very remote weather stations. n PLC-to-OIT (panel display) communication. This communication path is also multiple parameter because numerous values are displayed on the OIT simultaneously. Hence, MODBUS is the most common protocol for this application. HMI (Office Software) Specifications n Use industrial, well-tested, and fully supported HMI software n Minimum specifications: n The HMI layout, content, functions, units, colors, and so on n Archiving and backup processes n Add-ons such as n Automatic alarm-notification systems n Any automated reporting software n Remote-access capabilities n Consider the following acceptability criteria: n No greater than 2% of poll or response failures n 99.5% uptime. Documentation Specifications In general, the documentation of a custom SCADA system should be sufficiently detailed to enable a reasonably skilled person to maintain, support, or modify the system without the need to research or investigate it independently. In most cases, this means the 164 | SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) documentation may need to be hundreds of pages long. Fortunately, most of this information is extremely familiar to good integra- tors, and in any case amounts to standard internal design documents that are developed for the project by default—thus the SCADA system owner is simply asking for an accurate as-built copy. An abridged list of key documentation items includes: n Hardware and software information: n Cut sheets (specification sheets) and manuals n A bill of materials for each site listing a manufacturer, part number, and quantity n All software licensing, account, and payment information n Firmware information n Configuration: n As-built and labeled wiring diagrams that trace all wires from end to end, including terminal identification n Tag databases n Backup software n Backup, as-built application files n Documented configuration settings for all software and hardware n Sensitive information: n Complete password and security credential lists n IP and networking data, including OSI Level 1–3 data, and network diagrams n Base station cabling diagram n User operations manuals (step-by-step instructions) for n Calibration n Common monitoring and control tasks n Recommended maintenance schedules. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) | 165 SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING AND SERVICING n A good SCADA Plan is necessary, and it should fit within the goals and objectives of the irrigation system Modernization Plan. n The weakest technical link is the availability of personnel or companies that can provide good integration services. If good inte- gration companies with experience in irrigation systems are not available, the agency must carefully nurture in-house, pragmatic expertise, using experienced, hands-on consultants as instructors. The trainees may need to be sent abroad to receive portions of this training. n Satisfactory performance, warranties, and excellent, detailed documentation must be specified and enforced through payment penalties for non-compliance. n All equipment and components must be off-the-shelf industrial grade. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY n PLC-based automation n Improved procedures within the system for responding to unexpected changes n Improved data management n Improved analysis and understanding of operations. SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) 166 | STAFFING FICHE 3.7 Staffing BRIEF DESCRIPTION OF THE INNOVATION Traditional irrigation projects in most countries are underfunded. Properly modernized schemes can provide better water delivery service and improved efficiencies, but suc- cess always requires adequate funding and good staffing. In general, one should not expect reduced annual staffing costs because of modernization; rather, one should focus on the increased benefits it brings. There are always exceptions in which the expenses of operation and maintenance staff are reduced via modernization. This often occurs in projects in which smaller, lateral canals that are difficult to operate and maintain are converted into gravity pipelines. Some key points regarding staffing in modernized projects are: 1. In most modernized irrigation projects, staff remain in the project for decades. In contrast, many traditional, government-operated, irrigation projects are character- ized by: a. Engineers and managers who, every several years, may rotate between projects or even switch entirely from irrigation to some other line of work, such as roads. b. Young engineers who may stay in a project for a few years only to gain experience, after which they leave for more stimu- lating, better-paying positions. For modernization of traditional, government-operated irrigation projects, it is therefore important to address this issue so that there is development of knowledge over the years, and that knowledge is retained. 2. Staff must have a mindset of providing service as opposed to being the “rulers” of the off-farm irrigation system. This mindset must be accompanied by customers (farmers or water user associations) that also appreciate the limitations of the water delivery service that can be provided to them, as well as an agreement between the two groups to adhere to a set of clear, contractual rules and expectations on the part of the water supplier and the customers. STAFFING | 167 3. Most modernized irrigation projects do not have low-paid field operators who live at or near every major control structure. Rather, they have fewer but higher-paid field operators who are highly mobile, are authorized to make quick, on-site deci- sions, and operate over large areas rather than at single structures. The switch to such a more mobile, energized, and decision-making staff requires a. good, quick access to the control sites in the field under all weather conditions; b. consideration of how to prevent vandalism at field sites if operators are not on location continuously; and c. excellent communication between the field operators and the office. 4. Automation does not remove the need for field staff. Instead, automation enables field operators to shift their activities away from low-level tasks such as making gate movements and toward higher-level responsibilities, such as dealing with work-relat- ed issues, and performing daily maintenance tasks, communications with farmers, checking for problems such as vandalism or unauthorized water diversions, and so on. Also, it is rare that all the structures in a project will be automated. There are almost always many daily human interventions needed. 5. Field operators are not expected to understand and troubleshoot electronics and communication systems. Specialized em- ployees are needed for this support, who may need to be hired from outside normal irrigation department hiring channels. 6. Most traditional irrigation projects have senior staff who were trained in structure design. In contrast, senior staff in modern- ized projects have a different focus—their training emphasizes personnel management, customer relations, and managing the real-time operations of a dynamic, responsive irrigation network. 7. Staff with 20 years of experience in old, inflexible, and deteriorating irrigation projects are often the most resistant to—and sometimes are unsuitable for—making the changes required for successful modernization. 8. Enforcing rules, and stopping water theft, are two highly sensitive issues. Modernized irrigation projects must confront these issues head on or else the concepts of equity and good service will remain elusive. Field operators are often expected to act as policemen, but they do not have adequate training for conflict management and rarely receive adequate administrative and political backup when they attempt to enforce rules. Solutions to this have included the active involvement of the army, using local law enforcement agencies and courts, and legalized law enforcement groups formed within the irrigation project itself. There is no single universal best solution. WHAT BENEFITS CAN THIS INNOVATION BRING? The proper question is: What will happen if changes to staff attitudes, skills, and functions are not made? The answer is: The invest- ments in modernization will often be wasted. 168 | STAFFING HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Difficulties with Large Government Organization Changes There is nothing technically infeasible about re-orienting staff. But there are usually significant institutional challenges to making the necessary staffing improvements in large government bureaucracies. In Mexico, as an example, the federal government was unable to effect a transition to modernization within the government irriga- tion agency (including the collection of adequate water fees). The solution was to turn over the operation and management of many irrigation projects to water user organizations (WUOs), who hired professional staff. Larger projects tend to have a combination of independent, smaller, water user organizations (“modulos” in Mexico) that are re- sponsible for the operation and maintenance of the smaller canals, and a single, larger water user organization (“distrito de riego” in Mexico) that operates and maintains the major canal network. For example, in the Mexicali Valley, which has about 200,000 irrigated hectares, there are 21 modulos and one distrito de riego. The Board of Directors of the irrigation district is comprised of a representative from each of the modulos. The Mexican transition required changes to the country’s Water Law and extensive capacity building. The modulos and irrigation districts typically cut many of the previous government staff positions that were not contributing meaningfully to operation, mainte- nance, and modernization. The remaining new staff are more professional and efficient. In California, the US Bureau of Reclamation originally operated and maintained several large irrigation canals that supplied water to multiple irrigation districts (WUOs). Dissatisfied with the service provided, consortiums of smaller irrigation districts formed special local water authorities under California water law to assume the operation and maintenance functions of each large canal. In other words, the cumbersome federal bureaucracy was too difficult to change, so an alternative was developed. Large Government Agencies May Not Be Structured to Meet the Needs of Dynamic Irrigation Situations Government agencies tend to have very arduous, lengthy equipment procurement and contract approval processes, whereas irriga- tion projects must respond very quickly to changing conditions—often within a day or so. Second, many government irrigation agencies cannot effect internal change because they suffer from inadequate funding and are unable to hire or fire personnel on the basis of performance. As a result, irrigation projects can morph into quasi-independently functioning systems, with their own local government “kings” who enjoy the power and benefits that can be extracted by virtue of their authority and positions. They become vested interests, with goals different from those of the agency they were selected to head. This is the diametrical opposite of the concept of an irrigation project administered with a service mentality. STAFFING | 169 The relevant questions that should be asked are these: (1) Is the government irrigation authority model in that particular country ca- pable of making the necessary staffing changes that will transform a project into a dynamic, service-oriented, efficient business? Or should a different model be explored, tested, and adopted? (2) If a different model is adopted, typically, the government will almost certainly need to have some level of involvement—but at what levels, and for what functions? DESCRIPTION OF THE INNOVATION Effective Staffing Requires Appropriate Skills and Support Modernized staffing requires skills, support, and administrative organizations that can facilitate the evolution from irrigation projects that have a top-down operation to projects with a service mentality; from an emphasis on engineering design to an emphasis on actual operation; and from being a mere distributor of pre-arranged flows (decided in advance for weeks or months), to managing an irrigation delivery as a dynamic, flexible, farmer-responsive system. While current staff may collect data that end up just sitting in reports, books, and computer servers, the new emphasis is on col- lecting data that can assist in real-time management. This means that new staff knowledge-management skills will be needed to determine what data are important; how it should be collected and how frequently; how it will be communicated to a central location; how it will be stored, organized and accessed; and how it will be made available almost immediately for operators and managers to utilize. Information management is critically important in the modernized environment. Achieving mobility for field operators may require the construction of all-weather roads or paths along canals, along with the pur- chase and maintenance of appropriate vehicles. Maintenance staff will need to have adequate inventories of replacement parts and supplies, as well as the proper equipment (and training) to efficiently conduct maintenance operations. In some projects, the existing equipment is suitable for slow movement of earth but is entirely unsuitable for quick-moving canal maintenance procedures. The psychological component of work is often overlooked, but professional staff need the support and surroundings that will make them proud of what they do and will enable them to make a positive, transformative impact on the project that goes beyond just patching and trying to maintain the status quo. One overlooked but important influencing factor is office conditions: many irrigation project offices are unkempt, poorly lit and ventilated, with bathrooms that are unsanitary, and employees idling away their time, reading the newspaper, talking on the phone, or otherwise doing next to nothing. Maintaining a goal-oriented, professional environ- ment is an unspoken prerequisite of modernization and of the ability to embrace and implement a service mentality. If a project is going to be successfully modernized, modernization needs to start at offices, where the staff spend the greater part of their day. 170 | STAFFING Chaos is defined here as a discrepancy between true conditions and perceived conditions. As part of the service mentality, it will be essential that senior staff eliminate chaos—which is often quite a challenge, because senior staff often have little awareness of actual field conditions. As an example, remote monitoring of inaccurately measured flow rates is a form of chaos. Claims at head- quarters that water levels are always constant upstream of canal check structures, while the reality shows widely varying water levels, is a form chaos. Basically, problems will not be solved if staff do not acknowledge that they exist. Priorities must be understood The ultimate tasks for most irrigation projects are (a) to provide the best water delivery service possible, with reasonable efficiency, and (b) to not only maintain, but constantly improve the project. Staff must be organized, funded, and properly empowered to fulfill these tasks. Furthermore, the service mentality needed for an irrigation project must extend beyond providing good water deliv- ery service. The support staff, too, must see their job as part of what it means to provide good service because, in supporting the operations staff, they are facilitating the work of those who directly influence the efficiency and responsiveness of the water delivery service. Structures The typical staffing structures of modernized projects may appear at first to be the same as those in traditional irrigation projects. But there are often important differences—in the expertise needed, the chain of command, work attitudes, and work environments. Staff categories may include the following: n Administration, which comprises the project manager and supporting services, such as payroll, billing and collection of water fees, accounting and purchasing, and human resources. n Bureaucratic staff, who handle external regulations/regulators and politicians, and other government agencies. This team is usually also responsible for water resource planning on a big scale—which is different from operations. n Operations staff. This includes technical experts on electronics and communications, a watermaster who is responsible for coordinating water deliveries throughout the system, and the field operators and supervisors. Coordination with water user associations is also done by the head of this division. In many projects, the field operations staff assist with maintenance and light construction when the canals are empty. n Maintenance staff. These include those who operate maintenance equipment and the repair shops, maintain vehicles and canals, and do light construction. n Engineering. This group provides designs for the numerous small construction projects that inevitably crop up—ranging from the design of new turnout (outlet) structures to the replacement of bridges over canals, to defining legal rights-of-way. A fatal STAFFING | 171 flaw for many projects is that the engineering staff are unfamiliar with how the irrigation system needs to be operated. There is often little interaction between the two groups. Engineers should always be required, at least for a short period, to personally participate in the construction and operation of any modifications they have designed that influence water control. n Electrical and pump staff. This team is important in some projects, and almost non-existent in other projects. They need to work in close coordination with operations, maintenance, and engineering staff. The organization of the staff partly depends on the size and type of irrigation project. A large irrigation project requires all the staff described above, plus additional staff for some other functions. But a small, 5,000 ha project (such as a Mexican modulo or water user association) cannot afford such a huge staff. In general, small projects have minimal administrative and bureaucratic staff. Most small projects may only have one engineer, if that. They depend instead on engineering support from private consultants or from a larger government support agency. Small projects also often share SCADA technicians and electrical/pump staff. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS N/a. It may be a good idea to examine the staffing and organizational details of similar, successfully modernized projects before making drastic staff or organizational changes within a project. SPECIAL CONSIDERATIONS FOR STAFFING Additional considerations are: 1. It may be possible to hire private contractors for some functions. Some projects do not own any equipment; others own and repair all of their maintenance equipment. Some projects hire private contractors for routine maintenance, such as controlling aquatic weeds or burning weeds on canal banks. Other projects have staff who do this work. 2. There are choices as to where the “hand-off” point from the operations staff of the irrigation project to others can or should be located. If the irrigation project staff is responsible to deliver water to every individual field, a much larger staff is required than if the irrigation project staff delivers water to groups of individuals such as water user organizations. If the project has many small fields, it is often difficult for the large project staffing structure to properly supervise and adequately pay the op- erators near the field outlets. One of the advantages of installing pipelines in the smaller laterals is that it reduces the staffing requirements of the project by moving the “hand-off” point further upstream. 3. In some countries, such as the US, Canada, and certain Latin American countries, the management units are typically much smaller than those in, for example, India and Pakistan. Self-contained irrigation management units typically vary in size from 172 | STAFFING about 5,000 ha to 90,000 ha; 200,000 ha units are uncommon. As a result of the smaller sizes, staff all know each other and there tends to be a greater sense of accountability than in very large organizations.1 “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY An irrigation project should be thought of as a complex, interdependent system that spans a range of functions, from planning and design to construction, operation, and maintenance. Everything is interrelated. For example, selecting the right water control equip- ment requires staff that, at some level, made the right engineering and construction choices and decisions. The availability of good control equipment then allows the operation staff to provide good water delivery service. 1 This is like attending a small school as opposed to being a student in a very large school, in which most things are impersonal. STAFFING | 173 FICHE 3.8 On-Farm Irrigation Design and Standards, Knowledge, and Support Network BRIEF DESCRIPTION OF THE INNOVATION Knowledge support networks for on-farm irrigation exist in most countries in the form of irrigation departments and agricultural extension services. However, in many countries, especially those in developing regions, truly innovative advancements in irrigation will require renewed efforts to strengthen the capacity of those networks as well as expanded groups as related to modern irriga- tion. Key groups that need targeted capacity building include: n Senior officials in government ministries who develop and design irrigation improvement programs n Mid-ranking officials in agricultural and irrigation ministries who carry out the day-to-day implementation of irrigation improve- ment programs n Private irrigation companies that often provide irrigation designs, install systems, and support maintenance n Private irrigation consultants who offer design and irrigation scheduling services n Farmers and farm employees who are involved in irrigation management. Basic irrigation knowledge and related equipment standards are largely available in the world. The immediate need is not to gen- erate more basic information or conduct more research. Rather, the challenge is to organize the streams of knowledge that are applicable to local conditions, develop or improve training and support centers, and then implement empowerment and support programs to enable farmers and those who work with them to better harness the knowledge that is already available. This fiche considers the two factors that are nearly always needed in developing countries: 1. Strengthening the quality and breadth of irrigation system specifications and performance standards that govern all govern- ment irrigation investment programs, and 2. Developing and strengthening private irrigation industry organizations, such as Irrigation Associations, that actively support education and certification. 174 | ON-FARM IRRIGATION DESIGN AND STANDARDS, KNOWLEDGE, AND SUPPORT NETWORK WHAT BENEFITS CAN THIS INNOVATION BRING? Knowledge supports prudent decisions and actions. Standards are intended to ensure high-quality components and complete irrigation systems. Those standards must be incorporated into specifications for use by well-trained designers, and for proper verifi- cation during and after installation. The benefits of good knowledge transfer and quality control programs include irrigation systems with longer lives, lower pumping bills, more efficient irrigation, reduced maintenance, better management, and higher crop yields. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Good standards already exist for the manufacture of most irrigation components. The challenges lie in: 1. Creating good standards and specifications that define how the components are combined into on-farm irrigation systems which have excellent distribution uniformities (DU) and reasonable pressure requirements, and which can be managed to obtain high irrigation efficiencies. 2. Properly training and supporting a sustainable cadre of professionals who are directly involved in all phases (design, installa- tion, evaluation, and management) of modern on-farm irrigation systems. 3. Development of the will and ability of funding agencies to enforce specifications, and to ensure that high quality equipment is purchased and installed—as opposed to accepting the lowest bid. Success also requires properly written contracts, in which payment is based on performance rather than on mere delivery. Filling the irrigation modernization knowledge gaps in a particular farming sector or region is not a one-size-fits-all project. The type and depth of training must suit the needs, activities, education level, and receptivity of that particular stakeholder. Certain stakehold- ers will have no need to learn about certain subjects, and the depth of training needed on any subject will depend on who it is for. ON-FARM IRRIGATION DESIGN AND STANDARDS, KNOWLEDGE, AND SUPPORT NETWORK | 175 FICHE 3.9 On-Farm Water Reservoirs BRIEF DESCRIPTION OF THE INNOVATION Farm reservoirs are located downstream of canal outlets and typically serve a single large field or several small fields. In areas where the canal supply is inflexible or unreliable, farm reservoirs provide on-farm irrigation with flexibility and reliability. They can also serve as fish ponds, giving farmers a secondary source of income. Farm reservoirs typically serve areas ranging from 10 to 300 ha, but they can also serve smaller areas that are under greenhouse cultivation. WHAT BENEFITS CAN THIS INNOVATION BRING? Reasons to use farm reservoirs are numerous, and include these twelve: 1. Some farmers may want to irrigate only during the day, but canal or pipeline deliveries cannot be stopped whenever a farmer wants them to stop; deliveries typically go on for a minimum of 24 hours at a go. 2. Depending on different factors, there may be a need for variable flow rates, but the off-farm irrigation deliveries typically cannot provide farmers with such a high level of flexibility without considerable advance notice, and even then, usually not. Situations that occasion the need for variable flow rates include these: a. The number of sprinklers operating in a field at a particular time may need to be changed. b. Drip system blocks (areas within a field that are irrigated at the same time) are usually not the same size because as differ- ent valves are turned on and off, the system flow rate changes. c. When multiple irrigators share one single pipeline, it is very difficult to coordinate the timing of all flows. 176 | ON-FARM WATER RESERVOIRS d. Pressurized system filters need extra water for occasional backflushing/cleaning. e. The exact hour at which water reaches the ends of furrows or border strips is unpredictable. In the case of furrows, the flow into the heads of furrows may need to be reduced once water reaches the tail end in order to minimize tailwater runoff. 3. The off-farm irrigation system may deliver water only once a week or so, which is entirely incompatible with the needs of pressurized on-farm irrigation systems. Therefore, a week’s worth of water needs to be received over a short period and then used gradually over the week. 4. In some irrigation projects, upstream farmers irrigate only during the day. The tail-end farmers can use reservoirs to store or buffer the unpredictable flow rates that they receive for better on-farm water management. Examples of this problem, and potential for reservoirs to solve it, can be found in the Nile Delta in Egypt, or in the Jordan Valley in Jordan. 5. In many cases, farmers have a mix of surface (canal) water and well water. The reservoirs provide for a buffer so that a desired flow can be used on-farm even though the inflow is variable. In addition, groundwater with higher salinity can be mixed with lower-salinity surface water. 6. Solar well pumps have highly variable flow rates that can be incompatible with on-farm irrigation management, and that vari- ability can be buffered in a reservoir. 7. The flow rates of deep-well (tube-well) pumps often change by the hour and/or by the season as the depth to groundwater changes. If the pumps are directly connected to a pressurized irrigation system, it is impossible to match the flow availability with the flow demand of the irrigation system. 8. Some wells have high manganese and/or iron concentrations that must be oxidized or treated before the water is put into pressurized irrigation systems. Regulating reservoirs provide the opportunity to do that. 9. The cost of power for a pressurized irrigation system can be high, and some utility companies offer a lower rate per kilowatt- hour (kWh) if farmers restrict their pumping to certain hours of the day. In such a case, they can have canal water flowing slowly into their reservoir over a 24-hour period, then pump it out to the farm at a higher flow rate during the “off-peak” hours when the electricity rates are lower. 10. Some countries, especially in the former Soviet Union, use large pumping plants to supply canals up in the hill from lower- elevation rivers. Some of them, such as Tajikistan, have frequent power outages that dry up canals for hours at a time. If farm water user organizations or individual farmers stored irrigation water when it was available, they could then irrigate without being affected by the unreliable power. ON-FARM WATER RESERVOIRS | 177 11. In some countries, such as Thailand, small reservoirs double up as fish ponds that provide farmers with additional income. 12. In irrigation projects that have sandy canal or well water, the sand settles down in the reservoirs by gravity, providing impor- tant pre-filtration for pressurized irrigation systems. The disadvantages of farm reservoirs include these: 1. Construction cost. 2. Land must be taken out of production. However, this disadvantage is typically more than offset by better water management, which results in more yield per acre on the remaining acreage. 3. Required maintenance to remove aquatic weeds. 4. In some areas, a reservoir could raise the incidence of Bilharzia (Schistosomiasis), a sub-Saharan African, freshwater parasitic disease second only to malaria in its impact on human health. 5. Unless fenced off, reservoirs can be a safety hazard to animals and young children. 6. In most irrigation off-farm delivery systems there is not enough elevation drop at the field outlets to allow for gravity in and gravity out. A pump is therefore typically needed at the inlet and/or outlet. This is discussed in greater detail below. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Farm reservoirs can be found under almost all climate, soil, water, and economic conditions throughout the world. Reservoirs con- structed in sandy soil are the most expensive because they require lining. Additionally, the cost per hectare declines as the area served increases. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION The costs are extremely variable. A 1 hectare, combination and lined reservoir (described later) may cost US$35,000. An excavated, below-grade 1 ha pond may be constructed by simply digging a pit with an excavator. 178 | ON-FARM WATER RESERVOIRS TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Types of Farm Reservoirs There are three main types: (i) completely below grade, (ii) completely above grade, and (iii) combination above and below grade. Most farm reservoirs are either (i) or (iii). (i) Below grade (ii) Above grade (iii) Combination 1 1: Types of farm reservoirs. (Source: Adapted from Short (2016). Ontario Canada AGDEX 753/562, Factsheet 16-009.) 2: Farm combination reservoir. (Note: This pump directly supplies water to a drip system filter station.) 3: Below-grade regulating reservoir. (Source: Tailwater Recovery (TWR) and On-Farm Storage (OFS) Reservoir: Economic Considerations | Mississippi State University Extension Service (msstate.edu)) 2 3 Farm Combination Reservoir Design Combination designs with wind erosion protection Berm top on the inside bank of reservoirs typically have the width Rip rap configuration shown in the figure on the right. The Freeboard Bank design here is more typical of those found in the height 1 1 Maintenance 3 3 zone Total western United States. reservoir 1m depth Cut (3.3 ft) depth Key trench Strip the Dead soil surface Configuration for a combination storage 3m reservoir design (not to scale). (10 ft) ON-FARM WATER RESERVOIRS | 179 Table 1 below provides a range of example dimensions for combination reservoirs with three different gross parcel sizes. Table 1: Example dimensions for combination reservoirs Example Dimension A B C D E F G H Cut depth below ground surface (ft) = 3.1 4.4 2.7 4.9 6.6 9.3 5.8 14.1 Bank height above ground surface (ft) = 3.5 4 4 5 5.5 6 6 7.5 Bottom width (ft) = 117 102 160 135 118 96 156 89 Total reservoir depth (ft) = 6.6 8.4 6.7 9.9 12.1 15.3 11.8 21.6 Required gross parcel size (acres) = 1.0 1.0 1.5 1.5 1.5 1.5 2.0 2.0 Net storage (acre–feet) = 1.5 2.0 2.7 4.2 4.9 5.6 7.2 10.1 Cut depth below ground surface (m) = 0.9 1.3 0.8 1.5 2.0 2.8 1.8 4.3 Bank height above ground surface (m) = 1.1 1.2 1.2 1.5 1.7 1.8 1.8 2.3 Bottom width (m) = 35.5 31.2 48.6 41.1 36.1 29.4 47.7 27.0 Total reservoir depth (m) = 2.0 2.6 2.1 3.0 3.7 4.7 3.6 6.6 Required gross parcel size (hectares) = 0.4 0.4 0.6 0.6 0.6 0.6 0.8 0.8 Net storage (cubic meters) = 1,820 2,421 3,340 5,123 6,010 6,902 8,921 12,435 All the examples have the following characteristics: Maintenance zone around the reservoir = 10 ft (3.05 m) Bank side slopes (inside and outside) = 3:1 (horizontal/vertical) Riprap on the above ground inside (usually required with a 3:1 slope) for wind protection Berm top width = 6 ft (1.8 m) 180 | ON-FARM WATER RESERVOIRS Freeboard = 2.0 ft (.6 m) Dead storage depth = 1.0 ft (.3 m) Cut/fill ratio = 1.3 All excavated soil is used for berm construction Square parcel and reservoir The dimensions are meant only for illustration; decisions such as the width of the maintenance zone around the reservoir and the side slopes have a huge impact on the live storage that can be obtained from a reservoir. Active Storage Volume Requirements for Farm Reservoirs Three different scenarios are provided as examples. Situation #1 The canal water and well water are available during irrigation-only hours at approximately the correct total flow rate, but those incoming flow rates may be variable and may not correspond to frequent minor flow rate changes on-farm. For this case, assume that the incoming flow rates vary unexpectedly by +/- 20 percent over the course of a day, and that the on-farm irrigation system flow requirements vary by +/- 15 percent. The mathematics could be analyzed in great detail, but in reality, no one really knows the exact value of either of these numbers. Points to consider include these: n This type of reservoir is not really a “storage” reservoir that holds water for use several days later. Rather, it is meant to buffer short-term (for example, single-day) discrepancies between supply and demand. Notice that the wording was “single-day,” which implies that adjustments can be made daily if daily discrepancies become too large. n One does not really know if a +/- 20 percent inflow (from off-farm) discrepancy will last a full day or just an hour. The same ap- plies to the on-farm irrigation system requirement. This could be studied in great detail, yet the answers would be completely different at another farm/canal junction. n The design of this type of a buffer reservoir considers both pluses and minuses. It is not always kept full in case of an emer- gency; the target level is half-full. n If there were either a 20 percent positive inflow discrepancy (20 percent more water volume arrives than is used) or a -20 percent negative inflow discrepancy for a day, the operation of the reservoir would attempt to maintain it at half-full. This would allow it to accept either a plus or minus discrepancy. For example, ON-FARM WATER RESERVOIRS | 181 Target inflow = 3 cusecs (cfs) Time period between adjustments = 24 hours Anticipated +/- inflow volume (acre-feet, or AF) = Cusecs x hours/12 = (40% x 3 cusecs x 24 hours)/12 = 2.4 acre-feet = 2.4 AF = (1,233m3/AF x 2.4 AF) = 2,960 m3 n If, on the other hand, the +/- 20 percent inflow discrepancy lasts only a few hours, considerably less storage volume is needed to meet the inflow variations. n The same idea applies to the variable outflow. n The final decision will depend upon the ability of the farmers to monitor the reservoir. If they are willing to adjust their flow rates to match the variations in delivery and the buffer storage, then they will need less buffer volume. The example shows that a designer needs to have a good idea of how the supply system operates, as well as the needs on-farm. There is no typical size for a buffer reservoir meant to buffer hourly variations. Situation #2 A farm buffer reservoir receives water continuously, but farmers irrigate only during daylight hours. For example, Target inflow from the canal = 3 cusecs (cfs). It varies over time but is averaged out over a 24-hour period. Farmers irrigate only 8 hours/day (1/3 of the time) with a flow of: 24 hours/8 * 3 cusecs = 9 cusecs Active storage volume required = (Hours of storage) x Inflow/12 = 3 cusecs x 16 hours / 12 = 4 acre-feet (4,932 m3) Plus, perhaps 15–20 percent more capacity due to uncertainties. Table 1 shows that such a reservoir might require about a gross of 1.5 acres (0.6 ha). But the serviced irrigated area would likely be about 200 acres (78 ha). If production were to be increased by 1 percent per acre due to improved irrigation water management, 182 | ON-FARM WATER RESERVOIRS the lost area would be more than compensated for. This is, of course, a reason so many farm regulating reservoirs are used in modernized irrigation projects. Situation #3 Farmers irrigate every day for 8 hours a day, but water arrives only once every 7 days for 24 hours at a time. This is really a storage reservoir to buffer the inflexibility of a rotation water delivery system to meet farm irrigation needs. This becomes quite expensive. This problem is approached as follows: Assume the same continuous flow requirement as for the previous examples of 3 cusecs. The on-farm irrigation rate is the same as the previous example: 9 cusecs Then the water delivery from the canal must supply 7 days of water, during a 24 hour period. That flow rate is: 3 cusecs x (7 days / 1 day) = 24 cusecs The volume of storage that is needed can be calculated as: Volume needed = [(Continuous flow rate req.) x (Hours between deliveries) – (Outflow rate x Hours of outflow during y)] / 12 deliver­ = [(3 cusecs x 7 days x 24 hours/day) – (9 cusecs x 8 hours)] / 12 = [504 – 72] / 12 = 36 acre-feet (44,388 m3) This would likely be very expensive, and points to the problem of using a rotation water delivery system to meet the needs of farm- ers who want to adopt pressurized irrigation methods that require daily irrigations. Farm Reservoir Seepage There is no standard for the lining of reservoirs because the conditions are so variable. For example, if the reservoir is in a rice project with a high water table, there will be little or no seepage from an excavated buffer reservoir. But if the reservoir is largely above the ground on sandy soil, some seepage prevention/reduction measures will be essential. Solutions almost always depend upon the cost and availability of materials and equipment. Examples of common solutions are: 1. Excellent vibratory compaction of medium-textured soils during construction, with careful attention to moisture content and the thickness of each compacted layer. This can be the least expensive solution and can be very effective if the soil texture is suitable and there is good quality control during construction. ON-FARM WATER RESERVOIRS | 183 2. Placement of a layer of bentonite clay about 1 ft (30 cm) under a covering layer of soil. This is often selected where there is an excellent local supply of bentonite. 3. Some type of non-porous, thick geomembrane on the top of the soil. There are significant variations in the durability and cost of various geomembranes, and laboratory tests often do not indicate longevity in the field. These can be excellent but ex- treme prudence must be used, and existing installations (more than 5 years old) should be re-visited and checked. 4. Some type of non-porous geomembrane under about 1 ft (30 cm) of soil cover. 5. Concrete lining. This will inevitably crack. 6. Concrete over an excellent geomembrane. A few geomembranes have been developed specifically for use with a 3-inch (8-cm) concrete overlay. This combination is the most durable available and prevents seepage while also providing a durable surface so that the lining is not damaged by animals, humans, or maintenance equipment. In the case of any water-tight cover of geomembrane or concrete, pressure relief valves must be installed in the lining to prevent floating of the lining if the surrounding soil has a high water table. Wind Erosion It is common to install riprap or concrete slabs on the higher parts of reservoir banks to prevent erosion due to wind waves. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Farm irrigation ponds (sometimes called tank irrigation), especially when combined with simple aquaculture, have been widely adopted in many countries by very poor people. They are simple to excavate. The above-grade and combination reservoirs some- times have pumps both in and out, which makes them more complex. The overall results are improved economics for farmers, plus better irrigation efficiencies (a major environmental consideration) due to the flexible and dependable availability of the irrigation water. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING In many countries, the farm reservoirs are built by farmers—especially if they are the below-grade type. If bank heights are greater than 10 feet (3 meters), many jurisdictions will require that the design be approved by a licensed civil engineer. Local extension service training about fish, fish diets, harvesting, and processing techniques is needed for aquaculture. 184 | ON-FARM WATER RESERVOIRS “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Aquaculture, pumps, electric power supply, and pressurized farm irrigation systems. LINKS Shortt, R. 2016. Design, Construction and Maintenance of Irrigation Reservoirs in Ontario. Factsheet 16-009. Ontario, Canada: Ministry of Agriculture, Food, and Rural Affairs. https://files.ontario.ca/omafra-design-construction-maintenance-irrigation-reser- voirs-16-009-en-25-03-2021.pdf New South Wales (NSW) Agriculture. 1999. On-Farm Water Storages: Guidelines for Siting, Design, Construction & Management. https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0010/163990/on-farm-water-storages.pdf Belén, L-F., J.F. Velasco-Muñoz, and M. Piquer-Rodríguez. 2020. “Contribution of Irrigation Ponds to the Sustainability of Agriculture. A Review of Worldwide Research.” Sustainability 12 (July): 5425. https://www.mdpi.com/2071-1050/12/13/5425/pdf Ghungarde, D.S., and S.G. Wawale. 2021. “The Role of Farm Ponds in Agricultural Development: A Case Study of Nivadunge Village in Pathardi Tehsil of Ahmednagar District (M.S.).” Applied Ecology and Environmental Sciences 9, no. 8: 719–723. DOI: 10.12691/aees-9-8-2. https://pubs.sciepub.com/aees/9/8/2/index.html Masuo, A. No date. Potential and Constraints for Intensive Land Use with Pond Irrigation in North-East Thailand. Owashi, Japan: Japan International Research Center for Agricultural Sciences (JIRCAS). https://archive.unu.edu/env/plec/marginal/proceedings/ AndoCH9.pdf Kumar, D. 1992. “Construction of New Ponds and Farms.” Chapter 6 in Fish Culture in Undrainable Ponds: A Manual for Extension. FAO Fisheries Technical Paper no. 325. Rome: Food and Agriculture Organization of the United Nations (FAO). http://www.fao. org/3/t0555e/t0555e06.htm Halwart, M., M. Martinez, and A. Schückle. 2000. “Aquaculture and Farming Systems Development.” Chapter 2 in Small Ponds Make a Big Difference: Integrating Fish with Crop and Livestock Farming. Rome: Food and Agriculture Organization of the United Nations (FAO). www.fao.org/3/x7156e/x7156e03.htm ON-FARM WATER RESERVOIRS | 185 FICHE 3.10 Modernized Surface Irrigation BRIEF DESCRIPTION OF THE INNOVATION Surface irrigation is the only viable irrigation method when water is delivered by rotation without intermittent storage—which is the case on a large percentage of the world’s irrigated acreage. It is suitable for fields that are well leveled and have soils of uniform consistency. Two major advantages are the low pressure required—often no pump is needed—and the simplicity. Modernized surface irrigation can convert inefficient, traditional surface irrigation from a water-spreading system into a well-controlled irrigation method with reasonable uniformity of water infiltration across a field. Modern surface irrigation has several variations, including these: 1. Paddy irrigation, in which there is continuous standing water. The major modernization component for paddy (rice) irrigation is excellent land leveling. 2. Sloping furrow irrigation. This is primarily used for crops such as cotton, corn, sugar beets, and vegetables. Most of the surface area is raised into wide or narrow beds (depending on the crop) with tillage equipment. The field is irrigated occasion- ally (for example, once every 14 days) by running water down the furrow (the low area between the beds). For good uniformity, there should be no more than about a 40 percent difference in opportunity time (the time during which free water is on a given segment of the furrow) between all the points in a field. Achieving relatively equal uniformity on long, sloping furrows requires tailwater (end) runoff. On shorter level furrows, this can be achieved without runoff. 3. Sloping border strip. Land grading is done to create strips of land (3-60 m wide) with a slope down the strip but no cross- slope, with raised borders between the strips to contain water within single strips. It is used for orchards and vineyards, and for many other crops planted on flat ground—including almost all small grains, alfalfa, safflower, and pasture. In contrast to furrow irrigation, about 90 percent of the ground surface is covered with water during an irrigation event. Infiltration rates are therefore much higher. As with furrows, the rule of no more than 40 percent difference in opportunity time along the border strip holds, but because of the high infiltration rates, the irrigation water can often be shut off at the head end before the water advances to the far end. If managed properly, high uniformities can be achieved with no surface runoff. 4. Level basins. These can be either with furrows or with no cross slope, but resembling border strips in appearance. They have no slope, so they must be relatively short and have high flow rates to quickly move the water across the entire level (flat) basin. The same rule applies regarding relatively similar opportunity times as with any other surface irrigation method. 186 | MODERNIZED SURFACE IRRIGATION WHAT BENEFITS CAN THIS INNOVATION BRING? The performance of surface irrigation can usually be greatly improved with the following investments: 1. Land leveling. This is typically the single most important intervention. It is described in more detail in Fiche 3.11: Land Grading, Leveling, and Planing. 2. Improved water delivery to the furrows, border strips, or basins. Most traditional surface irrigation systems have crude field ditches, and irrigators use a shovel or other tool to fill or empty holes on the earthen sides to allow water to flow into small areas of the field. Improving this is a focus of this fiche. 3. Irrigating different soil types differently. Because different soil types have 1 different infiltration rates, an hour of irrigation on one soil type may infiltrate 2 two to four times as much water as on another soil type. 4. Building the practical capacity of farmers regarding correct length of furrow, border, or basin, with correct flow rates along them, for correct durations of time. This requires harnessing the services of well-trained local experts who thoroughly understand surface irrigation evaluation procedures. 5. Proper tillage equipment for shaping good furrows and crop beds [see Attachment 3: Improved Tillage and Furrow Formation]. 1: Traditional furrow irrigation with poorly shaped furrows. 2: Improved furrows, demonstrating shallow residual water after irrigation of alternate furrows. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Surface irrigation is not only feasible, but relatively inexpensive for most row, grain, and pasture crops such as alfalfa. The requirement is that the fields should have relatively mild, uniform slopes—zero slope is acceptable, one percent is about the maxi- mum—with uniform soils within individual fields. The equipment, if properly selected, is simple and robust. MODERNIZED SURFACE IRRIGATION | 187 Poor Investments Two common practices should be avoided: 1. The use of computer models to design and manage surface irrigation systems. Computer modeling is an interesting but im- practical idea because of the high level of sophistication it requires. To put it simply, a model is only as good as what is inputted into it, and these irrigation models depend on having excellent knowledge of soil infiltration characteristics and roughness. Soil infiltration rates are highly dependent on the soil texture, soil structure, and the percentage of the wetted area—a wide furrow has a different intake rate than a narrow one—as well as the quality of the irrigation water. These parameters can change sig- nificantly from minute to minute, and throughout the irrigation season. For example, soil roughness, which impacts the depth of water in a field and the rate at which water advances in it, changes as a crop matures, and as soil clods disintegrate over time. Rather than computer models, therefore, designers should focus on the fundamentals: using relatively short furrows, bor- ders, and small basins, with large, well-controlled flow rates. Existing systems can be evaluated to determine how to optimize the irrigation scheduling and improve the distribution uniformity of water infiltration throughout the field. 2. Surge irrigation, automated on-farm gates, and cablegation. Although these devices have all worked well in a few locations, they are complicated, often fail, and often do not produce the intended results. They are not widely used and should be avoided in programs that do not already have sophisticated, successful farmers. DESCRIPTION OF THE INNOVATION Improved Water Delivery to Furrows, Borders, and Basins There are a variety of hardware options for improved water delivery. Four popular options are described below. Earth Ditch with Siphons and Check Dams Two major innovations (as compared to typical earth ditches) are the introduction of siphons and of check dams. Siphon pipes are made from either plastic or aluminum and convey water over the ditch bank and into individual furrows, basins, or border strips. Check dams are temporary dams, made of canvas or plastic and supported by boards, that are used to raise the ditch-water level above ground. Siphons from earth ditch before planting of furrows. 188 | MODERNIZED SURFACE IRRIGATION 1 2 1: Canvas dams to raise the ditch-water level on a sloping ditch. 2: Siphons on corn (maize). Classic problems with earth ditches include seepage losses, weeds, and the higher labor effort (compared to other options such as gated pipe), including the need to destroy and rebuild them between irrigations so that tractors can easily turn around. Concrete Ditch and Siphons or Gates Slip-form concrete ditches are common forms of on-farm ditches in some areas because of their neatness and reduced seepage. The most common problems in development projects include (i) poor soil compaction and preparation before installing the con- crete, (ii) insufficient capacity, (iii) inadequate quality control of the concrete mix and thickness, and (iv) excessive elevation of the ditch above the ground surface. A ditch water surface 0.35 meters above ground is adequate. The slip-form construction technique is age-old and involves first over- excavating the soil, and then refilling the excavated zone with compacted soil. A trapezoidal ditch shape is then excavated in the compacted soil. The concrete is continuously poured into a “slip form” that is winched forward at a constant rate. Although the concrete lining lacks steel reinforcement with bars or mesh, fibers are sometimes mixed in at the concrete batch plant for extra strength Compacted and shaped soil prepared for slip-form lining. MODERNIZED SURFACE IRRIGATION | 189 1 2 Tractors cannot drive over concrete ditches and must therefore turn around in the field between the ditch and crops with furrows. This cre- ates a lost bare area (as seen on the left). But this is not a problem with concrete ditches used on basins and border strips. Buried Pipe and Riser Valves This combination is common in some areas and eliminates the prob- lems with ditches. More land can be farmed, less maintenance is required, and control is easier. The pipes can be supplied by gravity if they have a sufficiently large diameter and low friction losses. 3 Typical problems are (i) the pipeline materials are not thick or strong 1: Old slip-form that is winched along. 2: New enough, and (ii) the riser valves are of poor construction. self-propelled slip form machine. 3: Tractor turnaround area between the crop and In areas where this combination is successful, buried PVC pipe is often concrete ditch. used with a minimum pressure rating of 5 bars, one, because of the need for resistance to external soil and equipment loads, and two, because PVC pipe walls can be sufficiently thick to avoid damage 190 | MODERNIZED SURFACE IRRIGATION during transportation, handling, and installation. Designers unfamiliar with these systems often mistakenly assume that the low water pressure means that the pipes can be thin. A typical soil cover depth is about 0.75 meters for plastic pipe. Special durable riser valves are available for these systems. They are typically cast iron, with a rubber gasket for excellent sealing. They are 1 2 sometimes called “alfalfa valves” if they have a special rim to connect with surface hydrants (for gated pipe) or called “orchard valves” if they do not have this special rim. If pumps are used, it is common to pump over G.S. open stands that supply the pipelines/risers. The open stands help to avoid water hammer and 3 ensure a constant flow rate into the pipeline. 4 5 Gated Pipe The fourth option for improved water delivery, gated pipe, has equally spaced gates to match the furrow spacing. It is widely used to supply furrows because it is portable, can be removed or set aside to permit tractor travel, and is easy to use. If growers want to use gated pipe for multiple seasons and/or with a total elevation change exceeding 1.5 meters or so, they must use durable pipe made of materials such as alu- 1: Alfalfa valve being opened. 2: Closeup of an alfalfa valve. 3: Use of a pump into an open minum, special UV-resistant PVC, or thick-walled standpipe. If only one valve is opened at any one time, it will receive the full flow rate. In that (at least 2 mm) lay-flat pipe. case the water is rotated from one valve to another along the pipeline over time. 4: Typical 8-inch (20 cm) aluminum gated pipe with large gates. Pipe joints are long and have gaskets but have no joint retaining system due to the low pressures. 5: Gated pipe stacked in a field. MODERNIZED SURFACE IRRIGATION | 191 Less expensive but shorter-lived, thin-wall, flexible pipe is also used. The thin-walled materials are sensitive to puncture from plant residue and dirt clods. Some materials cannot withstand more than 60 cm of internal pressure, which makes them unsuitable for sloping fields. Thicker lay-flat hose is much more expensive but also much more durable as well as collapsible for transport. 1 2 1: Flexible, one-season gated pipe with blue gates irrigating cotton. 2: Flexible gated pipe. Gates should be large enough to deliver about 20 gallons per minute (gpm) at 1 foot of pressure of 1.3 liters per second (lps) at 30 cm of pressure. Gated pipe diameters of 12 inches (30 cm) are common if they are fed from one end. If they are fed from risers on buried pipe, they are usually shorter and smaller in diameter—for example, 6 inches (15 cm). 1: Short gated pipe sections supplied by an open hydrant over an orchard valve riser on a buried pipe. 2: Gated pipe supplied from a “universal hydrant” from an alfalfa valve on a 1 2 buried pipe. 192 | MODERNIZED SURFACE IRRIGATION TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Initial costs: US$300 to US$1,000 per hectare. Often these systems require no pumping to distribute the water through the gated pipe. Often no pumping; annual maintenance costs are equivalent to about 7.5 percent of initial cost. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Local parts suppliers must be established companies. Concrete ditches require excellent soil preparation and compaction and high- quality concrete. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Gated pipe of short and small diameter sections is lighter, and therefore easier to manipulate than large diameter, longer sections. Concrete ditches and gated pipe reduce back injuries because irrigators expend less effort compared to working in the mud of earthen ditches. Aluminum is very durable for gated pipe but may be subject to theft. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING Gated pipe manufacturers are common in the US and available in Europe. Manufacturing licenses can be obtained for alfalfa valves, gated pipe, and other such materials. Concrete ditches are always constructed very locally; buried pipeline distribution systems require a good knowledge of the very specialized hardware needed for this type of irrigation. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Laser land leveling; improved tractor tillage equipment; irrigation designer training and certification process modeled after the stages and requirements developed by the Fairfax, Virginia-headquartered Irrigation Association (https://www.irrigation.org/IA). PRACTICAL EXAMPLES Gated pipe has been used successfully since the 1940s throughout the world. It is most common in North America. Buried pipe and concrete ditches, used for direct deliveries to individual furrows, is less common throughout the world. MODERNIZED SURFACE IRRIGATION | 193 LINKS Design/expertise: Walker, W.R. 1989. Guidelines for Designing and Evaluating Surface Irrigation Systems. FAO I&D Paper #45. http://www.fao. org/3/T0231E/T0231E00.htm Burt, C.M. 1995. The Surface Irrigation Manual. Exeter: Waterman Industries, Inc. http://irrigationtoolbox.com/IrrigationToolBox/ Section%201%20-%20Soil%20Water%20Plant%20Relationships/Publications/Surface%20Irrigation%20Manual.pdf Manufacturers/distributors: Waterman Industries https://watermanusa.com/applications/ag-irrigation/ Fresno Valves and Castings https://www.fresnovalves.com/ LAND GRADING, 194 | MODERNIZED LEVELING, SURFACE AND PLANING IRRIGATION FICHE 3.11 Land Grading, Leveling, and Planing BRIEF DESCRIPTION OF THE INNOVATION Surface irrigation requires even ground slopes for the even distribution of water throughout a field. A smooth ground surface is required for the consistent advance of water across a field. Smooth even ground also enables farmers to place seeds or plants at a uniform height above the water surface—preventing seeds from either drowning or dying of drought. A consistent ground slope also allows excess rainfall to drain from a field. Often, the first and most valuable investment in surface irrigation is to smooth the soil and redistribute it throughout a field to cre- ate a uniform slope. There is software and equipment available that creates a uniform plane and provides a constant downslope and cross-slope across a field (often called “land leveling”). There are other procedures (software and hardware) that can be used to re-shape a field surface in such a way that the new slope is variable (yet always downhill and not too steep), in order to match the original topography more closely and to reduce the movement of earth required. Procedures such as this that do not cre- ate a uniform slope across the field are often termed “land grading”, although the terms are often used interchangeably. A third procedure—land planing [same pronunciation as “plane”]—involves no software or computations but is accomplished by dragging a special implement across the field to smooth out localized soil surface irregularities. Although land grading is common in some countries, it is still lacking in many irrigation projects. Land planing is less well understood and is rarely discussed in the literature, but it is common practice in North America. WHAT BENEFITS CAN THIS INNOVATION BRING? The results of good land grading and land planing— improved irrigation efficiency, leading to increased yields and crop quality—are well known. Laser-controlled land grading equipment. LAND GRADING, LEVELING, AND PLANING | 195 HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? The techniques are very robust and have a long history of success, with virtually no negative effects unless too much soil is excavated, thereby exposing a hardpan (very dense soil layer) or a toxic soil layer. DESCRIPTION OF THE INNOVATION Most projects begin with a program of land grading, in which field surface elevations are modified to provide a desired slope. This requires equipment that can “cut” soil from high points, then rapidly transport the cut-soil volumes to other lower areas of the field, and subsequently “fill” those lower areas. Sometimes the soil is cut to a depth of one meter, or Demonstration of how a land plane can smooth the soil surface. The scraper blade even two meters, but more typically a large cut may be 0.5 is almost always positioned further back from the tractor than seen here. meters deep. The steps of land grading are: 1. All vegetation first needs to be removed before moving the soil, so that only the soil is manipulated. 2. The ground surface of the field is then surveyed. a. If laser leveling is used for surveying, the survey equipment will serve again for subsequent control of the cut/fill equipment. A rotating-beam laser transmitter is set up in the middle of a field. It is adjusted to project a horizontal beam. Laser receivers are placed on a tractor, which is then driven around the field. Software in effect surveys the field, creates an accurate map of the topography, and determines where and how much to cut and fill, considering the compaction that occurs in the fill areas. The desired downhill and cross slope can then be obtained, whether it be zero (flat) or 0.002 (2 m/1000 m), as an example. b. If land-contour grading procedures are used to reshape a hillier field so that the slopes are more uniform but not in a level plane, a topography map is often developed using standard GPS RTK (global positioning satellite real-time kinematic positioning) survey equipment. RTK equipment is sufficiently accurate for steeper slopes for which land-contour grading is used. Although it is not as precise as laser leveling, it is easier to set up in the field (one base station every 1.5 km instead of one per field) and works well in dusty environments. Also, unlike laser leveling, the computations do not need to be cor- rected for the earth’s curvature on large fields. 196 | LAND GRADING, LEVELING, AND PLANING 3. Commercial software uses the survey data to compute the soil surface cuts and fills that will be made. It automatically com- putes the cuts and fills so that they balance out, considering that the volume of the cuts will exceed that of the fills because the fills are more compacted. 4. Depending upon the land-grading technique used (plane or contour-smoothing), the appropriate transmitting equipment is set up in the field for elevation control. Tractors with earth-scraper or earth-moving equipment are used with receivers and controls that automatically control the scraper blade elevation adjustments. Soil is removed (“cut”) from high points and moved to lower (“fill”) areas. Bulldozers are not used because they are designed to only push soil a short distance. 5. It is often desirable to preferentially ground-apply phos- phorus fertilizer to cuts, because most soil phosphorus is found in approximately the top 40 cm of soil and will be removed from cut areas. A cut/fill map provides 1 guidance on where to place the fertilizer in different dosages, depending upon the depth of cut. 2 After the one-time large-scale soil redistribution that occurs with land grading (to create a new slope on the field), the soil surface will usually need smoothing every year. There can be appreciable soil settling during the first year after land grad- ing. Normal field subsidence and localized soil redistribution by tillage equipment will require annual soil surface smooth- ing. Two types of equipment are typically used for this: 1. One season after the initial land leveling, the soil will have local highs and lows due to unequal settling of the disturbed soil. Laser equipment is again brought to the field, but often with smaller land-leveling equipment connected to a tractor. This equipment moves the soil 1: Land plane with a design in which the frame floats across the soil surface. A blade is located across the middle of the unit. 2: Land plane showing only a short distance rather than all the way across a accumulated soil that has been trimmed from high spots and will soon fill in low field. spots. LAND GRADING, LEVELING, AND PLANING | 197 2. In subsequent years, land planes may be used to smooth out the soil surface. Land planes are simple and use no electronics but do an excellent job of knocking down localized high spots and filling in small depressions. They are not capable of changing the slope of the field. The principle of land planes is that they are very long, with a scraper blade in the middle, and after several passes through a field (often both diagonally and perpendicular) they smooth out localized bumps and depressions. Land plane for a large field. Steel wheels are used. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Large farms may own both land-grading equipment and land planes. But for smaller fields, the equipment is typically shared by cooperatives, or commercial operators are hired to do this occasional work. Because of the simplicity of land planes, it is more com- mon for farmers to own this equipment. Commercial companies charge approximately US$0.15 per cubic meter of soil moved. The tractor, guidance system, and trained technician are the primary factors that govern the cost, as opposed to fuel. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Typically, there are no standards for this work. A project could require an independent verification of final field elevations before payment. Because of edge effects, it is more difficult to be precise on small fields than on larger fields. Some basic tractor specifica- tions and grading/planing specifications would be useful. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS There are no negatives to land grading or land planing if the cuts are relatively minor. The farmers do not need to learn anything new to benefit from the work that has been done. The focus needs to be on providing the equipment and well-trained staff to operate and maintain it. If surface irrigation of any type is to be used, the ground surface must be smooth and well-shaped, so that 198 | LAND GRADING, LEVELING, AND PLANING good irrigation efficiency can be obtained. Conversely, without smooth land surfaces, surface irrigation would be poor and crop yields low. The small fields in many countries require small equipment, or in effect, hundreds or thousands of tractors, guidance systems, and scrapers for laser-controlled units. This in turn means there must be a large-capacity building program for technicians, engineers, operators, and equipment maintenance. Land planing for subsequent years requires minimal support except for the initial purchase or fabrication of the land planes. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING Land grading equipment with laser control is common around the world, and commercial contractors are available. Land contour shaping with GPS (on steeper ground) is less common, but the software is available commercially from a few vendors. Land plan- ing equipment is not known in many countries. Land planes are typically built by smaller local companies; fabrication plans can be purchased from existing manufacturers, and local manufacturing workshops can be established. Dual scraper land grading unit. LAND GRADING, LEVELING, AND PLANING | 199 Land planing equipment is typically owned and operated by individual farmers or a group of farmers because it is so simple. Small scraper equipment for land grading (utilizing GPS or laser guidance and control systems) is often owned by larger farmers who have the necessary technical support and expertise. But the larger equipment, and often the smaller GPS/laser-guided equipment, is owned and operated by local commercial companies. A small-scale scraper with laser receiver and transmitter “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Once the land surface is graded (leveled) to a suitable slope and precision, it is typical to invest in better tillage equipment and water-control equipment. For water delivery, gated irrigation pipe is the most common investment and may be accompanied by buried supply pipe with occasional risers to supply the gated pipe. For large, sloping fields with furrows, tailwater return systems (sump, pump, pipe) are used to return tailwater runoff to the top of the field. PRACTICAL EXAMPLES Laser land leveling has been commercially available since the early 1970s. Since the 1940s, land grading and land planing were common in some areas of the world. Laser leveling was extensively used in Iran in the mid-1970s. Laser leveling was initiated in the Punjab province of Pakistan in 1984 by the On Farm Water Management (OFWM) directorate of Punjab’s provincial Agriculture Department. Later, OFWM directorates in all four of Pakistan’s provinces started providing subsidized laser-leveling rental services to farmers under various projects funded by the World Bank or Asian Development Bank, as well as various schemes financed by provincial and district governments. Its adoption, however, was much faster in the Punjab, where roughly 125 laser units were in operation in 2006, by which time they had precisely levelled more than 283,250 ha (700,000 acres) since the arrival of the first unit in the province. In 2006, the Punjab government decided to scale up the laser land levelling operation by involving private sector service providers, and launched a project titled “Strengthening of Laser Land Leveling Services in the Punjab.” Under this scheme, service providers 200 | LAND GRADING, LEVELING, AND PLANING and farmers were incentivized to purchase 2,500 laser units by providing 50 percent matching grants during 2006–2009 for the provision of services to neighboring farmers at market rates. This intervention was a major development in shifting this service delivery from government to the private sector. As a result, annual laser land- leveling capacity in the province rose from 14,164 ha (35,000 acres) to 300,000 ha (750,000 acres). It was, however, observed that the laser land leveling services were still inadequate to meet the burgeoning needs of the province’s farmers, who had cultivated more than 12.6 million ha (31 million acres) of farmland. The major break- through came during 2012–16, when 50 percent matching grants were provided to the service providers to procure 5,000 laser land levelers Land leveling with smaller tractor and laser-controlled scraper, Pakistan. under the World Bank-funded “Punjab Irrigated- Agriculture Productivity Improvement Project” (PIPIP). It tripled the private sector’s capacity for providing rental services across the province. This project was also a turning point in terminating rental services by the government because of efficiency and transparency issues: all laser units operated by OFWM directorate were disinvested to the private sector. The private sector’s capacity was further augmented through implementing another locally funded scheme in the Punjab that provided 4,000 more laser units during 2015–2018. In total, there are currently more than 16,000 laser land levelers providing services to farmers throughout the province. This resounding success of laser land leveling technology served to promote it in other provinces, such as Sindh and Khyber Pakhtunkhwa, under projects assisted by the World Bank. Based on Pakistan’s success, neighboring Afghanistan also supported the introduction of laser land leveling technology to farmers and service providers under the World Bank-assisted Afghanistan OFWM project, implemented between 2011 and 2019. India is now subsidizing the promotion of laser land leveling interventions within the farming community. Laser land-leveling technology is also being promoted in Cameroon under the World Bank-assisted “Valorization of Investments in the Valley of the Logone” (VIVA) project. LAND GRADING, LEVELING, AND PLANING | 201 LINKS Software for GPS land reshaping on steeper slopes: https://www.optisurface.com Software for laser land grading: https://www.topconpositioning.com/ https://leica-geosystems.com/en-us/industries/agriculture/leica-geosystems-agriculture-solution/construct/ high-precision-land-levelling https://agriculture.trimble.com/solutions/water-management Scrapers for land grading: These are available from most international construction equipment manufacturers. Manufacturers/distributors of land planes: T. G. Schmeiser Co., Inc. www.Tgschmeiser.com Eversman www.eversman.com Snipes Equipment Fabricators https://web.facebook.com/snipesequipmentfabricators/?_rdc=1&_rdr Fab Services Inc. https://fabservicesinc.com/ LINEAR 202 | LAND AND CENTER GRADING, PIVOT AND LEVELING, PLANING SPRINKLERS FICHE 3.12 Linear and Center Pivot Sprinklers BRIEF DESCRIPTION OF THE INNOVATION This fiche describes two similar sprinkler systems—center pivots and linear moves (sometimes referred to as “lateral moves”). Both are well-established technologies. Both have a long pipeline onto which sprinklers are attached (usually at a uniform spacing). Pipeline segments are supported along their span by truss structures, with a tower between each segment. The tower typically has two wheels that are driven by electric motors (although hydraulic motors and even water-powered motors have been used). n Center pivots have a stationary central water supply point. The pivot continually rotates about that central point, irrigating in a circular pattern. n Linear moves typically receive a water supply (ditch or hose) along the end of a rectangular field. The linear move machines travel back and forth across the field rather than around a cen- tral point. It moves in a straight line either forward or in reverse. Because of the continuous movement across a field, the close sprinkler spacing with adequate overlap, and the use of pressure regulators on individual sprinklers, these irrigation systems can achieve high uniformities. There are numerous options for both center pivots and linear moves. The options include different tire sizes and treads, different pipe materials and pipe lining, various solutions for odd-shaped fields, sprinkler heights, sprinkler models, application rates, lengths, gear boxes, and pipeline diameters. A “standard” pivot is in the 400– 500 m length range. Linear moves may be double that length if the water supply is in the center of the machine. Center pivot, South Africa. LINEAR AND CENTER PIVOT SPRINKLERS | 203 Linear moves are inherently more complex than center pivots because the pump and control unit continually move. Assuming that the proper materials (pipe, lining, gear boxes, etc.) are specified, the primary challenges encountered with both varia- tions include: n Mobility. The tires can create large ruts (long deep wheel tracks) in the field, which interfere with tractor work and can also cause the machines to stop moving. n Infiltration problems. At the ends of center pivots the instantaneous application rate can be very high, which can cause water infiltration problems and damage to the soil structure. Infiltration problems can also be caused by poor water quality, requiring soil and/or water treatment. n Very high percentage evaporation losses in arid environments. If these machines are moved quickly, they apply a very small application that will only wet the leaves and a thin layer of the soil surface. All the water can evaporate between passes, leav- ing no water for plant transpiration. Unfortunately, it is a tendency of operators to speed up machines when they notice that an area of the field is drying up—thereby doing exactly the opposite of what they should do. n Designing very long units. For both variations, the price per hectare is lower if more area can be irrigated per machine. But long units tend to have high water application rates and more problems with their guidance systems. n Inadequate flow rate capacity. This may be a remnant of early center pivot designs in the midwestern states of the USA (where most USA pivot manufacturers are located), in which the pivots were used to supplement summer rainfall. For arid areas without summer rainfall, it is recommended to design for about 125% of peak crop ET, which allows for down time, salt leaching, unexpected hot spells, etc. n Poor sprinkler model and height selection. n Inadequate water filtration, which causes nozzles to be plugged. WHAT BENEFITS CAN THIS INNOVATION BRING? Center pivots in particular, if properly designed and managed, can provide a uniform irrigation on crops with variable soils and topography at a relatively low cost. It is easy to inject fertilizers and control the depth of water applied per week—matching ET. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Both variations are the least expensive per hectare on new developments with large fields and sandy soil. Clay loam, silt loam, and such heavy soil textures require smaller applications per pass (to avoid runoff) and consequently have higher percent evaporation losses. Both variations are also typically found on larger farms, where one operator can maintain and operate about 12 machines (or 204 | LINEAR AND CENTER PIVOT SPRINKLERS more, with remote monitoring). Although small units are common in some areas, those areas typically have very experienced irriga- tion dealerships and labor is not readily available (for pivots). Center pivots are generally operated on slopes up to 15%, whereas linear move on up to slopes of 6%. Center pivots can be equipped with a variety of options to irrigate corners, but at a relatively high cost and high complexity. They have been ideal for new developments on large fields in which a well and pump (often diesel engine-powered to eliminate the need for electrical service) can be located in the center of a field, and the circles can be configured so they “nest” among each other to increase the percentage of ground area that is irrigated. The long-term success of linear moves seems to be more of a localized matter. Over the past 4 decades, there have been many cases of linear moves being installed and then abandoned due to complexities. Alternatively, there are some regions in which rela- tively small hose-fed linear moves have become popular. Center pivots, on the other hand, tend to continue operating satisfactorily for 15–25 years in many cases. DESCRIPTION OF THE INNOVATION Center Pivot Sprinklers As seen in the image on the left, a simple center pivot has a single pipeline, in spans of 50–60 m each, with a total length of 400–500 m, that rotates in a circle. Each tower (with wheels and a gear box and motor) moves independently in short intermit- tent steps to keep in alignment with the movement of the most downstream tower. The speed is adjustable, while the flow rate is constant. Depending on the gear box ratios and the speed adjust- ment, a pivot can rotate in less than a day or once per 3–4 days. The center pivot point is set in concrete and supplies the water and electricity, while also anchoring the pivot in place. If the field is square, a simple center pivot will lose 22% of the area due to corners. The addition of end sprinkler guns can lower this loss to about 16% on a 400 m system. More complicated end units are available from all the major manufacturers, each with a different Center pivot sprinkler systems irrigating alfalfa with canal water. technology utilized to keep the end units on track. LINEAR AND CENTER PIVOT SPRINKLERS | 205 Center pivots are typically considered to have a lifespan of 15 years, but this can be much lower (5 years) if there are corrosion problems, and longer (25 years) with proper maintenance and good equipment and water quality. Major advancements have been made in sprinkler technology. The pivot manufacturers usually focus on the center pivot hardware itself and rely on a few sprinkler manufacturers for sprinkler choices. Now it is extremely rare to see spray heads or large brass rotat- ing impact sprinklers on pivots. Rather, special plastic sprinklers designed for close spacing and single rotating streams are typically used with sprinkler pressures of approximately 1.0 bar. Sprinklers are best equipped with individual pressure regulators; nozzle sizes vary along the pivot. A sprinkler at the midpoint will have, on average, half the flow rate as that of a sprinkler at the downstream end because it covers about half the area. The sprinklers near the pivot point have very small nozzles which can easily plug if the filtra- tion is insufficiently fine. 1: A center pivot with rotator sprinklers on drops that position the sprinklers at the appropriate distance above the soil or crop canopy. Weights just above the sprinklers keep them vertical in high winds. The height of the crop drop hoses can be adjusted once or twice/season as the crop grows. 2: Ruts are a serious problem in some soils. 1 2 206 | LINEAR AND CENTER PIVOT SPRINKLERS Various solutions have been developed to minimize rut problems, 1 including using raised tracks, boom-backs (sprinklers adjacent to the towers are on extensions that place the sprinklers behind the center pivot), part circle sprinklers, special tires, and even canopies that shield the towers and tires from sprinkler water. 1: Special apparatus over dual wheels to minimize soil rutting. 2: “Boom-backs” used near tower tires to minimize track ruts. 3: Special tall pivot for sugar cane. Olmos, Peru. 3 2 LINEAR AND CENTER PIVOT SPRINKLERS | 207 Center pivots can be used on mildly slop- 1 ing or rolling land, which minimizes the development cost of a project. However, runoff problems—caused by a combina- tion of large droplets, high application rates, soils with a high clay content, and poor water quality—can be serious. Some farmers use dammer-diker implements to create mini basins in the furrows (if furrows are used) to temporarily hold the water until it can infiltrate. The water must be clean enough to avoid sprinkler nozzle plugging and sand wear. Properly developed wells typically have 2 no filter of any type because there is no trash and very little sand. If there is sand from a well, a centrifugal separator (also referred to as a hydrocyclone) can be used to remove about 95% of the sand, but at the expense of an extra 0.6 bar of pressure required. Surface water is typi- cally filtered using horizontal units with perforated stainless steel filter screens, which are manually flushed. Very dirty water can require more complex filtration. 1: Furrows after a pass of a dammer-diker. 2: Eight parallel sprinkler screens for a center pivot installation. 208 | LINEAR AND CENTER PIVOT SPRINKLERS Linear Move Systems The hardware of linear move systems is for the most part identical to that found with center pivot systems. The differences are: n There are rarely any special end sprinkler units. n In theory, each sprinkler has an identical nozzle size because each sprinkler irrigates the same area. n The water inlet constantly moves rather than staying stationary. In most large systems, this means that a pump and filter need to be affixed to the linear move itself. In some smaller systems, the filtered water is supplied under pressure via a 1 pipeline/hose configuration. n A special guidance system/mechanism is needed to keep the control unit moving straight. Ditch-fed linear moves are most applicable for large fields, and the ditches are typically absolutely level. If a machine shuts off (no fuel; hits an obstruction; bogs down in a rut), the water level in the ditch will rise. There must be controls on the flow into the ditch to maintain a fairly constant ditch water depth. Ditches can be on a slope (typically on a lined ditch), but in that case the units must be equipped with a moving dam so that the water is deep enough for the filtration and pump to function properly. In that case, some water continuously spills out the end of the ditch. More extravagant systems have 2 been used over the years, including buried pipelines with automatic connections and series of level canals. 1: Small hose-fed linear move. The unit must be shut down and the hose moved several times as the linear move travels along the edge of the field. But the more complicated the equipment and operation, 2: Ditch-fed linear move. the shorter the lifespan of the systems tends to be. LINEAR AND CENTER PIVOT SPRINKLERS | 209 Manufacturers of linear moves and center pivots continue to develop innovative options. One can pur- chase towable pivots and linear moves; some linear moves can rotate in areas and then move straight in other areas. Some farmers irrigate corner areas of pivots with solid set sprinklers; others leave the corners unplanted. A variety of low pressure sprinkler packages have been developed to drop the water below the crop canopy—especially with linear moves. But the majority of systems are relatively simple. It is strongly recommended that new center pivot or linear move projects start with relatively simple equipment and management. The first objective is to be able to irrigate without encountering serious problems, and then fine tune agronomic and irrigation operations. While there are numerous sophisticated management tools that can be purchased (variable Ditch-fed linear move that supplies fields on both sides of the ditch. rate applications, GPS guidance, advanced SCADA systems, etc.), it is recommended that those be purchased in later years, after the basic operation has been successfully estab- lished. Those sophisticated tools often occupy a large amount of management attention, and insufficient attention might be paid to just making the basic equipment and irrigation management practices function well. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Highly variable costs include n Smoothing of the land surface to avoid low spots where water can pond; n Constructing the supply ditches for most linear moves; and n Bringing water into the field, and electricity for most center pivot installations. Those costs can reach $1,000–$1,500 per hectare. 210 | LINEAR AND CENTER PIVOT SPRINKLERS An installed 400 m pivot (50 ha) will cost about US$80,000, including the pump and pipeline for that single pivot. A 50 ha linear move will cost about US$100,000–US$175,000, including the ditch. A well-designed pivot or linear system on flat ground, with adequately sized pipelines (a huge factor in determining pressure re- quirement) will have a pump discharge requirement of about 30 psi (2 bars). The annual power cost depends upon the unit cost per liter of diesel or kWh of electricity, the pump efficiency, the discharge pressure, the machine flow rate, and the annual volume of water applied. Annual maintenance plus operation costs (not including power) are approximately 10% of the initial cost. The most difficult aspect of maintenance in some projects is not the cost, but rather the lack of qualified service technicians and spare parts. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Because center pivots and linear moves are mature technologies, it is worthwhile to examine competent studies of existing systems that describe problems and opportunities. One such excellent comparison study (2014) was conducted in Australia and can be found at https://www.cottoninfo.com.au/sites/default/files/documents/Centre%20Pivot%20Lateral%20Move%20Report.pdf Typically, the consulting irrigation engineer develops the specifications for the project to match the existing local conditions of soil, water, crops, and meteorology. An example of portions of such a specification can be found at www.itrc.org/reports/pivotspecs.htm SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Both linear moves and center pivots require very reliable power, and very reliable and flexible water supplies. Partly because of this, many of the major developments throughout the world have depended upon groundwater. There has been a tendency in many projects to quickly deplete the groundwater supplies. Although small units can be purchased, the strength of this form of irrigation is found in large developments with little labor re- quirements that farm large fields with single crops (although the crop is typically rotated occasionally for soil health). In short, this technology is not recommended for small fields and small landholders who each want to farm their own fields. Furthermore, small and marginal farmers will usually not have the skill set to properly maintain and manage these machines—something which is not a problem for a large development that hires permanent staff just to operate and maintain the irrigation systems. For large fields, center pivots are one of the least expensive means of irrigating. Minimal land grading is required, and the units themselves are relatively inexpensive, unless special corner units are included. LINEAR AND CENTER PIVOT SPRINKLERS | 211 SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING Because this is a mature technology, excellent equipment is widely available. Most of the large manufacturers have vast internation- al experience and can provide a complete installed package. However, they often fail to pay sufficient attention to the water supply, water quality, and filtration needs. The large manufacturers can also be weak in the final installation of the support infrastructure (wells, pipelines, valves, etc.), their expertise being in their own equipment. The following process is recommended: n Begin with an independent design done by a high-quality irrigation engineering (not civil engineering) firm that utilizes people with excellent experience with linear moves or center pivots. This firm should focus on the support infrastructure, water sup- ply/availability details, and specifications for the irrigation equipment. The firm should additionally be responsible for defining field boundaries, topography, and other design details. n Simultaneously, engage with an agronomic/irrigation firm to provide recommendations on soil amendments, rough land grad- ing, water quality amendments, and crop selection and details of growing the crops, obtaining proper tillage equipment, and so on. n Submit an RFQ (request for qualifications) to the major pivot/linear manufacturers in the international market. Provide them with the independent design work that has been completed. As part of their submittal, ask them to offer not only the details of their local partners, but also recommendations to improve the independent design work. n Select the top two from among the irrigation companies, and work with them to develop proposals. It is essential that the focus be on providing what is needed for that project, rather than simply providing the lowest initial cost. Also, emphasize the need for detailed warranties for the whole system as well as for the pivot/linear move machines. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Fertigation. Irrigation scheduling. Telemetry. PRACTICAL EXAMPLES All center pivot and linear move manufacturers have numerous examples of successful projects. 212 | LINEAR AND CENTER PIVOT SPRINKLERS LINKS Technical: A good description of center pivot factors is found in: https://extensionpublications.unl.edu/assets/pdf/ec3017.pdf Manufacturers: Valmont Industries https://www.valmont.com/ Reinke Manufacturing https://www.reinke.com/ Lindsay Irrigation https://www.lindsay.com/mea/en/irrigation/ T-L Irrigation https://tilleysprinklers.com/ 2iE International https://www.2ie.com/en/ Atlantis Muhendislik https://www.atlantismuhendislik.com/ Bauer Ges.m.b.H, Röhren-und Pumpenwerk https://www.bauer-at.com/en/product/irrigation/ Irrifrance https://www.irrifrance.com/en/ Irriland https://www.irriland.it/en/ Naras Machinery https://www.narasmakina.com/en/homepage/ BSG (former Soviet Union countries) Fregat Ukraine https://fregat.mk.ua/en/products/irrigation-solutions/ LINEAR AND CENTER PIVOT SPRINKLERS | 213 FICHE 3.13 Travelers and Hose Reel Sprinklers BRIEF DESCRIPTION OF THE INNOVATION A carriage or skid with one or more large sprinklers receives water via a flexible hose. The carriage or skid is continuously winched by a cable, or the hose is reeled in, so that the sprinkler carriage or skid moves in a straight line and irrigates a strip of ground. Once that strip is irrigated, the carriage is moved, and an adjacent strip is irrigated. WHAT BENEFITS CAN THIS INNOVATION BRING? This option provides the typical benefits of sprinkler ir- rigation, such as the ability to irrigate land that has not been precisely leveled, and with a sprinkler-controlled application rate that is independent of soil type. These units are popular on pastures and hay fields, as well as on relatively small fields that are planted with spe- cialty crops. This configuration is portable and can be removed from a field and stored in a safe, secure area. Cadman hard hose boom. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? These sprinkler systems are common for small, mobile applications. They do require a higher pressure than any other sprinkler systems, meaning either that the irrigation supply pipeline must be operated at a high pressure (about 6 atm for good sprinkler uniformity and to overcome hose friction loss) or that a portable pump must supply the pressure. Sprinklers with a high flow rate have high application rates, so they are suitable only for coarse (sandy) soils that have high intake rates. They do not work well with steep ground because of runoff problems. 214 | TRAVELERS AND HOSE REEL SPRINKLERS DESCRIPTION OF THE INNOVATION The three most common configurations are (1) soft hose single sprinkler traveler, (2) traveler with hard polyethylene hose, and (3) hard-hose reel sprinkler booms. 1. Soft Hose Single Sprinkler Traveler A wheeled carriage has both the sprinkler and a water-powered motor to drive a cable winch. It is supplied by a high-pressure, flex- ible, collapsible hose (for example, a “soft” fire hose). The cable winch pulls the unit forward in a straight line. The cable is anchored at the end of the drive path/strip. The soft hose is connected to the back of the carriage and therefore loops around toward the front. The hose must be reeled up with a (typically) separate hose reel once it is empty, and both the reel and the traveler carriage and cable must then be repositioned in the next strip to be irrigated. (This configuration has largely been replaced by travelers with a harder polyethylene hose.) Compared to the hard-hose configuration, it has three main disadvantages: a. A wider travel path is needed because the hose loop requires a strip roughly three to five meters wide, over which the loop is dragged behind the trailer/carriage, and on which a crop cannot be grown (other than pasture or alfalfa). b. The thin hose can get damaged as the loop is dragged across the ground. c. The cable and the hose must be laid out separately. The cable must be anchored to a stationary (or “deadman”) tractor at the end of the path. Advantages compared to hard hose configurations include: a. Soft hoses usually offer less friction—because of their larg- er diameter— and therefore require less pump pressure. b. They are less expensive. c. The combination of the low profile and the dragging hose tend to keep the sprinkler upright on uneven terrain. d. Once the hose has been purged of water and reeled up, the components are easier to move around than the larger, heavier, and taller hard-hose units. Hydro soft hose single sprinkler traveler. TRAVELERS AND HOSE REEL SPRINKLERS | 215 1 2. Traveler with Hard Polyethylene Hose A single sprinkler is mounted on a small, wheeled stand at the downstream end of a hose. A separate drive unit and hose reel are positioned at the end of the field, toward which the hose reel continually pulls the sprinkler. The complete unit is then towed to the next strip with a tractor. The hose is unreeled, the sprinkler is positioned at the end of a straight path, the unit is pressurized, and the process is repeated. This is much easier to reposition than the soft-hose units, and there is no loop in the supply hose. The large hard-hose reels, which stay stationary while irrigating, are rotated with either water motors or external diesel or gasoline engines. The water motors, however, create a pressure loss, which necessitates higher pump pressure. The main disadvantages of both the hard and soft hose single sprinkler units are: 2 a. High application rates compared to other sprinkler methods. b. Very high pressure requirements—at least double or triple 1: Hard hose reel for those of drip microsystems (if both are properly designed). single sprinkler, with buried water supply c. Poor distribution uniformities of water in high winds. pipe. 2: Bauer Rainstar traveler with hard hose. d. Significant edge effects—especially at the beginning and end of a strip of land that is irrigated. Single sprinkler units are very susceptible to poor design, yielding pressures that are too low, or spacing that is too wide. The large sprinklers typically require pressures of roughly 6 atm for proper stream breakup (to reduce droplet sizes and to provide good distribution uniformity). The friction loss in a properly sized hose may be 2 atm. Farmers also often purchase small hoses to minimize the initial purchase price, but the friction (and hence pressure drop) in a smaller hose can easily be two to three times that of a properly sized hose. To further save money, farmers often purchase pumps that are too small and do not provide enough pressure. The overall result of low sprinkler pressures tends to be runoff, damage to seedbeds, and poor irrigation efficiencies. 216 | TRAVELERS AND HOSE REEL SPRINKLERS 3. Hard Hose Reeled Sprinkler Booms 1 The popularity of these is regional, as opposed to the hard-hose travellers, which can be found throughout the world. Like the hard-hose travellers, these use hose pulling/reeling as a move- ment mechanism, but instead of a large single sprinkler, they have a boom with numerous small sprinklers. This is somewhat like a small linear-move sprinkler machine, but with a completely differ- ent mechanism for movement. Sprinkler booms must be used on flat fields because, in an uneven field, the low booms would hit the ground. The advantages of the sprinkler booms are (i) lower pressure requirement than single sprinklers, (ii) less wind interference, and (iii) lower instantaneous application rates. A major disadvantage is that they are much more difficult to re-position for subsequent irrigation sets (passes). They are also not as adaptable to irregu- larly shaped fields as are the single sprinkler units. Both types of booom sprinkler systems—fixed boom and rotating boom—are found in different areas of the world, with fixed boom being most common. 1: Bauer hard hose reeled sprinkler boom. 2: OCMIS hard hose boom. 2 TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Costs per unit of area are heavily dependent on field sizes and field configurations, as well as the availability of a water supply. A medium-sized, hard-hose unit plus pump will irrigate roughly 18 ha in an arid environment if it is moved twice a day on a four-day rotation. The initial cost—sprinkler, hose, reel, pump, and supply pipeline—is approximately US$2,000/ha. With an energy cost of US$0.25/kWh, the annual power cost works out to about US$108/ha. Labor is roughly four person-hours a day. A tractor is needed for moving the unit twice a day. TRAVELERS AND HOSE REEL SPRINKLERS | 217 TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS n ISO 8224-1:2003 Traveller Irrigation Machines—Part 1: Operational 1 Characteristics and Laboratory and Field Test Methods n ISO 8224-2:1991 Traveller Irrigation Machines—Part 2: Softwall Hose and Couplings—Test Methods n ISO 8224-1:2003 / AMD 1:2011 Traveller Irrigation Machines—Part 1: Operational Characteristics and Laboratory and Field Test Methods—Amendment 1 n ISO/WD 8224-1 Traveller Irrigation Machines—Part 1: Operational Characteristics and Laboratory and Field Test Methods (currently under development) SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS The high-energy consumption of single-sprinkler units makes them unsuitable for large fields unless there is a special situation, such as vandalism, or easy access to canal water along one side of the field. Small units can be ideal for small fields because of their flexibility, especially in rainfed areas that need only supplemental irrigation. 2 SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING The different configurations all require occasional maintenance, which in turn requires a local support network of technicians, training courses, and spare parts. Because they can be so energy-intensive, it is best to assess the total annualized cost (an annual initial cost plus annual operating cost) of various options before purchasing. Additionally, because of their high application rates—and therefore potential for surface runoff and resultant damage to the surface soil structure—a soil scientist or agronomist should also be consulted about the maximum permis- sible application rates. 1: Southern Cross soft hose traveler. 2: DuCaR soft hose carriage. 218 | TRAVELERS AND HOSE REEL SPRINKLERS “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY High-efficiency pumps, specifications for pumps and pipelines, filtration. PRACTICAL EXAMPLES All the major manufacturers have ample examples of applications. It is highly recommended that existing applications, with similar crops and soils, be visited before purchasing or specifying these units. LINKS Soft hose single sprinkler travelers: Southern Cross Industries (South Africa) http://southx.co.za/ Hydro Engineering (USA) www.hydro-eng.com/irrigation/products BTS Engineering (Ukraine) https://bts.net.ua/eng/irrigation-watering-systems/irrigation-machines/ DuCaR Irrigation (Australia) http://www.ducarsprinklers.com.au/irricruiser-ultimate-soft-hose-travelling-irrigator Hard hose reeled single sprinklers (travelers): Bauer GmbH (Austria) https://www.bauer-at.com/en/products/irrigation/rainstar Kifco (USA) https://kifco.com/en-us/ourproducts/water-reels.aspx Irrigabras (Brazil) https://en.irrigabras.com.br/carretel-irrigador Hard hose reeled sprinkler booms: Bauer GmbH (Austria) www.bauer-at.com/en/products/irrigation/irrigation-booms ABI (USA) https://www.abi-irrigation.com/product/falcon-irrigation-booms/ OCMIS (Italy) https://www.ocmis-irrigazione.it/en/spray-booms/40-m-spray-boom Cadman Power https://cadmanpower.com/irrigation/booms.html TRAVELERS AND HOSE REEL SPRINKLERS | 219 FICHE 3.14 Drip/Micro Irrigation BRIEF DESCRIPTION OF THE INNOVATION Drip and other micro (drip/micro) irrigation systems begin with a reservoir or flexible water supply pump and filter station, from which water flows throughout a field via a piped network, ending with rows of hoses that ex- tend to every plant in a field. The hoses have emission devices that apply water locally to plants—either in the form of a “drip” or with a small rotating (micro-sprinkler) or fixed above-ground spray (micro-sprayer). In some regions, for example, Israel and California, the industry has matured after more than 40 years of implementation. In those regions almost all the land devoted to certain crops—almonds, pistachios, citrus, wine grapes, pep- pers, processing tomatoes—is now irrigated with some form of drip/micro. The specific form of drip/micro used depends largely upon the crop, the soil, and the technological capability of the farmers. While there are many successful above-ground systems that have been in use for more than 20 years, these systems can fail catastrophically if the design, management and/or support infrastructure are poor. The most common reasons for failure are an inadequate flow rate; inadequate soil wetted area; poor germination of row crops; emitter plugging (blockage); salinity buildup in the soil; damage by insects, animals, or birds; root intrusion; and physical failure of pipes, fittings, and tubing. Nevertheless, in California, for example, there has been rigorous field documentation of excellent field uniformity and maintenance, proving that a properly designed, installed, and maintained drip/micro system will provide better uniformity of water distribution throughout a field than any other irrigation system. However, the uniformity of an improperly specified, designed, installed, and maintained drip/micro system will often be no better—and possibly worse—than that of an average sprinkler system. Success is therefore achieved by having excellent design standards, working with certified designers, procuring excellent equip- ment, and having well-trained and educated farmers. High levels of performance require an adequate maintenance budget; qualified professionals who understand maintenance and chemical treatment and fertigation (application of fertilizer through the 220 | DRIP/MICRO IRRIGATION irrigation water); and a first-rate private irrigation dealership network. That combi- nation is often unavailable in many areas of the world and cannot be established during the short period for which international projects are typically funded. In areas where successful drip/micro irrigation and the necessary support infra- structure are not already well established, investment must focus on simplicity and making things function properly with good equipment and maintenance. Complex technologies and programs—including automatic valves, computerized irrigation scheduling, automatic fertigation, using soil or plant monitoring programs for any- thing beyond providing general information, drone technology, and so on—should 1 not be incorporated into project investment because the level of sophistication they require is often lacking and can, perhaps, be achieved only later. 2 The two valid “automatic” features that should be incorporated into most drip/ micro systems are automatic backflushing of filters, and some form of automatic pressure control. As examples, pressure control might involve the use of automatic pressure regulators at each entrance to a block of hoses, or the use of pressure- compensating emitters. Buried drip systems of any type (where the emitters are below ground) should be avoided. Although there is ample literature about these systems, they require special tillage equipment and more sophistication than can be expected to be successfully used on a development project. Furthermore, numerous unpredict- able problems may be experienced, such as root pinching of the hoses, soil back siphonage into emitters, root intrusion into emitters, gophers, wireworms, inad- equate expansion of the water into the root zone, and difficulties in establishing a wet area around transplants or seeds. Buried systems are also more expensive than above-ground systems. 1: Automatic block pressure regulator for drip. 2: Shallow-buried drip tape with lay-flat manifold. One pressure regulator for every three tapes. Solid-set portable sprinkler system for early irrigation of lettuce and salt leaching. 3: Three rows of drip tape, slightly buried, on onions. 3 DRIP/MICRO IRRIGATION | 221 WHAT BENEFITS CAN THIS INNOVATION BRING? The success of drip/micro irrigation systems depends not only upon their design and management, but also on the crop. Some crops usually provide an excellent response/benefit, but others may be marginal. Almonds, pistachios, peppers, processing toma- toes, strawberries, wine grapes, sugar cane, onions, and broccoli have tended to have much better quality and yield with properly designed and maintained drip/micro systems. In some cases, yields have doubled—even on farms that already had good irrigation practices. However, other crops, such as alfalfa (which requires buried drip), table grapes, cotton, and some types of lettuce have not always demonstrated notable success as compared to results with other well-designed irrigation systems. Although drip/micro systems have been used on almost every imaginable crop, it is not recommended that investments be made in those systems for grain, pasture, and other crops that are not planted in rows. Reported increases in crop yields are best understood in context and must always be compared against the historical base. It is not difficult, regardless of the type of new irrigation system employed, to double crop yields if the initial yields were already very low— assuming the new irrigation system is properly designed and managed. Typically, with drip/micro, the yield increases occur in part because farmers simultaneously introduce other improved farming techniques, such as better fertilization. Water savings are frequently listed as a major benefit. But there is no escaping the fact that a well irrigated, unstressed crop will have higher evapotranspiration (ET) rates than one that is stressed and with poor growth throughout the field. Gross water applied to a field may be reduced with drip/micro (assuming the farmer practices good irrigation scheduling), but at basin level the water consumption may actually increase. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Drip/micro irrigation investments can be very feasible and profitable as long as certain optimizing conditions hold—if water is avail- able with good flexibility; if there is excellent filtration of the water; if the details of the system match the crop requirements; if the design and installation were excellent and the farmer understands maintenance; if the system is not too complex; and if there are no problems such as rabbits, foxes, and rodents that destroy the hoses. If any of these requirements is not met—decisively and comprehensively—there is a good chance of failure. Drip/micro can excel (compared to other irrigation methods) in orchards and vineyards with variable soils and hilly topography. Although drip irrigation can maintain a relatively wet root zone, it is incapable of leaching salt from the complete wetted root zone. This is achieved only with adequate effective rainfall, or by occasional leaching with sprinklers that are temporarily brought in for salinity management (annually with field crops, once every 5–10 years with vineyards and orchards). 222 | DRIP/MICRO IRRIGATION DESCRIPTION OF THE INNOVATION Although the original drip irrigation method was largely sold based on claims of water savings and improved yields, many of the first installations used drip irrigation because it was the least expensive way to irrigate orchards on hilly ground. The original design idea was to use a hose with small, regularly spaced outlets (emitters). The small outlets would emit water at very low flow rates (for example, 2–4 liters/hour), which meant that hoses could have small diameters and the cost would be lower than that of larger hoses with higher flow rates. These original systems were permanently installed and required labor only for routine maintenance. Over the last 40 years, the quality of equipment has dramatically improved— partly as a result of trial-and-error, and partly due to a maturing competitive industry responding to consumer demand. Various forms of micro sprayers (which do not rotate) and micro sprinklers (which do rotate) were developed to provide an expanded root zone for trees and table grapes. Drip emitters with lower flow rates, improved hydraulics, and less plugging (clogging) sensitivity became commonplace. While micro sprinkler and micro sprayer connections need to be physically inserted into hoses in the field, most emitters are now “in-line”, meaning they are built into the hose/tape during the manufacturing process at a desired spacing. 1 Drip tape (thin-walled hose with built-in emitter pathways) was first used on vegetables and strawberries, but quickly expanded to sugar cane in the 2 1970s. Its use and development stagnated for about 15 years, until a new generation of drip tapes emerged with much better quality and emitter designs. Since about 2012, the most successful innovation has been the widespread availability of pressure-compensating (PC) emitters that deliver a precise flow rate regardless of changes in pressure caused by uneven topography and friction in hose and pipes. PC emitters provide the same discharge flow rate once some threshold pressure is reached. This threshold pressure used to be about 0.8 bars but now is as low as 0.25 bars. The result is that excel- lent new-system (before plugging occurs) distribution uniformities can be 1: Surface drip tape being installed on lettuce. The lettuce was transplanted and started with sprinklers. 2: Surface drip achieved throughout a field with relatively low pressures, without a complex tape being retrieved from a strawberry field for disposal after hydraulic design. one season. DRIP/MICRO IRRIGATION | 223 The tremendous spectrum of options in hardware, emitter design, emitter spacing, and filtration is the result of both “market-pull” forces of innovation and “technology-push” forces of innovation at work. In part, much the way automakers respond to customer preferences, demands, and trends, there are market pressures to continuously produce “the latest and greatest” emitter design, whether or not it is actually better than the previous year’s. But there are also genuine technological and engineering improvements by manufacturers working hard to meet the huge range of agronomic requirements. No two crops are the same. Irrigating a row of trees requires a different emitter design than irrigating a row of lettuce. And while a citrus tree’s leaves may extend down to the ground surface, an almond tree’s leaves will remain at least 60 cm above the ground surface—meaning that a micro sprinkler pattern will extend further out with almonds than with citrus. Water from boreholes and wells may have no silt but might have sand and iron bacteria problems. Therefore, the filtration requirements of well water are typically quite different from those of canal water, which has sediment and algae. In short, one size does not fit all. Once the idea is made to invest in drip/micro, it is essential that experts be consulted who are not tied to just one brand of equipment, but who have broad experience with different types of filtration, emitter designs, valves, crops, climates, and soils. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Average initial costs for a good commercial scale drip/micro system are roughly US$5,000 per hectare. This assumes that water is available on a flexible basis, and that no regulating reservoirs must be constructed on-farm. It also assumes that there is a depend- able electricity supply with a service connection where the pump will be located. Anything larger than a few hectares will require three-phase electricity or and engine-powered pump. At the lower cost range, there are small drip systems for vegetable gardens that consist of a raised tank, simple filtration and dis- posable drip tape. These systems have been around for at least 40 years; they are labor intensive (because of the need to carry water to the tank, lift the water up, and refill it frequently), but can be effective for home plots. The lack of good filtration and chemi- cal maintenance programs will contribute to emitter plugging, so the inexpensive tape needs to be replaced seasonally or every couple of years. These may cost only US$100 for a small home garden. Annual maintenance and operation costs are highly dependent upon the quality of the irrigation system that was purchased and the quality of the water. A good design will incorporate excellent filtration that can be easily backflushed, and a chemical injection sys- tem that can be used to minimize emitter plugging due to minerals or bacteria. The hoses and regulators will be properly designed to provide good flushing at the ends of hoses or tapes. The key is to have good equipment that supports preventive maintenance. If the plan is to unplug emitters as they clog, that plan is doomed to failure. 224 | DRIP/MICRO IRRIGATION The cost of power clearly depends upon the local cost per kilowatt-hour (kWh) of electricity or diesel. Costs also depend upon the pump efficiency and the required pump pressure. A typical pump discharge pressure for these often incorrectly named “low pressure” systems is 3.5 bars. It is possible to design an excellent system on a 10–20 ha field with a pump discharge pressure as low as 2.0 bars, but to accomplish this the designers need to be highly competent and be able to select the correct filters and emitters. Although excellent pumps are available worldwide, ending up with the right system for a given 1 field depends upon having skilled designers with the capability and authorization to select the proper pumps—not just accepting the lowest bid. If electric pumps are used, it is essential that there be adequate electrical utility grid coverage, and that the electricity be reliable (free from frequent blackouts) and of good quality (stable voltage that is consistently in the correct range). Solar installations are a special case that can have benefits for relatively small fields. They are only recommended for flat fields with non-PC emitters. Beyond fertilizer, additional annual expenses include water quality treatments. Controlling bacteria populations is essential and is typically accomplished by injecting chlorine (continuous or intermit- 2 tently) into water while paying proper attention to pH control—which in practice means injecting acid and chlorine simultaneously but using different injection ports in the irrigation pipeline. 3 Water infiltration problems due to poor water quality sometimes require the addition of soluble gypsum to the water, or special attention to fertilizer mixes, and/or acidification to remove car- bonates and bicarbonates from the water. Proper application of these chemicals requires not only purchasing the chemicals, but also paying more sophisticated workers or companies to provide the service. In many projects, this is neglected and the drip/micro performance quickly degrades after a few years of good results. 1: Simple punch plate (perforated metal) prefiltration screen upstream of regular filters. 2: Rotating suction screen in a canal for pre-filtration. Media tanks for final filtration. Engine with booster pump. All portable for leased land. 3: Media tank filtration station with injection ports, large tanks for major fertilizers (light blue or aqua color), small barrels on right (blue) for special chemicals, silo for pure gypsum storage, and gypsum mixing 4 machine (white). 4: Disc filters; all pipes are polyethylene. DRIP/MICRO IRRIGATION | 225 TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Worldwide, standards and specifications for drip/micro systems are often lacking. There are abundant standard testing procedures regarding “emission uniformity” of new, individual emitters, and standards are available for the manufacturing of components such as PVC pipelines, hoses, filters and such. Those are all helpful but insufficient, because the performance of an irrigation system depends upon how all the components work together. For example, an excellent hose, made of the proper resin, carbon black mix, and so on, will not provide good irrigation results if the hose diameter is too small for the flow rate, and length and slope. 1 Furthermore, there are no rigorous standards for very important details, such as how many drip hoses should be provided for each tree row, and what the emitter spacing and emitter flow rate should be. The answers to these questions are more a matter of agronomy than hydraulics. For example, 30 years ago most trees were drip irrigated with three or four emitters per tree, with a single hose per tree row. Now one sometimes sees as many as three hoses per row, with each hose having six emitters per tree. Similarly, growers may use micro-sprinklers to obtain the desir- able percentage of soil that is wet. Wine grapes may do quite well with one or two emitters per vine, but table grapes may need micro-sprayers that wet a larger soil surface area to achieve excellent quality. 1: Micro-sprinkler on almonds—one per tree. 2: Micro-sprayers on almonds—two per tree. 3: Double line drip on almonds. 3 2 226 | DRIP/MICRO IRRIGATION The following practices have proven successful: 1. Establishing an excellent designer certification program. The Irrigation Association in the USA has such a program, begun in 1981. 2. Creating consumer demand for high quality by developing and advertising a “Drip/Micro Irrigation Consumer Bill of Rights” that consists of questions addressed together by every farmer and vendor to customize the drip/micro system to match local requirements. See: http://www.itrc.org/reports/icbrdripmicro.htm https://www.youtube.com/watch?v=SLhf5QGZ7HI 3. Using minimum standards for drip/micro systems for grant programs. An example is the EQIP program of the Natural Resource Conservation Service of the US Dept. of Agriculture in the USA. Conservation Practice Standard—Microirrigation Code 441. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Drip/micro systems have provided excellent economic benefits in many situations. They have also been oversold in many situations, with disappointing results. These systems require much more purchasing and operational sophistication than traditional surface irrigation. Drip/micro is most successful when it fits into a complete system that includes n Quality control at all levels of design, installation and management of the irrigation system itself; n Reliable and flexible water availability; n Fairly high-value crops (as opposed to grains and pasture, for example); n Good processing, storage and market facilities for specialty crops; n Strong irrigation dealerships with adequate inventory of equipment; and n The availability of professional agronomic support services, such as fertilizer mixes, fertigation equipment, insect control, and so on. In short, simply installing a drip/micro irrigation system will not guarantee agronomic or economic success. Another factor that distorts people’s understanding of drip/micro irrigation systems is the unfortunate tendency, in the development literature, to refer to very low-priced drip/micro systems as if they were examples of today’s modern systems. One extreme example is the “bucket kit.” This is comprised of a simple water bucket suspended from a pole or tripod or other elevating device, and some DRIP/MICRO IRRIGATION | 227 drip tape running from the bucket. Bucket kits are obviously cheap, have no filtration or pump, and are only good for a small garden and for a short time. They cannot be defined as modern drip/micro irrigation systems. On one level above that extreme end—but not that far above it—are the many development projects that do not adequately invest in good equipment; proper filtration; training; standards; chemical injection; PVC pipe of the proper strength; good pressure regu- lation; hoses of sufficient wall thickness; ensuring that water is available on a flexible and dependable schedule; establishing a reliable electric grid; and so on. Such investments are unsustainable and likewise cannot be described as modern drip/micro irriga- tion systems. But they are cheap—often less than half the outlay of US$5,000 per hectare mentioned earlier. Farmers beginning with drip/micro very seldom know what they need or what the options are. Therefore, it is essential that a project invest in developing the required private industry expertise (and extension personnel) to support drip/micro system investments. The fact that in dozens of countries around the world this rarely happens is typically a political problem. Another frequent challenge arises from the fact that production agriculture can be quite different from research station agriculture. This is notably apparent when responsibility for training devolves to academics who have little experience or familiarity with options for production agriculture using drip/micro. As noted above, for large-scale success of drip/micro, the water delivery service must be reliable and flexible. Often the govern- ment irrigation agencies cannot provide that service, necessitating additional investment in numerous regulating reservoirs or reliance on well pumps. On the environmental side, assuming that drip/micro is successful on a large scale, there will be a reduction in return flows. Some zones in some irrigation projects depend upon return flows as a water source. The rerouting of fresh water flows may be required to meet agronomic and urban requirements in those zones, as well as maintenance of environmental flows in drains. High quality equipment is now available globally. Development proj- ects that fund local inventions of drip/micro are typically destined to Large on-farm reservoir needed for a drip system served by inflexible canal deliveries. 228 | DRIP/MICRO IRRIGATION fail. The biggest challenge in development projects is to find or develop the local expertise and support infrastructure in order to obtain good results. Although international experts can provide guidance in the proper design and maintenance, everything must be obtainable and sustainable locally once the project begins. This human element, and the critical part it plays, is often neglected because of an overemphasis on the financial bottom line, an overdeveloped belief in the role of the hardware, and overblown expectations of potential benefits. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING As emphasized above, proper training, certification, and development of standards must have already occurred before construction starts. Furthermore, experts are needed before design to select the appropriate irrigation systems or options with drip/micro. One aspect of a standard is to require proof of a certain performance level. With drip/micro, this includes the requirement that the system DU (distribution uniformity) be better than 0.90, as an example. But the specific procedure to be used for evaluating the system DU in the design procedure must be defined, and the penalty for not meeting that specific number must be defined and enforced. Field evaluation procedures can be found at http://www.itrc.org/classes/iseclass.htm. The correct options for design/procurement/servicing will depend upon the context. It is often not fully appreciated that in the European, North American, and Israeli drip/micro environments, a support infrastructure—effective marketing, careful crop process- ing, transportation networks, irrigation dealerships, robust electric grids, rigorous quality control procedures, and so on—already existed before drip/micro was introduced. The transition to the complex management and design of drip/micro systems was there- fore relatively simple (though not entirely without challenges). Additionally, in these regions, improvements to processes and quality control are continually made. Furthermore, in those areas, almost all of the development was done by private farmers and compa- nies—albeit often with government cost sharing and, in some cases, government technical support. In contrast, investments sponsored by international donor agencies target a very different environment, and accordingly require a very different approach. Numerous variations have been attempted. In India, for instance, Jain Irrigation developed a model in which it would provide the irrigation design, support the irrigation system development, and sell the irrigation equipment, but also help with agronomic advice. Furthermore, it processed and marketed the crops. This was heavily subsidized by the government, and has had some economic sustainability challenges recently. In a contrasting example, in about 2013, near Olmos, Peru, the government provided water to large areas of virgin desert land, then leased large parcels (several thousand hectares each) to private sugar cane farmers to produce cane for either sugar or ethanol, over a period of several years. The private farming organizations, for their part, installed an extensive, integrated infrastructure of roads, schools, major pipeline networks, on-farm irrigation systems, sugar mills, and so on. When the lease expires, ownership of DRIP/MICRO IRRIGATION | 229 everything will revert to the Peruvian government. Meanwhile, working within the framework of a limited-time lease, the private farm- ing companies have a high incentive to quickly and economically develop the complete irrigation, crop, and support infrastructure. In Guatemala, a successful model has been developed by a private company (www.topke.com) that designs, installs, operates, and maintains drip/micro systems on a contract basis with farmers. In California, some irrigation dealerships have adopted a similar model by designing, installing, operating, and maintaining the drip/micro systems on behalf of farmers on a contract basis. There are also a few companies that provide all the fertigation equipment at no charge—in exchange for being the exclusive sellers of all the fertilizers to the farmers. Those companies have the expertise to provide the correct fertilizer mixes and even remotely monitor and control the injection of those fertilizers. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Fertigation (application of fertilizers through irrigation systems); variable speed drives; high efficiency motors and pumps. PRACTICAL EXAMPLES This is no longer an emerging technology—it matured in the 1970s. LINKS Technical: Drip and Micro Irrigation Design and Management for Trees, Vines and Field Crops, 5th Ed.. 2016. 420 pg. Available free of charge in PDF format at www.itrc.org/books/index.html Manufacturers: There are numerous excellent manufacturers of emitters, filters, hose, valves, etc. that can be discovered with a web search. The following are only a few examples. Jain www.jains.com/ Netafim https://www.netafim.com/ Rivulis http://rivulis.com/ Bowsmith https://www.bowsmith.com Toro https://www.toro.com/en/agriculture FERTIGATION 230 | DRIP/MICRO IRRIGATION FICHE 3.15 Fertigation BRIEF DESCRIPTION OF THE INNOVATION Fertigation is the application of fertilizers through irrigation water. It has been used for decades with all irrigation systems (drip/micro, surface, and sprinkler). It was typically used as a convenient means of occasionally apply- ing nitrogen fertilizer. More recently, it has become more sophisticated—with new forms of fertilizer, complete fertilizer mixes, spoon-feeding of fertilizers, and improved chemical injection hardware. Good irrigation design and management can provide substantial benefits, such as more efficient irrigation, greater crop yields, and improved crop quality. Fertigation can augment these benefits. The distribution uniformity (DU) of fertilizer throughout a field can only be as good as the DU of the irrigation water. Hence, the benefits of fertigation de- pend on the quality of the design and management of the irrigation system. WHAT BENEFITS CAN THIS INNOVATION BRING? Fertigation through an excellent irrigation system allows farmers to develop fertilizer application schedules that closely match the fertilizer uptake rates of plants as they grow, as opposed to applying fertilizer only once or twice during the growing season. A proportional injector. This is especially important for nitrogen fertilizers, because nitrogen moves with soil water. Hence, the traditional, large, occasional nitrogen applications are often inefficient due to leaching losses throughout the growing season. With fertigation, fertilizers can be applied even after lay-by (the growth stage beyond which tractors can no longer enter a field). This avoids the fuel consumption, crop damage, and additional soil compaction problems that occur with tractor-applied fertilization. FERTIGATION | 231 HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Chemical injections of acid, chlorine, and so on are system maintenance requirements of efficient, modern drip/micro systems. The same types of injection equipment can be used for fertigation. With annual crops, phosphorus and potassium fertilizers are commonly applied to the soil and mixed into the soil during plowing and discing. Those two fertilizer types do not move substantially with the water, so the large seasonal soil applications can be effec- tive. With drip/micro of trees and vines, however, such ground-applied fertilizer will not move into the root zone without rainfall. In other words, fertigation is typically essential for drip/micro irrigation on trees and vines. Traditional surface irrigation systems often have poor irrigation efficiencies and distribution uniformities (DUs). Therefore, although it is relatively easy to inject fertilizers into surface irrigation water, the results are often less than spectacular. Sprinkler and drip/micro systems are ideal for spoon-feeding fertilizers. These irrigation systems can be designed to give good DUs. It is important to mind certain issues, such as possible corrosion of aluminum sprinkler equipment by copper compounds, but good awareness programs can minimize problems. In general, wherever efficient and uniform irrigation systems are found, there is usually enough sophistication to have a successful fertigation program. Farmers typically begin with nitrogen fertilizer applications. With experience, they advance in sophistication to fine-tune the scheduling of the applications and the selecting of the correct nitrogen mix for different growth stages—for example, urea versus ammonium nitrate versus calcium nitrate, and so on. The next advance in fertigation sophistication is to in- clude more micronutrients and supplemental potassium and phosphorus. This is a gradual transition that is best not rushed by new practitioners. Neatly arranged chemical tanks behind drip filters. Each tank has a separate chemical injector. Chemical supply tanks connect to a fitting on a well-labeled board outside the fence and fertilizer dealers fill the tanks with the right chemicals. 232 | FERTIGATION DESCRIPTION OF THE INNOVATION Besides a good irrigation system, successful fertigation requires ad- dressing a number of other issues for maximum benefit, in particular: n The irrigation water quality; n The types of fertilizers that are available; n The injection equipment; n The crop fertilizer requirements of the crop, and fertilizer’s interactions with the soil; and n The correct dosages and timing of various fertilizer applications. Knowledge Proprietary commercial, proportional fertigation system with remote Almost all these aspects are beyond the knowledge of most small control encased in a box. The company provides the box/injectors at no charge but sells the chemicals and the fertigation scheduling and farmers. Therefore, for those farmers there must be a qualified dosage advice. knowledge base among fertilizer suppliers and extension personnel who can provide simple and pragmatic advice on how to succeed with local conditions and crops. The small farmers need “1-2-3 step guidelines” they can follow without needing to understand all the theory behind what they are doing. Large farmers, on the other hand, often have employees and the financial means and experience to quickly adopt sophisticated equipment and practices. Water Quality Irrigation water quality is important to understand, because different fertilizers can have adverse reactions with certain qualities of water. As an example, if anhydrous ammonia (ammonia gas) is injected into water that has high magnesium or calcium concentra- tions and a high pH (very common in some arid regions), a large percentage of the ammonia will volatilize and be lost. Likewise, many phosphorus fertilizers will precipitate in water with high magnesium or calcium concentrations. These examples illustrate why small farmers need to know which fertilizers will work in their area, and which will not. Fertilizer Types In some areas, fertigation was widely adopted when there was a shift from solid to liquid fertilizers. Fertilizer dealers in many areas almost exclusively sell liquid fertilizers and send out truck/trailer units to refill farmers’ fertilizer tanks. In areas without access to liquid fertilizers, farmers must dissolve the solid fertilizers before injecting. Some solid fertilizer compounds do not dissolve well; FERTIGATION | 233 others have additives that do not dissolve at all; and the solubility rates further depend on the individual fertilizer and temperature. Special agitator-based mix- ing equipment often has to be used for the fertilizer mix to improve solubility. In short, having only solid fertilizers available makes fertigation more complex and difficult. Techniques There are numerous fertilizer injection techniques. It is advised to begin modestly, with simple injections and simple fertilizer mixes. Simplicity can be achieved by dripping fertilizer into the source water—for example, upstream of the booster pumps of a drip irrigation system, or into canals with furrow irriga- 1 tion—or with a venturi injector that is plumbed around a booster pump. Neither of these requires an independent engine or motor. There are also many high- 2 quality electric and gasoline engine-driven fertilizer pumps. For situations in which many fields with different crops and different owners share a common water supply, it is often necessary to have trailers with fertilizer tanks and portable (engine-driven) fertilizer pumps that will inject into just one field at a time. But for large fields with a single crop, the tendency is to inject everything at the irrigation pump station. Open top 3 4 Motor Non-pressurized tank Lower pressure High pressure Chemical 1: Mixing tank and injector for flow Float valve box solid fertilizers. 2 & 3: Utilization Mainline flow of a float valve to drip fertilizer into a canal or open pipe at a Irrigation pump constant rate, even as the tank empties. 4: Correct configuration Into canal or open pipe of a venturi injector. The irrigation pump provides the pressure Water Chemical differential required by the + water Injection device which venturi to create a suction on the needs water forced Chemical inlet through it chemical inlet line. 234 | FERTIGATION Electrical pulsating valve on chemical line Venturi injector Visual (non-electronic) chemical flow meter Pressure regulator 1 Chemical feed line (pressurized in this case) 1: Arrays of fertilizer pumps pressurize the fertilizer, which is then distributed via pipelines to fields kilometers distant. Each fertilizer formulation is conveyed by a single pipeline that has its own pump. 2 2: Proportional injector for center pivot fertigation. FERTIGATION | 235 As sophistication and abilities grow, farmers often move on to more complex fertigation programs that use different injectors for each different fertilizer and with correspondingly different injection rates. In some areas, automatic proportional injection—with which the rate of chemical injection automatically varies with the irrigation system flow rate—is well established. This level of sophis- tication is strongly discouraged for projects where farmers, suppliers and the logistics/support chain have not yet matured. There are numerous variations of fertigation schemes. In large commercial developments, such as large sugarcane plantations, companies may have a centralized, solid fertilizer mixing plant where fertilizer solutions are created, along with an independent network of pipelines that extend for many kilometers, each pipeline carrying a different fertilizer. Each fertilizer pipeline will have an outlet at, for example, every center-pivot sprinkler location. The control of the injection rate and type of fertilizer is done inde- pendently at each center pivot. Although this design eliminates the need to transport fertilizer to tanks at each field, the fertilizer pumping system is complex. A program of timing and dosages of various fertilizers is typically developed at the beginning of the irrigation season, and adjusted occasionally based on soil and crop monitoring results. Small farmers usually lack the sophistication and budget to develop good, continuous soil (crop-nutrient) analysis. As a result, they depend on either the fertilizer dealer or agricultural extension agents for seasonal recommendations. The capacity of dealers and extension agents therefore needs to be developed. Soil–fertilizer interactions are often complex. Phosphorus and potassium fertilizers have very little movement in the soil. For field crops, it is therefore often best to physically incorporate these fertilizers into the soil before the growing season, then supplement them throughout the crop season through fertigation as needed. Nitrogen compounds are the simplest to inject via fertigation, but they undergo many microbiological transformations in the soil, between urea, nitrate, and ammonium—all of which affect how quickly they are available for plant uptake and how deep they move into the soil. Again, small farmers do not need to know the technical details— they just need specific recommendations on what to use, how much, and when. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Costs for injection systems vary from US$10 to US$1,500 per hectare, depending on the sophistication of the hardware and the availability of liquid fertilizers. The more sophisticated and expensive the system, the greater the risk and annual maintenance expenses. Fertilizer costs are highly variable depending upon the region, energy prices, and sophistication of the fertilizer manufacturing industry. But with a good fertigation program, the improvements in crop yield and crop quality will typically outweigh the costs. 236 | FERTIGATION Range of costs for injection hardware only, not including fertilizer, mixing of solids, fertilizer tanks, nor enclosures/buildings Complexity Description $US Least Liquid fertilizer is dripped into an open water source at a constant rate 100 One venturi injector plumbed around an irrigation booster pump 450 One venturi injector plumbed around an irrigation booster pump, with an automatic volume limitation 850 apparatus on the fertilizer tank Electric pump with appropriate backflow prevention features on the irrigation and chemical lines and 6,000 electrical panel Injection of seven different chemicals using proportional injectors, flow meters, backflow prevention Most 50,000 features, and proper injection ports TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Fertigation involves a system of hardware, management, and chemicals, and therefore can be complex. A fertilizer injector (a piece of equipment) is not a fertigation program/system. For success, local experts are needed who can distill the potential complexities and choices into successful pragmatic packages that are simple for farmers to understand. Components and aspects to consider include: n Types of fertilizers to use n Rates of fertilizer injection n Compatibility of different fertilizers n Crop fertilizer requirements—pre-planting, during the season, and post-harvest n Backflow and personal safety hardware and procedures n Chemical injection equipment n Power supply for injection equipment n Equipment and processes for converting solids to liquids n Timing of fertilizer injection during the irrigation cycle—accounting for the irrigation method and characteristics FERTIGATION | 237 n Distribution uniformity (DU) of the irrigation system n Chemical requirements other than fertilizers—such as acids, chlorine, pesticides. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Most farmers will readily identify a good irrigation system as worth investing in, but the value of good fertigation is not as well un- derstood. Chemistry can easily be perceived as a mystery. Fertilizer is often seen by small farmers as a burdensome expense rather than a shrewd investment. The widespread adoption of fertigation by farmers will therefore need a support infrastructure of well- trained extension personnel and fertilizer dealers. In many cases, neither the extension personnel nor the fertilizer salespersons have the knowledge and experience to provide sound advice regarding the equipment and techniques of fertigation. Therefore, there must be a program to increase their expertise. Simple nitrogen fertigation programs are almost always successful and are therefore widely implemented. They are fairly inex- pensive, may use simple formulations (such as UAN-32) that have no chemical interaction problems, and are almost always more effective than traditional fertilizer practices—regardless of the type or value of the crop. Automatic low pressure cutoff Electric Irrigation pipeline motor and SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, pump Flow meter CONTRACTING, AND SERVICING Vacuum relief Irrigation pump panel valve Large, commercial companies typically have the sophistication to Check valve Control panels adopt complex fertigation injection programs, but those installa- electrically interlocked Automatic tions are not suitable for small farmers. Small farmers must start low pressure drain Injection tank with excellent but simple fertigation programs and equipment Drain line Agitator that are robust and will provide obvious benefits. Over time, as Injection (if dry fertilizer used) and automatic they see success, they will desire to advance to more sophisti- check valve Electrical conduit Panel for injector pump and agitator cated applications, but they will need technical support for this. Chemical discharge line Injection pump Filter prior to injector pump “MATCHING” INNOVATIONS—OFTEN EMPLOYED Connections for fresh water SIMULTANEOUSLY hose to flush out chemicals Chemical flow meter Injection hose Chemigation uses the same equipment and practices as ferti- gation, but expands on it to include drip system maintenance Chemigation system with United States Environmental Protection Agency chemicals, fumigants, and insecticides. (USEPA)-required safety equipment for pesticide injection with well water. 238 | FERTIGATION LINKS Technical manuals: Burt et al. 2018. Fertigation, 2nd Edition. Cal Poly ITRC. http://www.itrc.org/books/fertigation.php (Also available in Spanish.) Carlos Cadahia Lopez. 1998. Fertirrigacion—Cultivos Hortícolas, Frutales y Ornamentales. Ediciones Mundi-Prensa. Additionally, Netafim provides fertigation advice for individual crops. An example is https://www.netafimusa.com/bynder/175A1572-CB71-4CB4-A53734F4E140DC8C-irrigation-and-fertigation-for-corn.pdf For general information on using fertilizers: FAO. 1984. Fertilizer and Plant Nutrition Guide. http://www.fao.org/3/aq355e/aq355e.pdf Reetz, Jr., H.F. 2016. Fertilizers and Their Efficient Use. International Fertilizer Association. https://www.fertilizer.org/wp-content/ uploads/2023/01/2016_ifa_reetz.pdf Injection Equipment: Mazzei Injector Company https://mazzei.net Netafim fertilizer injectors https://www.netafimusa.com/bynder/710A1F6B-6FFC-475D-B04D892CCC4F281B-a009-fertilizer- injectors.pdf ITC Dosing Pumps https://www.itc.es Milton Roy® https://www.miltonroy.com H.E. Anderson Company https://heanderson.com Amiad® Water Systems https://amiad.com pH Technologies, LLC https://www.phtechllc.com Hort Americas https://hortamericas.com FERTIGATION | 239 FICHE 3.16 Soil and Plant Water Status and Irrigation Scheduling BRIEF DESCRIPTION OF THE INNOVATION A large toolkit exists for evaluating soil water and plant stress, as well as for properly scheduling irrigation events. Soil moisture measurement tools such as gypsum blocks and tensiometers have been widely available commercially for more than 60 years, and numerous government awareness programs have promoted the use of these and more recent tools. Similarly, numerous commercial and university irrigation-scheduling programs that use data on crop evapotranspiration (ET) rates have been available for agricultural use for more than 50 years. Most farmers with modern irrigation systems use a combination of tools to properly schedule field irrigation—some of which may involve sensors. The automation of irrigation valves based on field sensors is a completely different case. While the irrigation scheduling literature has discussed such automation of field irrigation valves, and commercial companies have steadily promoted their use, this technolo- gy remains primarily in the research arena. The promotion of such practices should be avoided in international development efforts. In short, sensors can be very helpful. Wise irrigation scheduling is very helpful. Moving to automation in the field triggered by soil or plant sensor readings is unwise. WHAT BENEFITS CAN THIS INNOVATION BRING? Many benefits—environmental, energy, crop quantity/quality—can be achieved through good irrigation management, irrigation scheduling being just one component of such management. But to achieve precise and effective irrigation scheduling, there are several irrigation management prerequisites, including the following: n A uniform distribution of irrigation water across the field—quantified as Distribution Uniformity, Low Quarter (or DUlq).1 n Flow rate plus volumetric measurements of water applied to all fields. 1 As described in Burt, C.M., A.J. Clemmens, T.S. Strelkoff, K. Solomon, R.D. Bliesner, L.A. Hardy, T.A. Howell, and D.E. Eisenhauer. 1997. “Irrigation Performance Measures—Efficiency and Uniformity.” Journal of Irrigation and Drainage Engineering 123, no. 6 (November): 423–442. https://doi.org/10.1061/ (ASCE)0733-9437(1997)123:6(423) 240 | SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING n A manageable water supply that can be applied to a field in a controlled, flexible manner to meet on-farm irrigation scheduling needs. n Excellent management of historical records of the volumes of water applied at various crop growth stages and to which ir- rigated areas, plus observations of yields, benefits, and problems. n Careful examination of historical records in order to learn lessons and improve processes. Government efforts to fund irrigation scheduling programs, and to promote the use of soil/plant water sensors, would do well to take the following observations into consideration: n It has been said that irrigation management becomes simpler in a person’s mind the further they are from the field. Many, if not most, government programs to provide farmers with sophisticated soil and plant moisture sensors and with digitalized evapo- transpiration data have tended to be accompanied more by high levels of anticipation in the minds of the program proponents than by actual success in the field. The record appears to show that government investment in these innovations does not align strongly with farmers’ own practical experience with attempting to implement them for more than a short period. n Throughout much of the world, farmers have little or no control over when water arrives at their fields, nor the flow rate when it does arrive. Under these conditions, programs to improve field irrigation scheduling by farmers end up as lost investments. Investments such as land smoothing, land leveling, and gated pipe could be more beneficial in situations such as this. Teaching farmers how to properly schedule irrigations misses the mark when in reality they have no control over such scheduling. n Good irrigation scheduling will generally result in reduced water application to a field—though not always. If one considers that most sensors indicate a level of stress, and modern irrigation scheduling is intended to reduce that stress, it follows that well-scheduled irrigations will be more frequent than they were historically. Any effort to save water with more and smaller irrigations will therefore require modification of the irrigation system and water supply. n There is tremendous 3D spatial variability from field to field in terms of soil type, amount of water received by individual crops, and crop vigor. Even in a well-managed field, there will typically be a 50 percent difference spatially in soil moisture (specifi- cally, the area around each plant) and crop vigor throughout the field. This is easily verified by examining satellite imagery or automated yield-measurement records from crop-harvesting equipment. In most cases, such measurements serve primarily as educational and awareness tools, because the measurement values will vary if the sensors are moved even a few centimeters. n Soil and plant water status devices typically indicate a level of water deficit or stress. That provides an indication of when water is needed. It is an entirely different matter to determine how much water to apply, and how to control its application. n Successful farmers know that they cannot rely exclusively on remote monitoring and sensors. They need to physically visit fields daily to check for diseases and insects, irrigation problems, weak spots in crop growth, and so on. SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING | 241 n Having data about plant or soil water status is only one piece of the irrigation scheduling puzzle. The schedules must take account of a range of practical issues, such as labor schedules and tractor cultivation. Additionally, at various periods during their growing season, many plants—including cotton, wine grapes, processing tomatoes, and stone-fruit trees—require delib- erate stress (deliberate “under-watering”). Irrigation may need to be terminated early to enhance crop maturation. Terminating irrigation to generate this deliberate stress is not a question that digitalized data about plant and soil water status can answer for farmers. They need to be on the field to inspect the crop in person. Furthermore, the different irrigation methods create different limitations. It would likely be impossible to apply a small water depth of 5 cm uniformly to furrows, even if that might be desirable from a crop irrigation stress standpoint. To take a different example: Portable (hand move) grid sprinklers typically operate on a labor schedule with a rotation through the field of perhaps 10 days. The irrigation scheduling question for such systems is basic: When the 10-day rotation is completed, should the next cycle begin immediately, or should it be delayed several days? Alfalfa needs to be harvested and hay needs to sit in the field for several days to dry. Such considerations are not typically built into computer scheduling models. These are just a few of the considerations of practical agricultural irrigation scheduling. In summary, although soil water and plant water stress measurements of any type can provide very valuable input for decisions on proper irrigation scheduling on fields (for instance, determining when and how much water to apply), proper irrigation scheduling is much more complicated than that. It must fit into a complete picture encompassing crop, irrigation method, tillage, labor, and soil system. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Monitoring soil and plant water status is not an innovation. Neither is good field irrigation scheduling. Recent innovations have been in the development of tools—or system components—that can be used to serve a successful irrigation scheduling program. Automatic actuation of irrigation valves based on soil water sensors has been physically possible for at least 40 years with com- mercially available equipment. Similarly, the remote monitoring of sensors and valve movement has been physically possible for a good while and is a relatively mature process, although it is still continually improving. Access to remote-sensing images of crop vigor and evapotranspiration (ET) is also improving. Database management of telemetry information is possible. But none of these components equates to—or can be substituted for—a complete and robust irrigation scheduling program. The feasibility of irrigating automatically based on a feedback loop using soil or plant sensors also depends entirely on having a wa- ter reservoir supply at the field level, because neither wells nor canals, on a large scale, can provide the needed frequent shifts in flow rate. Its feasibility also depends on having a permanent solid-set irrigation system (solid-set permanent sprinklers, or drip/micro systems). In summary, automatic irrigation of fields based on soil and plant water status should not become a focus of a develop- ment agency. There are larger and more fundamental problems to solve related to irrigation water management. 242 | SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING With landscape or garden irrigation, some type of automatic ET-based scheduling is indeed common and effective. But that situation is quite different from agriculture. With landscape or garden irrigation, automatic valve controllers are commonplace. The irrigation systems are solid-set and permanent. Water is available on demand. Homeowners are not especially worried about quality and yield. And most homeowners rarely adjust the settings on their automatic controllers. Manufacturers have therefore developed a wide range of landscape or home irrigation controllers that use recent or historical local ET data to adjust the duration of each irrigation set throughout the season. Compared to not making any weather-based control- ler adjustments at all, this is certainly a laudable improvement, but that still does not make it applicable or suitable for meeting the practical needs of automatic irrigation at the agricultural field level. DESCRIPTION OF THE INNOVATION As noted earlier, soil and plant water measuring has existed for many years. So has good irrigation scheduling. The available tools have improved over time. The following components or tools have a track record of supporting successful irrigation scheduling. Soil Augers and Probes Most successful farmers and irrigation schedulers make extensive use of hand probes of various designs. Soil samples from various depths are extracted by hand, and the soil moisture deficit is estimated using the traditional “feel” method. Heavier soils have a very distinctly different feel depending on the soil moisture content. The moisture contents of sandier soils are more difficult to accu- rately assess. For fields that have many rocks, or crops with deep root zones (trees and vines), the use of hand augers and probes is more limited, but it is very common with most row and field crops (although a variety of different sensors are used). Soil Moisture Sensors These devices typically produce one of two types of measurement: 1. Soil moisture tension. This indicates how strongly water is held in the soil, which in turn indicates how easily it might move into the roots. Typical sensors include various forms of gypsum/matrix blocks and tensiometers. 2. Soil moisture content. This gives an idea of the percentage of moisture in the soil, but by itself does not tell how easily the water can move into the roots. Some devices inserted in vertical tubes (permanently or temporarily) can provide mea- surements of soil moisture content at various depths, and in a narrow radius of about 10–15 cm around the tube. Most soil moisture-content sensors now are individually placed at specific points (depth and horizontal distance from a plant or a dripper). SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING | 243 The most popular soil moisture sensor today measures the soil’s (electri- cal) capacitance. Some models are able to detect soil water salinity. The capacitance meters have wires extending to the soil surface, where a reading can be obtained periodically or continuously by means of a datalogger. All soil moisture sensors measure only an extremely small sample area, with specific 3D values. Two sensors that are almost identically situated will typically give different readings—sometimes major differences. Sensor readings are highly dependent on the installation procedures. Although manufacturers will provide various claims of accuracy, the variability in readings from one sensor to another in the field, due to the location of the sensor and its installation techniques, means that absolute sensor accuracy is in practice not an important issue. Often, what matters more is Accurate soil moisture measurement in a nonrepresentative relative changes in moisture values from one day to the next, not what the site, but with excellent road access. California, USA. absolute values are. However, graphs of soil moisture over time can be excellent awareness tools. Deep soil moisture sensors will continue to dry if the location is deficit-irrigated. The periodic return of soil moisture to field capacity after an irrigation will indicate that the irrigation wa- ter has infiltrated at least as deep as the sensor. For drip/micro irrigation on permanent crops, good irrigation scheduling programs usually schedule irrigations based on ET estimates, and then install soil moisture sensors near the outer edges of the wetted soil pattern. If the soil tends to dry out over time, more water is applied. Plant Stress Indicators For many decades, some irrigation schedulers have used either leaf bombs (pressure chambers or infrared thermometers to obtain a reading, with the intent of not allowing the plant stress to exceed some maximum value). The values obtained by these devices vary with time of day, and by the location of the sample leaves on the plant. Excellent equipment is available for this, but the correct techniques must be used (see, for example, https://fruitsandnuts.ucanr.edu/pressure_chamber/). Some crops, such as white and red wine grapes, cotton, and almonds, have well-established leaf water potential thresholds for different growth stages. Recently, there has been interest in measuring sap flow in plants. Tree trunks, for example, expand and contract over a 24-hour cycle in a manner that indicates the rate of evapotranspiration. Although good measurement equipment is available, good threshold numbers for critical values have yet to be established. This remains a research item. but the research is expensive, and it tends to shy away from the $64,000 question: just how representative of an entire orchard can a single tree be? 244 | SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING Visual Crop Indicators Most successful modern irrigation managers have learned to read specific visual indicators of the plants they grow. A plant may need to be irrigated when it develops a purple hue by 2:00 pm, for example. The ratio of cotton squares to cotton flowers can indicate the presence or absence of stress, as can the expansion of tendrils of grape vines. Satellite and Drone Imagery 1 This can be used as an important management tool. There are three levels of imagery: 2 n Google Earth and similar images. These are very helpful in locating weak growth throughout a field. n Satellite and drone images processed for the NDVI (normalized dif- ference vegetation index). Each image pixel is assigned a numerical value to indicate the strength of vegetation. The relationship between the NDVI values and crop ET rates has been widely debated, with very poor correlations noted in some cases. Nevertheless, this technique can be used to quantify different levels of growth throughout a field and throughout a season. n Satellite and drone images processed for ET. This is more complex than NDVI computations because more wavelengths are measured, and the data processing must include local weather station data for a computation of ETo (the reference ET). The lack of high-quality hourly weather data is a frequent problem. There are two common mathemati- cal techniques (SEBAL and METRIC), each of which has many variations. 3 Google is developing a worldwide-accessible database that will provide this information. The SEBAL and METRIC computations, done by dif- 1: Weather station situated without proper ground cover or upwind fetch. Chile. 2: Weather station ferent groups, commonly have results with differences of more than 10 with reasonably good surroundings. Oregon, USA. percent. They have been most widely used to determine basin water 3: Weather station with no ground cover or upwind balance ET values. crop. Olmos, Peru. SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING | 245 Crop Coefficients (Kc) and Reference ET (ETo) The use of crop coefficients and ETo has been the industry standard for field irrigation scheduling since the early 1970s. The Food and Agriculture Organization of the United Nations (FAO) and the American Society of Civil Engineers have produced excellent references on the details of this subject. The fundamental equation for calculating historical crop ET is Crop ET = Kc x ETo where Kc depends on the crop type, its stage of growth, root zone stress, and the moisture content of the soil and plant leaf sur- faces. Although we have “basal” crop coefficients (Kcb) that provide a value for no stress and a dry soil surface, at each stage of growth, the actual Kc must be determined locally. Furthermore, the desirable Kc may be less than a higher value that the plant could potentially have—such is the case when a crop needs to be stressed. The ETo was originally described as the transpiration of a well-watered grass crop with a dry surface. It is best computed with hourly weather data of temperature, solar radiation, relative humidity, and wind run. The data must be collected from a local, properly sited weather station that is well maintained and has excellent instrumentation. In many areas of the world, it is difficult to find such weather stations. Irrigation Scheduling Software Such software can be purchased or downloaded at no cost from numerous sources. There are large variations in how informa- tion is input—all manual vs. automatic download of weather data vs. automatic download from telemetry vs. mixed methods—what computations are made, and what outputs are available. Some commercial software is tied to specific field hardware, such as center pivots or a certain brand of sensor. But almost all the software involves a combination of weather information, crop coefficients, and computations of a soil water balance. The following sample list of software illustrates the variability: n Compare Smart Irrigation Software https://www.g2.com/categories/smart-irrigation?order=popular&page=2#product-list n Valley Scheduling https://www.valleyirrigation.com/scheduling n Four scheduling tools under improvement by the Ogallala Water CAP team https://ogallalawater.org/irrigation-scheduling-tools n The Wisconsin Irrigation Scheduling Program (WISP) https://fyi.extension.wisc.edu/cropirrigation/ wisconsin-irrigation-scheduling-program-wisp n A new web-based irrigation scheduling tool that is part of the North Dakota Agricultural Weather (NDAWN) website https:// www.ag.ndsu.edu/waterquality/documents/web-based-irrigation-scheduler n Pulse™ Scheduling Software by Irricheck https://www.irricheck.co.za n Hortau Irrigation Scheduling Software https://hortau.com/irrigationscheduling 246 | SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING Irrigation Scheduling and Local Expertise and Customs When academics, researchers, and government officials talk about irrigation scheduling, there is often an implicit understanding that the farmers will apply the proper depth of irrigation water (meaning a volume of water over a field area) at the proper times. But many traditional farmers are not even familiar with depth terms such as “10 cm of water.” Nor are they familiar with volumetric terms such as hectare-meters (ha-m) of water. They may not even be familiar with flow rates such as liters per second (lps) or cubic meters per second (CMS). Their knowledge may be limited to knowing that their ditch needs to be full and water needs to arrive at least once every two weeks. This is not to say that attempts to improve irrigation scheduling have no merits; it means that a program must be pragmatic and approached at the pace of the learning of the program’s recipients—the farmers themselves—with movement to the next more complex level only after the benefits of the current step have been shown on farm, and the farmers are convinced of it. Developing an Irrigation Scheduling Program with the Components As noted earlier, successful irrigation programs have notable prerequisites—specifically, a flexible water supply, flow and volume measurements, good distribution uniformities of irrigation water to plants throughout a field, and an ability to develop, maintain, and analyze historical records. Once those are in place, most good programs use the approach of Crop ET = Kc x ETo to make an estimate of daily crop ET over the most recent period, and then make an estimate of the ET for the immediate future (perhaps the next week). The ET computation is then combined with field records and observations to determine how dry the soil is, whether irrigation is needed, and if so, how much. That knowledge is further combined with an understanding of the limitations of the irrigation system, labor, tillage, and so on. The result is a schedule of irrigation timing and duration for each field for the future week. Certainly, no government agency has such intimate knowledge of the irrigation system, labor situation, tillage program, stage of growth, and allowable stress level of every field and farm under its jurisdiction. Inevitably, then, well-meaning but one-size-fits-all attempts by government agencies to give an entire region of farmers all the details of irrigation scheduling they need have not achieved success. By contrast, programs have been successful by first establishing the prerequisites of successful irrigation scheduling, and then demonstrating to farmers how various tools might be used to implement it. The tools must be affordable, reliable, and available commercially and locally. Disseminating web-based or newsletter information that simply provides daily local ETo values can be a major first step in the learning process. SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING | 247 The discussion above is primarily oriented toward irrigation projects that have many small farmers. Large private agricultural devel- opments of thousands of hectares can often harness the resources to quickly implement a modern irrigation scheduling program. TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION The primary costs are n Establishing a good network of local, complete, properly sited, well-main- tained weather stations. Initial costs are about US$35,000 per station, with maintenance approximately US$3,000 per year per station. n Establishment of communications, plus quality control of field equipment and data, plus computerized databases and computations of ETo, plus distribution of that information, at a cost of US$250,000 initially, plus Soil moisture measurement site, as required by a US$100,000 per year for operation and maintenance (O&M). regulatory agency. The site is not representative of growing crop conditions. California, USA. n Training of agricultural extension personnel in the practical details of irrigation scheduling techniques and equipment. This would depend on the size of the project. Such training would require all the tools mentioned above, the establishment of hypothetical irrigation schedules for various conditions, discussions with farmers about what they are capable of and willing to do, and so on. No dollar estimate is given here because the variables are numerous: it depends on the size of the program, the level of local expertise, the need for transportation, and so on. n Implementation of programs in the field, including working with farmers on the complete process, installation of various sen- sors, and so on. This again depends on the size of the program, level of local expertise, and the variety of crops and irrigation methods. The sensors themselves are relatively inexpensive compared to the human investment needed. For example, a typical capacitance meter for measuring soil moisture, including a datalogger, costs US$100–500, depending on the options selected. An excellent hand soil auger with a tee handle and four-foot extension bar currently costs about US$300–500. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS The 40-year-old California Irrigation Management Information System (CIMIS) program, operated by the California Department of Water Resources, has a large network of weather stations, quality-control procedures, computation techniques for determining ETo, and information distribution. It also has standards and guidelines for the complete program. 248 | SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING Individual sensor manufacturers typically provide guarantees of accuracy and adherence to various standards, but their field appli- cation references should always be thoroughly checked. As discussed above, a successful program requires an excellent understanding of the participating farmers, irrigation systems, crop growth characteristics, and periods of crop growth that require crop-maturation water stress. There are no lab or textbook standards for this, although excellent extension service publications are available for a wide range of crops. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS Good irrigation scheduling usually provides the following benefits: n Better crop growth and crop quality n Application of water volumes that closely match the crop’s actual water requirements (minus rainfall), which result in n Reduced deep percolation of water and nutrients and pesticides; n Lower pumping bills; and n Reduced water bills for fields (assuming there are volumetric charges). SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING The previous sections sought to show that an irrigation scheduling program for a project with many small farmers cannot be pur- chased as one would purchase a piece of equipment such as a tractor. It is relatively easy for large developments with center pivots and only one or two crops such as corn (maize) or small grains to implement a good irrigation scheduling program. Rather, with multiple small farmers, a successful program entails a long-term investment and patient learning curve. This involves, first, under- standing the farmers’ worldview and knowledge base, ensuring that the prerequisites of irrigation scheduling are well in place, and then motivating the farmers through a well-structured outreach, educational training, and awareness-raising program that provides them with practical information on techniques, timing, do’s and don’ts, and effective hardware. LINKS Irrigation Consumer Bill of Rights for Soil and Plant Sensors: http://www.itrc.org/reports/icbrmonitoring.htm SOIL AND PLANT WATER STATUS AND IRRIGATION SCHEDULING | 249 FICHE 3.17 Telemetry with Focus on On-farm Systems BRIEF DESCRIPTION OF THE INNOVATION Telemetry, also known as SCADA, or Supervisory Control and Data Acquisition, assumes many forms—from simple remote monitor- ing to complex remote automation. Most on-farm telemetry systems are relatively simple remote-monitoring systems. Simple remote monitoring is a one-way flow of information, typically from a sensor of sorts in the field to an office screen or to someone’s smartphone. By contrast, remote automation is a two-way flow of information supported by redundancy, advanced communications, complex office algorithms, local programmable logic controllers (PLCs), automatic data storage and backup, and much more intricate user interfaces. The repeated use of the word “complex” is deliberate, to emphasize that these systems can be complicated and often require a completely new set of skills for implementation, use, and repair. SCADA can be applicable in situations with manageable (controllable) resources such as water and with superb technical support. SCADA is just one tool to support the complex management of advanced irrigation systems. It is extensively and successfully used in (i) canal operation; (ii) pump operation (for bulk water supply as well as on-farm well pumps), (iii) weather station data transmission, and (iv) field-sensor readings. To be effective, SCADA systems require: n An excellent SCADA plan and specifications. n Specialized technicians (often referred to as “integrators”) who can successfully install the specified hardware and software. n Adequate initial and annual maintenance budgets (approximately 15 percent of initial costs per year). n Qualified technicians who are long-term employees and can provide frequent and annual maintenance, upgrading, and cali- bration of equipment. n Immediate availability of spare equipment and parts. Remote soil moisture monitoring in a field of processing tomatoes. 250 | TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS Excellent equipment and software are commercially available. The potential problem areas are all the requirements listed above. The rupture of a single link in the chain can render a SCADA system inoperable. Most on-farm telemetry systems are relatively simple monitoring systems and are available as complete commercial packages; service agreements can be obtained from single vendors. WHAT BENEFITS CAN THIS INNOVATION BRING? At the simplest level (remote monitoring), a well-designed and maintained SCADA system can provide real-time information on the status of individual sensors across a wide spatial range. The information can be digital (for example, whether a pump is on or off) or analog (for example, the actual water level in a reservoir or the moisture content at a particular point in a field). Real-time availability of data, and the archiving of that data, can in many cases pro- vide digitized historical records (databases), unbiased information, and verification of scheduled field activities. It can save travel time and allow managers to make deci- sions based on actual conditions. Simple remote-monitoring systems, if designed and maintained properly, provide rich information and serve as decision-support systems. Typical on-farm telemetry systems are simple and provide only monitoring, which in turn provides only information. How the information is made available to users, whether users want or need that information, and how that information is harnessed is what ultimately determines the benefits that are attained. At the on-farm level, there are numerous companies that for many decades have sold various automated irrigation packages that utilize SCADA systems as a component. But these packages are typically much less complicated than those for a complete irrigation project (branching canals, pipelines, pump stations and outlets). It is rare for farms to have the need for the more sophisticated systems, or to have the technical Cell phone used for remote monitoring by the expertise to support them. On-farm automation of anything but very simple irrigation person in the center of the image. functions usually provides few or no benefits. Some SCADA irrigation systems incorporate security cameras capable of detecting vandalism and unauthorized entry into key sites by transmitting images via high-speed, high-quality radios. TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS | 251 HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? The feasibility of SCADA largely depends on two factors: 1. The complexity of the system. Remote monitoring of relatively simple sensors—such as sensors found in weather stations, water level masurement devices, or simple on/off sensors of pumps—can be packaged in simple, comparatively inexpensive systems that require relatively low maintenance. A SCADA system should always begin with simple remote monitoring as the starting point of a learning curve. By contrast, systems of higher complexity can—and do—go wrong in many more ways. 2. The support systems surrounding the SCADA—the long-term availability of qualified personnel, an adequate budget, attention to detail and neatness, and so on. Successful SCADA systems require almost fanatical attention to detail, organization, and consistency. Conversely, over the years, the following factors have tended to point toward failure: 1. Labor costs in that area are low, so effective manual moni- toring and operation could have been less expensive than purchasing and operating a SCADA system. But there was an unjustified assumption that if things could be automated (either automatic data collection or automatic movement of canal gates) things would be much easier. In general, if an organization cannot properly organize and mobilize humans to do tasks, SCADA equipment purchases will not solve the problems. SCADA can provide timelier, 24-hour information/ operation, but key organizational skills must first be in place. 2. Irrigation offices were (and continue to be) disorganized and unkempt—excellent office management is one cornerstone of a well-functioning SCADA system. 3. Existing electrical equipment (gate actuators, pumps, and so on) had exposed wires, inadequate maintenance, and messy installations. This frequently led to inoperable equipment. Remote monitoring of flow through an irrigation district turnout. This 4. Young engineers and electronics technicians have short became a failed example of attempting to remotely monitor many sensors tenures—they remain in their positions only for a few years. with a very inexpensive system. 252 | TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS 5. The needs for data, and exactly how they will be used, were not carefully defined in advance. 6. Although there was a budget to purchase and install equipment, there was no well-defined, guaranteed budget for long-term maintenance and support. 7. A detailed, comprehensive SCADA plan was not developed prior to any purchases. 8. Technicians did not make the first SCADA packages work properly at the workshop or the office, before attempting to deploy them in the field. 9. The SCADA system’s benefits were oversold, with inadequate attention paid to the large amount of ongoing work that would be necessary to properly maintain it. A core component of SCADA is the communications system. Currently, the options for this in many regions can be limited because of factors such as government restrictions on radio frequencies, limited or unreliable mobile data service, and mountainous topog- raphy. Data connectivity will undoubtedly improve in the future as better private satellite communications become available, but such communications will generally require annual subscription fees. DESCRIPTION OF THE INNOVATION Overview of some SCADA/Telemetry variations Frequency of data transmission to Case Basic function Frequency of sensor monitoring office or mobile users Alarms for digital readings—such 1 – Monitor only Continuous Only if the alarm condition exists as high/low values Alarm for analog readings—such As often as once per second, as 2 – Monitor only Only if the alarm condition exists as height, position, temperature seldom as once every 15 minutes For river basins, often a few times per Monitoring of analog readings, but As often as once per millisecond, 3 – Monitor only day. For irrigation projects (canals, no alarms as seldom as once per 15 minutes pipelines), often once per minute Once per day remote monitoring As above (once per millisecond to 4 – Monitor Cases (2) + (3) that can be overridden by an alarm once every 15 minutes) exception at any time TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS | 253 Frequency of data transmission to Case Basic function Frequency of sensor monitoring office or mobile users Remote monitoring of analog values plus alarming, plus both Once every 30 seconds to once every 5 – Monitor plus remote and on-site control of 5 minutes. Anything less frequent Once per millisecond to once per manual remote actuators, pumps, and so forth, than once a minute is outdated and second control with additional remote control cumbersome for operators, and may not functions that include two-way detect problems quickly enough communications Once every 30 seconds to once every Case (5) plus ability to remotely 6 – Monitor plus 5 minutes. Anything less frequent change target values for individual Once per millisecond to once per local remote than once a minute is outdated and sites, for local independent second automation cumbersome for operators, and may not automation (such as a pump) detect problems quickly enough A wide array of simple commercial monitoring packages for on-farm irrigation are available in some countries, with adequate local support. These very simple packages are usually relatively inexpensive (initially), and it would be unusual for farmers to even know about a SCADA plan, let alone invest in one. Such packages typically include: n Installation of sensors of one brand n Transmission of the data—typically via cell phones or spread-spectrum radios—to a web connection n A company-based central data storage and information distribution center n Data availability for visual graphs and tables, or for downloading via the web 1 2 n Ongoing maintenance contract (optional). 1: A large-screen tablet provides a small, portable user display and interface (without a keyboard and mouse). Image source: Google Images. 2: Remote pump monitoring assembly. 254 | TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS Such simple commercial packages are typically purchased for the following applications: n Monitoring of soil and plant conditions via sensors n Monitoring of well-pumping status and perhaps flow rate or volume n Private weather stations purchased by large farmers n Center-pivot systems, for which manufacturer-supplied packages will include some remote-control features. Typically, on-farm monitoring packages do not include a farm base station. Rather, all the monitoring data are automatically collected by the commercial company that sold the system. That company then organizes the data graphically and/or in tabular form and makes them available via the internet to anyone who has the password. Because these packages rarely include automation, the risk of inadequate operation remains low. The companies that supply these packages are often tempted to display their data- 1 handling skills by organizing the purchaser’s data in dazzling ways, suggesting numerous applications for the sensors and data, and presenting it all on graphically impressive screens. Quite often, however, this amounts to information overload for farmers, who only use a very limited percentage of the data. For very large irrigation farm projects, SCADA/telemetry packages are typically more sophisticated and expensive, but also prone to failure owing to excess complexity, inadequate maintenance, the lack of trained long-term technicians, and the lack of an advance SCADA plan for how information will be organized, distributed, and used. Irrigation project SCADA/telemetry packages should therefore always proceed through an evolutionary process that starts at no higher a level than Case (4) as defined in the table above, then progresses to Case (5) and eventually to Case (6). A successful process involves much more than making a list of materials and objectives and signing a simple contract. Success is heavily dependent on quality and commit- ment of personnel, proper planning, gradual sequential development, a process of learning and making mid-course corrections, and adequate budget at the local level, especially for maintenance. 1: Monitoring and control package on a center pivot. 2: Proprietary white cabinet 2 containing fertigation pumps, PLC, control valves, and communications equipment. Note the multiple injectors and sensors on the blue irrigation discharge pipe. TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS | 255 TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Costs vary widely depending on the options selected and the availability, quality and pricing of local internet service and com- munications options. An internet search such as “farm soil moisture monitoring” will generate the names of many companies willing to provide quotes for different options. Some companies provide websites where farmers can “build and configure” a system and immediately see how much it will cost or receive a pricing quote by email. An example is https://www.onsetcomp.com/ hobonet-configurator#. A single datalogger plus cellular plan, solar panel, mounting tripod, and four soil sensors currently cost about US$2,500, plus tax and installation and maintenance (but excluding the service to collect the data and send it to the customer). For big farms with more complex needs, the cost of a SCADA system can easily exceed US$1 million. A good base station currently costs roughly US$120,000. The price of an individual site will vary from approximately US$5,000 to US$50,000, depending on func- tions and features. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS A description of what one can expect to find in a large SCADA system plan is available at www.itrc.org/. SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS It is beyond dispute that high-quality, real-time information—collected from a wide spatial region and then organized, archived, and properly distributed—can be very helpful in managing water systems in an optimum manner. Because water systems have great influence on the environment, the society, and the economy, the benefits are far-reaching. But this does not mean the expenditure needs to be high. Farmers typically use only a fraction of the information that SCADA systems can make available via a remote-mon- itoring system, so complex does not necessarily mean better. Furthermore, without good support and maintenance, high investment in a sophisticated system can be in vain. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING, AND SERVICING Simple Systems Even very simple farm monitoring plans still require knowledge of what options to purchase, and the installation of sensors must be done properly. Often, this expertise is available from the vendor. It is always advisable to obtain a list of the vendor’s current cus- tomers, and to speak with those customers before making a purchase. 256 | TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS Complex monitoring and automation The SCADA systems that have office base stations and more complex monitoring and automation capabilities have completely dif- ferent design, procurement and servicing requirements. Here, it is necessary to use a systems approach that includes appropriate planning, personnel, budget, and gradual implementation, and the essential development of local expertise. Having a SCADA plan developed by a competent third-party consultant is essential. The local expertise issue involves who will develop the plans, who will install and commission the system, and who will operate and maintain it. Even in highly developed irrigation projects, the issue of personnel is a persistent challenge. It is difficult to find compe- tent individuals and companies in this sector. If there are competent local SCADA service providers (integrators), some projects contract out all the installation, servicing, and maintenance to them. Other projects do everything in-house because the local contractors may change personnel frequently, be too expensive, or have slow response times. Between these two extremes, the picture is often a mixed one. But this question of long-term, competent personnel for on-going support needs to be resolved before contracting begins. “MATCHING” INNOVATIONS—OFTEN EMPLOYED SIMULTANEOUSLY Improved flow measurement and control; automation of pumps and variable-frequency-drive (VFD) controllers; improved irrigation scheduling using information from automated weather stations. PRACTICAL EXAMPLES In more developed areas of the world, there are thousands of successful, small-scale, soil-monitoring SCADA systems, and an internet search will bring up the names of several manufacturers who provide them. Pump-monitoring programs are more localized and have been widespread in certain areas, such as California, where electricity companies subsidize the monitoring packages. Weather station monitoring has been available for more than 40 years. Examples of larger, on-farm SCADA systems can best be found by contacting center-pivot manufacturers such as Valmont or Lindsay. One novel example of a center-pivot irrigation project, the Navajo Indian Irrigation Project (NIIP), initiated by the Navajo Agricultural Products Industry (NAPI) in New Mexico, USA, even includes the GPS locations of all support personnel. A job position advertisement for a Control Center Operator technician in that project provides insight into the features of SCADA: https://napi. navajopride.com/wp-content/uploads/2020/05/Control-Center-Operator.pdf TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS | 257 LINKS Examples of simple monitoring packages (not endorsements): https://www.mywildeye.com/soil-moisture-monitoring https://www.onsetcomp.com/hobonet-configurator# https://www.scientificsales.com/6345CS-Leaf-Soil-Moisture-Temperature-Station-p/6345cs.htm https://www.campbellsci.com/weather-eto-stations https://stevenswater.com TILE DRAINAGE 258 | TELEMETRY WITH FOCUS ON ON-FARM SYSTEMS FICHE 3.18 Tile Drainage BRIEF DESCRIPTION OF THE INNOVATION Tile drains—called “tile” because they used to be made of ceramic tiles of fired clay—are pipes buried underground at depths of 1–2 meters, to drain away sub-surface water from a field in order to allow enough air space in the soil for proper cultivation. Excess water from the surrounding soil flows into the pipes, which are declined at a slope, through perforations in the pipe wall. Pipes are typically thin-walled corrugated polyethylene these days instead of ceramic tile. By lowering a high water table, tile drains increase the depth of the crop root zone and ensure good aeration. Removing this high water also removes salt—creating a healthy crop root zone. Tile drainage systems have been in use worldwide for more than 150 years. Measuring how high the water table is: Netherlands-based engineers led most of the early innovations, such as the switch A vertical hole, about 10 cm in diameter, from fired clay pipe walls to thin, corrugated polyethylene. Although there can be de- is dug vertically into the soil. After sign questions around issues such as the ideal pipe size, the best installation depth, waiting a day for the water level to proper installation technique, drain spacing, and maintenance, very good design stabilize, the distance from the ground guidelines do exist, and these can provide excellent results when coupled with local surface to the standing water surface in practical expertise and quality-control measures. the hole is measured. That is the depth from the soil surface to the water table. The primary challenge today is one of disposal—where to put the drainage water Saturated soil extends some distance once it leaves the pipes. The drainage water is typically saline and can also contain above the water table (insignificant on toxic microelements such as selenium. Increasingly, especially because of environ- sand; 30 cm or more on clays) because mental concerns, modernization emphasizes source control in irrigation projects to of capillary action between the water reduce the drainage water volumes. Source control is typically either by (i) reducing and soil matrix. canal seepage, or (ii) improving on-farm irrigation efficiencies. WHAT BENEFITS CAN THIS INNOVATION BRING? Fields with high water tables may not be cultivable except for rice crops. Many crops can still be grown even with a moderately high water table (less than a meter from the ground surface) but yields are typically reduced—owing to poor salinity removal and changes in the water table elevation every time the soil is irrigated. Such a sudden rise in the water table will reduce aeration and TILE DRAINAGE | 259 kill crop roots. Properly designed and installed tile drainage systems remove excess water, which lowers the water table and allows leaching of accumulated salt. In humid areas, where there is often very little irrigation, tile drainage (combined with surface drainage) can eliminate wet spots in a field after it rains. This not only increases crop yields, but also allows tractors to work in the field. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? As a well-established technology, tile drainage can be used virtually anywhere in the world. Nonetheless, success requires n Good design; n The right installation equipment; n Proper maintenance equipment; and n A destination for the drained water. Usually, tile systems have a sump (an enclosed pit) at the downhill corner of the field, and an electric pump lifts the sump water into an open drain or ditch. Typically, the pump turns on or off automatically as the sump fills or empties. DESCRIPTION OF THE INNOVATION Tile drainage is depicted simplistically in the figure on the right. Normally, the perforated tile pipes (called tile lines) should be installed as deep as possible—usually limited by the available equipment—preferably to approximately 2–3 meters. The hori- zontal spacing between tile lines can vary from about 10 meters Drainage pipes or “tile” (clay soil with a high flow rate/hectare to discharge) to 200 Water table meters (sandy soil with a low flow rate/ hectare to discharge). For any given soil and flow rate, the closer the tile line spacing, the less the water table between the tile lines will rise. Saturated soil Flow to main or ditch Tile drainage system (Source: University of Minnesota). 260 | TILE DRAINAGE The tile lines are typically surrounded by a small, dedicated gravel en- velope and/or a fabric filter. These filters or envelopes reduce the inlet velocity of the water coming into the perforations within the pipe. This minimizes the amount of silt that enters the drains. Tile lines are sometimes installed by first digging a trench, then placing the pipe in the trench, followed by backfilling. But most modern installations are “trenchless.” A special plow is used to insert the pipe in the ground at the 1 proper depth. There are a wide variety of plows. Some can automatically install gravel envelopes around the tubing. The pictures below show plows that do not inject gravel around the tubing. 1: Corrugated tile tubing and piles of gravel envelope material prior to installation. 2: Drain plow with drain tubing enclosed in a fabric envelope. 3: Drain plow with no fabric or gravel envelope around the pipe. The pipe is laid on the ground and automatically feeds into the plow. 4: Drain plow from the back. The pipe is inserted through the back tube. 5: Drain pipe being plowed in, showing laterals and collector line. 2 3 4 5 TILE DRAINAGE | 261 1 Surface Locked cover grade Flap gate High water level Minimum & Power cable maximum lift Drain Open ditch tile main outlet Start level Submersible pump Footing Stop level Sediment storage 2 3 The life of tile drainage systems largely depends on the care taken during installation, whether an envelope surrounds the tile pipe, the water chem- istry, and whether there is root intrusion from trees. Two pieces of hardware should be included in any new installation: n Air vents installed on the upslope ends of the pipes to prevent a vacuum from forming. n A specially designed hose to shoot high- pressure jets of water into the tile lines to clean them out should they ever become plugged with deposits of silt or ochre (a mix of clay and sand). Some farmers prefer to inject the water at the uphill end of laterals, others prefer the discharge end. 1: Tile drainage sump pump—a small vertical turbine pump. 2: Conceptual drawing of sump pump to remove tile water (Source: University of Minnesota). 3: Tile drain cleaner that enters from the discharge end of a tile line. 262 | TILE DRAINAGE TYPICAL COST OF INVESTMENT AND MOM REQUIREMENTS OF THE INNOVATION Approximate field costs for tile systems (excluding pumps, collector lines, and disposal off-field) are US$53,000/ha for one meter spacing between the drain pipes. The cost is proportional to the spacing; a common 100-meter spacing between pipes would, for example, cost US$530 per hectare. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS A list of standards can be obtained at: https://www.adspipe.com/resources/documents/5A84A673-737F-4A70-8994317F12F3CDCB SOCIAL, ECONOMIC, AND ENVIRONMENTAL CONSIDERATIONS The primary concern is environmental, because of the salt in the drainage water. For that reason, there should first be serious efforts to minimize the source of the subsurface water. Modernized irrigation districts with improved water delivery flexibility and improved on-farm irrigation efficiencies typically see a drop in the height of the water table. In such cases, the natural drainage capacity of the soil is often enough to remove excess water. Disposal of water tends to be relatively easy if all the following conditions exist: n The project is close to the ocean or a salt lake. n Discharge of the drainage water into the ocean or salt lake does not cause environmental damage. n The drainage water is isolated from surface drainage water and canal spills in the project, so that disposal water conveyance facilities (pipes and canals and pumps) can be relatively small. Furthermore, if the tile water is isolated, the other surface return flows can be recirculated within the project. An example of this is the Wellton-Mohawk Main Canal near Yuma, Arizona. This canal collects tile water from Arizona’s Wellton- Mohawk Irrigation District, transports the water through about 30 miles of Mexican territory parallel to the Colorado River, and discharges into the Sea of Cortez. The environmental acceptability of discharging into the Sea of Cortez is debatable. Other solutions for disposing of tile drainage water are also almost always problematic. They include: 1. Mixing tile water, field surface runoff, rainfall runoff, and canal spills in a common drainage system and discharging it into the ocean or a salt lake—which makes the good quality field runoff, rainfall runoff, and canal spills unusable. TILE DRAINAGE | 263 2. Blending the tile water with irrigation water for reuse. This works well if there is very little tile water and it is not very salty. But more typically, this practice is based on a short-sighted view that “the solution to pollution is dilution,” and this merely forces downstream irrigators—typically farmers with less economic and political power—to contend with salty irrigation water. This is the case in many projects, such as in Egypt’s delta region. 3. The tile water can be isolated from other, better-quality water and sent to a desalination plant. This has been successful in some areas but has failed in others—largely due to differences in the tile water chemical constituents. This solution is also energy-intensive and is therefore expensive, but could become a more common practice if energy costs decline in the future. Second, disposing of the brine from the desalination process remains a problem. Third, if all the fresh water is then recircu- lated within a project, downstream users (outside of the project boundaries) could face a problem with reduced flows. 4. Tile water can be isolated from other, better-quality water and then be disposed of either in an evaporation pond or on fields that have very salt-tolerant crops (such as Johnson tall wheatgrass). This is prohibited in some areas because of problems with bird poisoning. Furthermore, irrigating fields with salty water and minimal deep percolation is really just a short-term (perhaps 15-year) solution. Ultimately, the soil will become too salty to grow any crops. SPECIAL CONSIDERATIONS FOR DESIGN, PROCUREMENT, CONTRACTING AND SERVICING While the mathematics of drain spacing is well known, there are often uncertainties in drainage design regarding soil properties, the volume of water to remove, and feasible removal rates. One could examine similar soils that are under the same conditions and identify what worked best in the past. However, it may be difficult to come by that data: people seldom dig holes to evaluate the effectiveness of their water table control, so it can be hard to determine whether or not a local practice should be copied. Some contractors estimate the required pipe spac- ing and then (regrettably) start off by installing the pipes at double the spacing to save costs. Later, if problems arise, they return and install the additional tile pipes. In summary, success largely depends on the correct usage of proper equipment by experienced personnel who are not seeking to cut corners. In general, envelopes or filters of some design are highly recommended. “MATCHING” INNOVATIONS – OFTEN EMPLOYED SIMULTANEOUSLY Laser control of the slope of the injection equipment; efficient pumps; all practices that improve irrigation efficiency and reduce canal seepage. 264 | TILE DRAINAGE PRACTICAL EXAMPLES n Egypt has tile drainage on about 6 million feddan (2 million ha). n About 125,000 hectares of the Imperial Irrigation District in California, USA has tile drainage. n The Netherlands has had tile drainage systems since the 1850s. LINKS Technical documentation: ADS, Inc. 2023. Water Management Drainage Handbook. https://assets.adspipe.com/m/1219c1b77d223ed8/original/Drainage- Handbook.pdf van der Molen, W.H., J. Martínez Beltrán, and W.J. Ochs. 2007. Guidelines and Computer Programs for the Planning and Design of Land Drainage Systems. FAO Irrigation and Drainage Paper No. 62. Rome: Food and Agriculture Organization. http://www. fao.org/3/a0975e/a0975e00.htm NRCS. 2008. “Drainage of Agricultural Land.” Section 16 of Drainage Handbook. Washington, DC: Natural Resources Conservation Service of the U.S. Department of Agriculture. https://directives.nrcs.usda.gov/sites/default/ files2/1712931456/7920.pdf Tanji, K.K. and N.C. Kielen. 2002. Agricultural Drainage Water Management in Arid and Semi-Arid Areas. FAO Irrigation and Drainage Paper No.61. Rome: Food and Agriculture Organization. https://openknowledge.fao.org/server/api/core/ bitstreams/5fb994e1-ed2d-43ad-a8e7-2271ffd5f092/content Stuyt, L.C.P.M., W. Dierickx, and J. Martínez Beltrán. 2005. Materials for Subsurface Land Drainage Systems. FAO Irrigation and Drainage Paper No. 60. Rome: Food and Agriculture Organization. https://www.fao.org/4/ah861e/ah861e.pdf Drain cleaning equipment manufacturer: Homburg Holland www.homburg-holland.com TILE DRAINAGE | 265 FICHE 4.1 Controlling Upstream Canal Water Levels with Long-Crested Weirs DESCRIPTION OF THE INNOVATION 1 Long-crested weirs are the oldest “modern” structure for good upstream water level control. New long-crested weirs are commonly constructed in irrigation project modernization schemes where designers, managers, and operators want very simple and robust water level control. Long-crested weirs are not to be confused with sharp-crested rectangular weirs or broad-crested weirs—both of which are used for flow measurement rather than for water level control. A long-crested weir is a long wall over which all or most of the canal flow passes (see image on the right). It maintains a fairly con- stant upstream water level because the water depth over the wall (weir) crest is shallow—due to its long length. Because the water depth over the crest is relatively shallow, it will not change very much as the canal flow rate changes. The two bottom images show exam- ples from Vietnam. Both have flush out gates on the downstream ends, so that silt/sand can be flushed out. 1: 100-meter long-crested weir on unlined canal, pointed upstream. Boards for permanent fine-tuning are on the crest. California, USA. 2: Simple long crested weir on secondary canal. Phu Ninh, Vietnam. 3: Double long-crested weir on main canal. Vietnam. 2 3 266 | CONTROLLING UPSTREAM CANAL WATER LEVELS WITH LONG-CRESTED WEIRS Photo 1 on this page shows a common combination design that incorporates radial or sluice gates, plus long-crested weirs on the side. To be effective, the long-crested weirs must always have about 15-20 cm of water depth over them. The radial or sluice gates are then manually operated once/day or so. The operators are told to open or close them so that the upstream water depth over the long-crested weir is 15-20 cm. This combination design provides good control with a shorter long-crested weir. It is suitable for larger canals. For short canals, the fluctuations in flow rate tend to be much greater (percentagewise), so the structures are usually designed to pass all the flow over the long-crested weir. For the canal in the same photo, the contractor was late in installing the SCADA system and automation routines, so the canal (ap- proximately 100 km long) was operated manually for the first season, as described above. The operators, who were accustomed to working with radial gates that had no long-crested weirs, learned quickly and managed the canal better than previously. WHAT BENEFITS CAN THIS INNOVATION BRING? Long-crested weirs can provide extremely simple yet substantial improve- ments in water level control in canals. If they are designed and constructed properly, they can last for 100 years. HOW FEASIBLE IS THIS INNOVATION UNDER DIFFERENT CONDITIONS? Long-crested weirs are simple in concept, but there are numerous details that must be taken into consideration for good performance. Therefore, the designers must understand the details of how to determine how high and 1 long the walls should be, how to avoid uplift pressures, how to adjust the crest height if there is soil settlement or incorrect installation, how they can be mixed with other gates in parallel to reduce the required length, and so on. In some irrigation projects there is a definite dry season during which the con- struction can take place in the canal. In other projects the canals have water year-round, so the weir construction must be done on the side of the canal, with the overflow bypassing the existing check structure. 1: New check structure with automated radial gates and side long crested weirs. Government Highline Canal, Grand Junction, Colorado, USA. 2: Long-crested weir with boards supports on crest for adjustments if needed. View from upstream. Mexico. 2 CONTROLLING UPSTREAM CANAL WATER LEVELS WITH LONG-CRESTED WEIRS | 267 Even with these simple structures, operators may not understand why they are used and how they should be operated—especially if there are parallel gates. The operators need training in their proper use and purpose. Downstream farmers may incorrectly think that these structures somehow “dam up and store” water, with the result that less water flows downstream. In that case, they may destroy the structures. Some projects historically filled the canals from the downstream end, moving upstream. This can be done with long-crested weirs if there are parallel gates that can be opened when the canal is filled up. If downstream farmers suddenly see upstream farmers receiving water earlier—as opposed to previous customs, they will likely destroy the structures. In short, they are excellent hydraulic devices. But the design details must be known by engineers, and operators and farmers must be informed about their purpose and proper usage. Upstream facing long-crested weir with side flashboards. Notice the small freeboard. Modesto irrigation district, California, USA. TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS There are no typical specifications, but rather detailed design procedures. There are always standard construction details and specifications regarding concrete pouring, quality of concrete, concrete curing and reinforcing, and so on. But the hydraulic and practical design aspects for canal control are not taught in standard civil engineering or hydraulic engineering classes, so this requires special references. Design procedures are available as a “report” at www.itrc.org/reports/lcw.htm. These procedures do not include details for standard concrete forming, curing, reinforcing, etc. CANAL LINING UPSTREAM CANAL WATER LEVELS WITH LONG-CRESTED WEIRS 268 | CONTROLLING FICHE 4.2 Canal Lining BRIEF DESCRIPTION OF THE INNOVATION There are many reasons for the lining of irrigation canals: i) reduction of water lost by seepage; ii) increase of canal discharge capacity and higher velocity; iii) limitation of canal bank weed growth; iv) reduction of maintenance costs; v) reduction of damages to land adjacent to canals through soil saturation and salinization; vi) protection of canals against liquefaction during earthquakes; vii) stabilization of canals on steep terrain; and viii) preven- tion of erosion of canal banks, which causes road and bridge damage. Of the above, reduction of water losses and maintenance costs are the most frequent justification given by irrigation agencies and consulting firms . A considerable volume of water can be lost in the vast network of some irrigation canals; in other projects the loss is minimal. There is a long-standing debate, be- tween irrigation and water resources professionals, about whether canals should be lined or not, as the water lost can be captured further downstream or through groundwater pumping—un- less the seepage entered a salt sink. Canal seepage losses in one area may provide the water supply for groundwater irrigation in another area. There is no universal answer. Rather, there is a universal procedure of understanding project-level water balances. There is ample evidence of the eventual under-performance and failures of rigid concrete and brick/mortar canal lining. Hard surface linings can deteriorate within a few years, until seepage rates return to those in unlined canals. The causes of ineffective- ness of concrete canal lining over time are related to the quality of construction, the stability of the surrounding soils, regional soil subsidence due to groundwater overdraft, and the physics of seepage flow lines. For example, saturation of the soils caused by inevitable seepages through joints causes some settlement of the canal subgrade along the side slopes, resulting in a separation of the sub-base and concrete. CANAL LINING | 269 Of particular importance are canals run- ning through gypsum, karstic, and swelling clay soils, and in freezing areas. Rigid linings are badly affected in areas with swelling soils, such as in large parts of Peninsular India and in areas with the presence of gypsum such as in the Middle East region and Northern Spain. Many irrigation projects worldwide located around latitudes of about 45–55 degrees in the Northern hemisphere are affected by the effect of freezing and thawing, resulting in the dislocation of concrete Failures of canal lining in clay soils and in sandy soils in frost areas. panels and ultimately their sliding to the bottom of the canal, and in the disintegration of concrete. The effect of cold climate is further aggravated by the silty nature of the soils. The Inner Mongolia and Xinjiang Provinces in China, the central Asia countries, and the Caucasian region (for example, Armenia) have experienced serious canal lining damage related to freezing/thawing. Silty soils are sensitive to the formation of ice lenses that generate differential frost heave. Alternatives to typical concrete lining include: n Improved concrete lining with careful attention to soil preparation, concrete quality, subsoil drainage, and installation quality, n Bentonite, n Vibratory compaction of the canal bottom and sides, n Various “manufactured on-site” synthetic lining materials, n Shotcrete or gunnite, n Geomembranes: n polymeric geomembranes, n geosynthetics, n Geomembranes/geotextiles covered by concrete, gunnite, concrete slabs, rocks, etc. 270 | CANAL LINING FEASIBILITY UNDER DIFFERENT CONDITIONS Canal lining can be extremely expensive, which often makes it a poor investment choice unless it is absolutely needed. There are numerous variations to select from—it is a matter of matching the budget, quality control, climate, soil conditions, desired life, and the technology that is most appropriate to solve the problem in a specific project. If the intention is to reduce seepage, good seepage tests should be conducted to quantify the seepage rates before investing. Published tables of seepage (such as by soil type) and anecdotal reports are insufficient justification for the very large investment that canal lining requires. Poorly drained clay soils adjacent to canals may be caused by poor field irrigation, and usually canal seep- age losses in clay soil are minimal. Because most irrigation projects have inaccurate flow measurements at inlets and outlets, one should rarely estimate seepage from recorded inflow minus recorded outflows. Also, unless there are huge seepage losses, current metering to determine instantaneous losses into and out of a canal section is typically quite inaccurate. The only definitive way to quantify medium seepage losses is to conduct excellent ponding tests of canal sections (typically at least 1 km long each)—by measuring how much inflow is needed to maintain the canal water level at its design elevation (and subtracting evaporation)—preferably at the beginning, and eventually also in the middle, of the irrigation season. Canal Lining Options Options include the following: n Improved standard concrete lining. It has already been noted that concrete lining is not the best option for freezing conditions, or for specific soil types such as gypsum, karstic, and swelling soils. For other, more applicable situations, factors for success are related to the quality of concrete (and its thickness) and the preparation of the soil. Fiber-reinforced concrete is recommended. Soils should be over-excavated and then vibratory-compacted at optimum moisture as they are replaced. Equipment for vibratory compaction of earth canals. CANAL LINING | 271 The final cross section should then be neatly excavated from the over-filled, well compacted soil. In addition, special care must be taken in the execution of the joints between the different concrete panels, the longitudinal drainage system—which must be systematically gauged—and the systems to avoid ground pressures when the channel is to be emptied (pressure relief valves). In low-strength soils, rectangular sections with top tie rods should be taken into account. n Shotcrete or gunnite. This is a form of sprayed-on concrete. It is used because it is relatively inexpensive and does not require formwork. Its effective life is only about 5–10 years for good seepage reduction. The primary applications are related to limiting canal bank weed growth and stabilization of the canal banks to protect canal roads and bridges. n Bentonite. Bentonite is an expanding clay. It is often sprayed out across an empty canal cross section to reduce seepage. A better technique is to place a thin layer of bentonite under a protective soil layer. It is an inexpensive and reasonable solution in areas where there are natural local deposits of bentonite that can be dug up and transported a short distance. In addition, bentonite–cement injections can be a good solu- tion for consolidation when cavities appear between the concrete lining and the earth slope. n Vibratory compaction of the complete canal cross section. This is 1 effective for seepage reduction on soils that are neither clay nor sand but fall into some type of “loam” category. It is unsuitable for very rocky ground. It is done with locally fabricated sheepsfoot roller equipment (often scavenged from ride-on vibratory rolling sheepsfoot compactors) attached to the end of an excavator arm. The compaction is typically done within a week of emptying a canal, and will extend to a depth of at least 60 cm in the moist soil if done properly. The seepage reduction is in the 80–90% range. The primary advantage of this option is its very low cost. In California, it costs about US$7 per lineal meter (not square meter) on a canal of about 10–15 CMS capacity. 1: Spraying gunnite (shotcrete) over a membrane. 2: Application of bentonite to a canal bank. 2 272 | CANAL LINING n On-site manufactured lining with synthetic materials. This option has rarely achieved significant success. n Exposed geomembranes. The results for exposed geomembranes have ranged from excellent to horrible. The reference by Bonaiti and Fipps (2021) provides an excellent discussion and comparison. All manufacturers, of course, claim that their geomembranes are excellent and pass various quality control tests. Other than the poor quality of some materials, major problems include poor installation, animal and people damage, theft, and very importantly, the inability to remove silt without damaging the geomembranes. Because geomembranes are of high interest, a more detailed discussion of them is provided after this brief introduction. n Geomembranes covered by a thin (7–8 cm) layer of concrete. This solution can be the best in terms of longevity and life-cycle costs. It combines the best of two worlds—the mechanical protection of concrete, and the seepage reduction/elimination of the geomem- branes. There is a wide variety of options—one of the best brands uses a geomembrane with three layers, especially designed for puncture resistance and insensitivity to chemical reactions with concrete, with one layer that strongly adheres to the concrete. The reason for the slow adoption of this option is the higher initial cost. Good results require excellent geomembrane quality (which means it will not be the lowest bid), proper sealing of the joints, and proper installation especially at the tops of the canal banks. Please note that in case there is a problem in the polyethylene layer, particu- larly when there is no drainage system in place to appreciate flow increases, the consequences can be of great magnitude when the 1: Exposed geomembranes. Victoria, Australia. 2: 7 cm concrete problem is aggravated.1 over geomembrane. Mexicali, Mexico. 1 https://www.linkedin.com/posts/josem-moure_activity-7078970501510930433-TI67?utm_source=li_share&utm_content=feedcontent&utm_medium=g_mb_ web&utm_campaign=copy CANAL LINING | 273 Overview of geosynthetics/geomembranes Geosynthetics are products developed to solve civil engineering problems such as waterproofing and strengthening of soils, and to boost the confidence of dam engineers in that technology. They have also been extensively used to seal waste landfill and, in mining industries, to avoid contamination of groundwater with highly toxic fluids. The costs for irrigation canals, due to their great lengths and sizes, are much higher than for typical civil engineering projects. The geosynthetics industry has developed many geomembranes that have been used 1 for lining of irrigation canals, such as the polymeric geomembranes (PVC, polyethylene of different density, polypropylene) and other geosynthetics such as clay liners or bituminous geomembranes, and geo-composite materials consisting of an association of geomembranes and geotextiles. One of the most recent products is the geosynthetic cementitious composite mat (GCCM), a flexible concrete geosynthetic that becomes a thin, inflexible concrete layer when hydrated on-site. Each geomembrane has its own technical characteristics with specific resistance to UV, and ease of installation and welding because of dimensional variations with temperature. A gain in one quality may be countered by a loss in another. Experimental use of plastic films (generally 0.2 mm for canal lining) dates back to the 2 1960s, either with LDPE in the USSR or PVC in the USA. These films were installed either by overlapping sections or joining them with glue. Products between 0.5–2 mm were developed later by the industry. Modern equipment enables heat welding of most geomembranes. 1: Old concrete lining protected with bituminous geomembrane. Canal de Provence, France. 2: Lining with exposed bituminous geomembrane. Pench canal, Madhya Pradesh, India. 3: HDPE geomembranes protected with 200 mm thick fiber concrete. Toshka canal, Upper Egypt. 3 4 4: Geosynthetics cementitious concrete mat. 274 | CANAL LINING There are several options for the installation of geomembranes, either exposed or protected (with concrete cast-in-situ, precast panels, or any other material) against dam- age by the environment and the risk of theft and vandalism. The type of geomembrane and its thickness are two of the most important decisions at design stage. Stability along soil geosynthetics interface, risk of puncturing, stress during installation caused by high winds, and thermal expansion causing wrinkles and folds are important aspects to con- sider at design stage. Some techniques have recently been developed for installation without dewatering the canals, such as geo-mattresses and zipped geomembranes. 1 Geomembranes are often combined with geotextiles for protection of the geomem- 2 branes against puncturing or other damage during installation. Geomembranes are manufactured in a factory and transported to the project site in the form of rolls. Special care must be taken to seal the joints between the different sections of the geomembrane panels, and between the geomembranes and concrete singular works such as outlet gates and regulating gates. SOCIAL CONSIDERATIONS Seepage reduction can minimize/eliminate water logging and salinization of adjacent lands that contribute to poor crops and unhealthy conditions in villages situated near canals. This was the main justification for the program of canal lining in Fordwah-Sadiqia, in Pakistan. Canal lining of any type is subject to damage by humans and animals, but exposed geomembranes are particularly prone to damage. People may need to use canal water 3 for bathing and washing clothes, and animals may need the water for drinking or cooling. Therefore, provisions must be made to still provide for these needs or else the lining will be damaged. In general, if exposed geomembranes are used, fencing is also needed— which is expensive and very difficult to maintain properly. 1: HDPE Geomembrane protected with precast concrete panels. Vietnam. 2: Geomembranes protected with geocells filled with concrete. 3: Cattle access point. Cupatitzio, Mexico. 4: Lack of good access for livestock. 4 CANAL LINING | 275 Exposed geomembranes often provide easily-obtained, excellent roof- ing material for adjacent homes. Measures should therefore be taken to prevent theft. Lined canal sections often have steep and slippery side slopes, creating a drowning hazard as people cannot escape after entering. Typical solutions include installing floating ropes across the canal and providing stairways or ladders to climb out of the canal. Safety rope and escape ladder on a canal. TYPICAL COSTS Large variations in the cost of supply of geomembranes are expected with time, because of the variations in the costs of the poly- meric products linked to the prices of oil or rubber. Unit prices can vary substantially from country to country, depending on the source of the material—imported or not—labor cost, and imposed taxes. Quoted costs for solutions with geomembranes must be examined with caution for the following reasons: n The costs rarely include the cost of proper canal soil cleaning and preparation. n The lowest costs for geomembrane are often of the lowest quality. n The cost does not indicate how easily the geomembranes can be handled and welded in the field. n Cost estimates rarely include pressure relief valves. n There is no realistic comparison of geomembranes alone, compared to geomembrane that is covered with concrete. That is because they are quite different solutions. The concrete covering provides mechanical protection against canal cleaning, ani- mals, and people; it removes the problems of theft; and the expected life of concrete-covered geocomposite is about twice that of exposed geomembrane. Fences are needed to keep animals off exposed geomembrane; fences and gates to exclude livestock can be a significant cost and pose an extremely difficult maintenance issue. A high-quality geocomposite suitable for a concrete cover will cost about US$7/m2, excluding shipping. The cost of installation of the geocomposite alone depends upon the initial condition of the canal, the available equipment, and the skillset of the laborers. It could range from US$2/m2 to US$7/m2. Additionally, there is the cost of the concrete (7 cm thick) and its application and smoothing. 276 | CANAL LINING TYPICAL SPECIFICATIONS/STANDARDS AND MOM TECHNICAL REQUIREMENTS Most of the available specifications are related to geomembranes. An intensive program of testing geomembranes should be car- ried out at different stages: n Acceptance tests before contract signing by an independent laboratory, n Acceptance tests dispatching to the project area, n Routine tests of geomembrane rolls on arrival to the site sampling, and n Testing after unrolling seaming and associated testing. Quality tests and their frequency should be defined in the supply and installation con- Property Test Method Values tracts. The example on the right shows the specifications for a high-quality, 3-layer inert Mass per unit area ASTM D-5261 1220 g/m2 geocomposite consisting of two (top and bot- tom) 270 g/m2 polyester nonwovens, bonded Membrane thickness ASTM D-5199 0.51 mm to a 0.51 mm polyethylene geomembrane, and Grab Tensile Strength (Machine Direction) ASTM D-4632 1334 N specifically designed to adhere to a top layer of concrete. Grab Elongation (Machine Direction) ASTM D-4632 >50% Before deciding upon a specific technology, Trapezoid Tear Strength (Machine Direction) ASTM D-4533 445 N projects that have used that technology for many years should be visited. There are always Puncture Strength (5/16) ASTM D-4833 778 N critical details regarding installation and speci- fications, and key local conditions that become Permeability ASTM D-4491 Non-measurable apparent during field visits. A special consideration with impermeable membrane lining is that a high water table in the surrounding soil can lift/destroy the lining from external pressures when the canal is emptied or when the water level drops during normal operation. Special “pressure relief” or “weep” valves must be installed in the lining to allow one-directional flow into the canal. There are no good universal standards for the spacing of these valves. The 1976 USBR publication provides background information on soil preparation and options for canal lining—although it was writ- ten well before the days of geomembranes. CANAL LINING | 277 PRACTICAL EXAMPLES Examples of projects in the USA that have successfully used various technologies include: n Vibratory compaction: Central California Irrigation District, San Luis Canal Company, James Irrigation District (California) n Shotcrete/gunnite: Fresno Irrigation District (California) n Bentonite: Wind River Irrigation Project – Crowheart Division (Wyoming) n Huesker geomembrane/composite with 7.6 cm concrete cover: Columbia Irrigation District (Washington) n Numerous examples (both good and bad) are provided in publications by G. Bonaiti and G. Fipps (Texas), and by T.D. Stark and J.M. Hynes (Western USA), as detailed below. LINKS Bonaiti, G., and G. Fipps. 2021. “Evaluation of Synthetic Canal Lining Materials in South Texas Over 18 Years—Final Results and Conclusions.” Irrigation and Drainage, 71(1): 193-205. 10 August 2021. Wiley On-Line Library. https://onlinelibrary.wiley.com/doi/ abs/10.1002/ird.2639 Burt, C.M., S. Orvis, and N. Alexander. 2010. “Canal Seepage Reduction by Soil Compaction”. Journal of Irrigation and Drainage Engineering, 136(7): 479. https://ascelibrary.org/doi/abs/10.1061/(ASCE)IR.1943-4774.0000205 Ding Kunlun and Gao Zhanyi. 2020. “Development in Canal Lining Technology in China.” Irrigation and Drainage 69(1): 36–40. https://onlinelibrary.wiley.com/doi/abs/10.1002/ird.2438 Zuberi, F.A., and M.A. Bodla (eds). 1993. International Workshop on Canal Lining and Seepage. Proceedings. Lahore, Pakistan. October 1993. Wallingford: HR Wallingford. https://eprints.hrwallingford.com/329/1/Proceedings_Workshop_on_Canal_lining_ and_seepage.pdf Plusquellec, H. (In progress). Use of Geomembranes in Canal Lining. ICID. Plusquellec, H. 2019. “Overestimation of Benefits of Canal Irrigation Projects: Decline of Performance Over Time Caused by Deterioration of Concrete Canal Lining.” Irrigation and Drainage 68(1): 383-388. https://onlinelibrary.wiley.com/doi/abs/10.1002/ ird.2341 Stark, T.D., and J.M. Hynes. 2009. Geomembranes for Canal Lining. Presented at Geosynthetics 2009 in Salt Lake City, Utah. http:// tstark.net/wp-content/uploads/2012/10/CP87.pdf USBR. 1976. Linings for Irrigation Canals. www.usbr.gov/tsc/techreferences/mands/mands-pdfs/LngIrCnl.pdf 278 | CANAL LINING ATTACHMENTS ATTACHMENTS 279 ATTACHMENT 1 A Brief Historical Snapshot of Off-Farm Irrigation For millennia, farmers have innovated in irrigation. Over time, irrigation schemes have ranged from simple water harvesting to stream and river diversion developments, with often elaborate arrangements for off- and on-farm water management. Since the early Mesopotamian empires, governments have in- tervened to develop infrastructure on major watercourses. In the 19th century, innovative technology began to spread around the world. In Egypt, large barrages and canals were constructed in the Nile Delta to control the water and allow year-round irrigation. On the Indus, massive schemes were constructed that diverted water directly from the river—without storage. The second half of the 20th century saw rapid expansion of irrigat- ed area and multiple technical breakthroughs. First, irrigation was dramatically expanded through use of groundwater. Second, from the 1950s onward, hydraulic automation simplified the operation of irrigation schemes and reduced the need for manual gate adjust- ments. Third, toward the end of the century, progress made in electronics and telecommunications resulted in the automation of selective components of both on-farm and off-farm I&D schemes. With the expansion of irrigated land area came the construction of numerous dams and considerable reservoir storage capacity. Today, the process of innovation continues, with the informa- tion revolution providing evolving solutions. Meanwhile, various schools of thought on irrigation have developed that have contrib- uted to ever-more-elaborate irrigation schemes around the globe, but also to some loss of the basic impetus to innovate. 280 | A BRIEF HISTORICAL SNAPSHOT OF OFF-FARM IRRIGATION Yet within the constraints imposed on them through supply- driven schemes, farmers have reinvented, innovated, and devised a plethora of individual irrigation solutions. On many farms around the world, there have been notable advances in water application technologies that yield considerably more value from less water than was possible before. Inevitably, challenges continue to arise, and the process of I&M has strived to provide approaches and technologies to meet them. In recent years, the greatest challenges have included mounting water shortages; difficulties in managing large canal schemes with thousands of manually operated gates; emerg- ing mismatches between water service provision and farmers’ changing needs; the frequently wasteful ways in which water has been applied on farms; and groundwater overabstraction. I&M is helping farmers and scheme managers meet these challenges. However, the uptake of I&M has been far too slow, and this guide is designed to assist with the process of that uptake. Today, vast areas of irrigated land are farmed under schemes that are ill-adapted to current conditions—namely, the need for ever-higher production and productivity, farmers’ rising expectations of a decent income, the constraints and shocks of a changing climate, and the need for irrigated agriculture that helps conserve resources while protecting the environ- ment. This guide is intended to help provide a response to that context. A BRIEF HISTORICAL SNAPSHOT OF OFF-FARM IRRIGATION | 281 ATTACHMENT 2 Flexibility of Water Deliveries under Rotation, Arranged, and Demand Delivery Schedules Irrigation Water Delivery Schedule Flexibility Characteristic Rotation Arranged Demand Water can be obtained any day but must be requested in advance. Most modern projects require 12–24 hours’ advance notice as an official policy, but are often Water is available periodically, able to supply water in a quicker time such as once every two frame than that. Conversely, water may Water can be obtained at any time, without Frequency weeks. The farmer has little not be available on the day requested; any advance notice. or no choice over when it thus, users may need to wait an extra arrives. day, but this will be made explicit upon submission of their request. If a delivery is available, this will normally be at a predetermined time of day to match canal operations. The flow rate to various turnouts (delivery gates) can be different and can usually All deliveries are subject to a maximum be varied from one irrigation event to flow rate. But any rate up to that is another for a single turnout. In practice, Flow rate One flow rate available at any time, without advance most irrigators use a single flow rate at a notice. This is identical to receiving water turnout. Pressurized irrigation systems do from a faucet (tap) in a house. need different flow rates during irrigation events. Usually this is fixed. Sometimes there are rules Usually, turnouts can receive water for 12 Duration such as “a field can receive or 24 hours increments. More modernized There are no restrictions. water until it covers the whole districts allow greater flexibility. field, but without runoff”. 282 | FLEXIBILITY OF WATER DELIVERIES UNDER ROTATION, ARRANGED AND DEMAND DELIVERY SCHEDULES Irrigation Water Delivery Schedule Flexibility Characteristic Rotation Arranged Demand No human communication Excellent communication is required Little to no human communication is is required with the supply Communications between all levels (primary, secondary, required, with hardware substituted for canals. This is truly a top- and tertiary). human communication. down operation. The requested water deliveries are A demand system is completely always compared with water flow rate unworkable unless there is an extremely As the water supply flow rate availability at the source, and at the heads flexible water supply at the source that Water supply changes, the frequency of of each canal. Farmers are notified if they can be transmitted relatively quickly constraints irrigation is often changed by must wait an extra day before receiving through the system. The exception is the authorities. water. Projects with regulating reservoirs a project that diverts excess flows all and with flexible supplies can provide the time and then spills water at the much more flexibility than other projects. downstream ends of canals. For canals that cannot have any spill, there must be downstream control for the downstream portions of the canal length, Water delivery hardware Same as rotation, but the water level with a regulating reservoir at the point focuses on good water level and pressure control must extend all where the control shifts from downstream or pressure control, and the way to individual turnouts. Because control to upstream control. good flow measurement at the flow into a canal is split to many Downstream control only works on fairly the head of each hydraulic turnouts simultaneously, excellent flow Hardware flat and wide canals. If one structure fails, level. No flow measurement measurement and control is needed at Requirements everything downstream fails. Downstream is required downstream of the all individual turnouts. If a high delivery control of canals also requires automation. last level of flow bifurcation. efficiency is needed, intermediate Below that level, the flow rate temporary storage (regulation reservoirs) Closed pipelines are often used instead is the same to all turnouts is required either at turnouts or within/ of canals, but the flow into those pipelines (except for seepage losses). along the canals. must be available on demand. Pipelines and canal must both be sized based on realistic demand theory—which typically dictates larger-than-usual flow capacities. Compatibility Only suitable for surface with irrigation Any irrigation method Any irrigation method irrigation methods FLEXIBILITY OF WATER DELIVERIES UNDER ROTATION, ARRANGED AND DEMAND DELIVERY SCHEDULES | 283 ATTACHMENT 3 Improved Tillage and Furrow Formation Typical tillage operational steps are described below in chrono- logical order, starting with the first thing that needs to be done, and ending with finished furrows ready for planting. While dozens of variations1 exist, only the basics are covered below. n Deep soil ripping, done with a chisel plow or a deep ripper, breaks up consolidated or packed horizontal soil layers that will restrict downward root or water movement. n Shallow tillage incorporates the stubble from the previous crop and loosens or breaks up the soil. Depending on the soil and crop stubble, this may be done by plows, disc harrows, or simple cultivators. The equipment is configured differently de- pending on the selected depth. Examples include moldboard plows to lift and turn over the soil, sometimes shattering it. n Forming furrows from a flat field surface can be done in n In harrowing, soil clods are broken up and the top 10–15 cm several ways. The implements are often referred to as of soil are given the correct structure to accept transplants or “listers.” The two most common variations use either disc seeds. A variety of tillage implements are used to accomplish blades or shovels to form the furrows. this, often with several implements installed on the tractor’s n Final furrow or bed shaping may be required for vegeta- toolbars for a single pass. Examples include a tooth harrow bles or other produce crops. This action produces a furrow followed by a pulverizing roller to further break up clods or a or bed with a uniform height, width, and surface condition. cultipacker that can be placed on a toolbar behind a cultiva- Equipment may be a shape roller which rolls over the tops tor or harrow to crush dirt clods and form a smooth surface. of the furrow beds to compact the sides and top. Harrowing also traps moisture in the subsoil by reducing the topsoil’s moisture conductivity. This is why harrowing is often done between the first irrigation application (or rain) and the 1 When it comes to the configuration of tillage equipment, implements are planting/seeding period. often combined on one tractor to perform multiple operations in a single pass. SELECTIONTILLAGE 284 | IMPROVED CRITERIA AND FOR FURROW FORMATION ON-FARM TECHNOLOGIES—A QUESTIONNAIRE ATTACHMENT 4 Selection Criteria for On-Farm Technologies—A Questionnaire Each on-farm irrigation technology (modernized surface, sprinkler, micro) requires vet- ting against numerous criteria. For example: Does the system meet the farmer’s objective: n To grow a more profitable crop? n To improve crop yields or quality? n To extend the cropping season or to produce off-season crops? n To reduce production costs? n To increase the irrigated area or cropping intensity? Is the system suitable for the intended cropping pattern? Factors to consider include height of crops (for example tall ones, such as sugar cane or corn); pasture, alfalfa; vegetable and produce crops; grains, cotton; sugar beet; vines such as berries or grapes; trees. Is the system applicable to the conditions encountered in the field and with the irrigation service? Topographic and soil conditions: These include variability in soils within a field; uneven ground slope; hills; sandy soils; clay soils; small field sizes (for example, smaller than 20 hectares); and field shapes (regular or odd shaped). Irrigation service regime: n Does the water arrive at the field on an arranged basis with flexibility and reliability? n Is the water quality adequate (for example, very salty water, very dirty water)? n Is the mineral content of the water suitable (for example, high iron or manganese)? SELECTION CRITERIA FOR ON-FARM TECHNOLOGIES—A QUESTIONNAIRE | 285 Does the system demand high levels of design, good conditions, and excel- lent management? n Does the system only work with excellent design, suitable conditions and excel- lent management? n …or can it work well enough with average design and management and simple conditions? Are the system’s features and risk profile suitable to the farming enterprise? n How reliable is the system? Is it likely to suffer catastrophic failure—and what would be the consequences? n What are the energy requirements? What is the sensitivity to variable voltage or to outages? n What are the filtration requirements? n What are the costs per hectare? Are they lower per hectare for a larger field size? n Is the innovation labor-intensive? Does it require difficult physical labor? Or work at night? What are the unskilled labor requirements for daily operation? What level of skill is required for daily supervision? n What is the system pressure requirement? n Are spare parts, maintenance, and servicing available locally and affordably? n How great is the system’s flexibility (for example, is the manager able to control the irrigation depth infiltrated per irrigation event?) n Is periodic leaching required (periodic reclamation salt leaching required by sprinklers or flood)? How sensitive is the system to animal and insect damage? INNOVATION 286 | SELECTION CRITERIA IN CLIENT FOR COMMUNICATION AND ENGAGEMENT ON-FARM TECHNOLOGIES—A QUESTIONNAIRE ATTACHMENT 5 Innovation in Client Communication and Engagement Modern service providers have integrated management systems (IMS) that serve not only as decision support systems for the op- erator, but also for client engagement. These have been developed since the early 1990s by FAO and others in multiple countries and are increasingly accessible through mobile devices. Important fea- tures of IMS systems of relevance for “client engagement”—that is, the flow of knowledge and information between the service provider and the farmer—include: n Integration with hardware and SCADA with visualization of system inventory and decision support system (DSS); n Combination of planning and operation (scheduling, distribu- tion, monitoring); Specific innovations may be introduced to expand acces- n DSS tailormade for decision needs and information base; sibility to wider segments of the population, for example in the interests of gender access and social inclusion. n Modules for accounting/financing system; In some cases, innovations in a medium may enhance n Dialogue on and access to the Annual Management Plan; and access: for example, online portals, bank teller payment n A water distribution model and planning tool, which can include modalities, or dial-in numbers which increase access to a request module. canal operators. In other cases, technology may strengthen inclusiveness: for example, pressurized irrigation is typically, Ideally there are hard and soft components, with training and specific but not always, more accessible to female farmers due to modules focused on remote problem solving, voting, and crowd- reduced physical effort. sourcing issues. There may be flood or environmental monitoring or Service providers may also provide actual guidance to landscape design platforms for ideation. Crowdsourcing suggestions farmers about on-farm I&M and facilitate self-learning. can be translated to the irrigation management systems in future. They may, for example, provide an integrated farmer advi- There is also a long tradition of “serious games”, physical scheme sory system, with good global examples and open software models and hydraulic demonstration setups to illustrate design available. General publicity and awareness can also be choices and tradeoffs with farmers. valuable. INNOVATION IN CLIENT COMMUNICATION AND ENGAGEMENT | 287 ATTACHMENT 6 Factoring Modernization into Investment Projects Modernization has become an increasingly explicit ele- Given the step change taking ment of World Bank-financed irrigation projects. Since its place in irrigation and its future establishment in 1944, the World Bank has provided more trajectory, there is an acute than US$38 billion in financing for irrigation. In recent years, need to develop knowledge and much of this support has been for I&M, both on-farm and deepen analytical activities. This off-farm, accompanied by support for management systems, will provide guidance to national upgrading of agency staff, and improving the knowledge governments and development and skills of farmers. partners on the future direc- tion for irrigation investments, longer-term planning, and relevant The main constraints on making I&M work are weak staff investments. capacity, a lack of incentives for innovation, insufficient initial capital financing, and inadequate recurrent bud- Knowledge partnerships are a vital resource for pooling together gets to operate and adequately maintain these systems. the latest knowledge, research outputs, and empirical experiences Meanwhile, because projects combine capital finance with to deliver on I&M. Knowledge partners could include specialist institutional development and capacity building, they are agencies such as the International Commission on Irrigation and an ideal medium for introducing I&M. Hence, the ideal way Drainage (ICID), the International Water Management Institute (IWMI) to introduce these systems is as a part of a modernization and the International Food Policy Research Institute (IFPRI).1 Offering investment program in which capital funding and technical World Bank clients the opportunity to engage with relevant networks assistance are already available. is an essential element of capacity building, knowledge sharing, and financing opportunities—particularly with regard to engaging The primary factors that will shape irrigation investment the private sector. Institutional subsector strengthening can also be in the future are water scarcity and the level of economic achieved through partnerships. Lastly, a knowledge partnership may development, together with the degree of sophistication of build in secondment of their specialist staff to provide such support the irrigation economy. The likely application of the range on a cost-sharing basis. of I&M technologies depends on two main factors: (i) the degree of water scarcity—and thus the need to optimize the 1 They could also include knowledge hubs on priority topics—such as the work of value of water per drop in irrigated agriculture; and (ii) the IHE Delft in pioneering remote sensing and water productivity measurements, or sophistication of the irrigation economy and irrigation prac- research at the Massachusetts Institute of Technology (MIT) supporting energy use tice, along with the overall economic status of the country. in irrigation. EMBRACING MODERNIZATION 288 | FACTORING INTO INVESTMENT IRRIGATION INNOVATION PROJECTS AS A FUZZY-LOGIC PROCESS ATTACHMENT 7 Embracing Irrigation Innovation as a Fuzzy-Logic Process As the World Bank 2020 Governance in Irrigation and Drainage: Concepts, Cases, and Action-Oriented Approaches—A Practitioner’s Resource notes: Meaningful outcomes can be achieved, but they result from evolutionary and iterative processes that take time. They unfold in iterations of learning, requiring shifts in attitude from farmers to policy makers, changes to rigid organizational norms and sometimes need legislative reform. While this speaks of irrigation service delivery generally, it is evident that because of the intertwined nature of the social and technical domains, the path to technological change inevitably passes through cognitive and cultural territory. Over time, the pressures on irrigation continuously change, as do the goals of modernization and the motives of stakeholders The governance in irrigation and drainage resource book engaged in the process. Future options typically depend on what proposes the introduction of an Action-Learning Cycle in came before and are thus largely already implicit in current infra- innovation operations, inspired by problem-driven, iterative structure, practices, and even in the framing of the problem itself. adaptation (PDIA) approaches (the PDIA framework was devel- oped by the Harvard Institute for International Development This is true of many endeavors, but it is acutely relevant to [HIID]). irrigated agriculture, which sits at the crossroads of many devel- opment challenges. Consequently, seemingly simple technical In an inclusive participatory process, assumptions and experi- decisions—either good or bad, ranging from genuinely innovative ences are openly and routinely challenged and lead to the to tragically short-sighted—can set in motion a domino effect of incremental revision of actions and pathways. In each iteration, chain reactions that can reverberate into cropping outcomes, outcomes are further defined, uncertainty gradually decreases, environmental damage, chronic or else diminishing social ineq- and in the process key implementing agencies gain the abil- uity, vigorous growth, aborted development, or political upheaval ity to respond more reflexively and productively to changing for years to come. conditions. In other words, not only are the technical outputs in EMBRACING IRRIGATION INNOVATION AS A FUZZY-LOGIC PROCESS | 289 this process kept flexible and open to reevaluation and improvement, but also, and probably more importantly, this approach expands the “change-space” or the room for maneuver. For I&M, principled pragmatism provides a useful alternative to the more familiar, more traditional, linear, evidence-based planning and decision-making pro- cess. Rather than advocating a wholesale, just-do-it approach, several World Bank operations—in essence following the rubric of principled pragmatism—have started off with the limited, provisional piloting of this or some other novel irrigation technology. This was fol- lowed by an incremental approach to the introduction of the technology to stakeholders at the farm, system, and national policy levels to achieve the critical cata- lytic element of buy-in and ownership. The implication for project design is not to do away with systematic, cen- trally driven planning processes, but instead first to leverage the power Through tactical placement of such pilots in areas of iterative adaptation, and second, to employ limited innovation pilots where the impact will be directly felt, mindsets are to build the cognitive, attitudinal, and political space for the enablers of ultimately changed through experiential learning and change to take hold and do their work. This can be accompanied by a dialogue. In more than one case, such pilots have then willingness to experiment, depart from precedent, bravely move forward, led to broad acceptance and rapid scaling. This applies and take calculated risks, knowing that failure offers data that can be just to off-farm as well as on-farm applications. It is also im- as useful as success. portant to note that, typically, the implementing agency also uses the pilot to learn, refine, and set new goals. Nevertheless, most modernization processes span several phases and contracts, and learning can be synchronized with the contracting phases Such pilots need to be carefully designed to be em- and future asset replacement. If necessary, as well, adjustments can bedded within the currently existing—as well as the always be made with variation orders in ongoing contracts. anticipated—irrigation regime. In a more comprehen- sive system overhaul, however, there does need to be The recommendation of this Guide is to incorporate learning, piloting, a certain amount of inflexibility in terms of hydraulic iteration, experimentation, and adaptation explicitly and intentionally from infrastructure limitations, bidding specifications, con- the outset, to create a process that is more “self-aware,” more deliberate, tractual requirements, and so on. and more proactive—ultimately with fewer disruptions. EMBRACING IRRIGATION 290 | PROCUREMENT STRATEGYINNOVATION FOR CONSULTING AS A FUZZY-LOGIC PROCESS SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS ATTACHMENT 8 Procurement Strategy for Consulting Services for Irrigation and Drainage Projects This attachment has been jointly prepared by the staff from the Water Global Practice and the Operations Policy and Country Services (OPCS) Procurement team (OPSPR) of the World Bank. It examines the procurement op- tions of consulting services under large dam, water resources, and irrigation and drainage projects. The objective of the attachment is to provide Bank and Borrowers’ technical and procure- ment staff with guidance on how to strategize and plan the procurement activities, especially at the early stage of a project to meet the I. Overall Process needs of a typical Bank Investment Project Financing (IPF) project reviewing process, There are a series of consulting services engaged for producing technical studies including meeting the readiness criteria for procured for a project. Such studies normally include: (i) Pre-Feasibility Studies Negotiations and Board presentation. It reflects (Pre-FS) / analysis of alternatives, which are essential to conduct the preparation both the latest provisions introduced in Bank phase; (ii) Feasibility Studies (FS) in line with the pre-FS; (iii) Detailed Design (DD); Procurement Regulations and the sectoral (iv) Environmental and Social Impact Assessment and Management Plans (ESIA/ considerations and practices. This attachment ESMP); (v) Bidding Documents (BD)/Requests for Proposals (RFP); (vi) Procurement applies to a Design-Bidding-Build arrangement, Process Support (PS); and (vii) Construction Supervision (CS). Task teams typically which is currently commonly used in irrigation confront the challenge of appropriate packaging or grouping these studies into and drainage sector projects, although there contracts. They also run into questions of how to plan the procurement of such are other possible models to consider, such contracts in a way that meets the operational needs during the various phases of as EPC, Design-Build, Design Build Operate a project’s processes, namely: preparation, appraisal, negotiations, Board presen- (DBO), private public partnerships (PPP), etc. tation, and implementation. PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS | 291 With the completion of Pre-FS and the Bank’s project concept note (PCN) n The PP is reviewed and cleared without suf- review, Borrowers may begin preparing the Project Procurement Strategy ficient inputs from the technical team. for Development (PPSD). Once completed, the PPSD determines the The above issues are commonly addressed through fit-for-purpose procurement approach and risk management to support enhanced collaboration between the technical and the development objectives of the project and deliver the ‘best value for procurement staff as described below. money’. The PPSD provides the basis for preparing the Procurement Plan (PP), which may be finalized with the completion of a Feasibility Study (FS). Sectoral considerations In processing a typical irrigation and drainage project, various activities It is important to keep in mind that irrigation and drain- are correlated with each other according to the project timeline, as de- age projects in Bank operations have some unique scribed in the figure below. features. For example, most of them (about 80-90%) focus on rehabilitation of schemes (in- stead of new construction) and the scope Project Concept Board Note Appraisal Presentation Implementation of the civil works can only be loosely defined upfront before the feasibility study  Analysis of alternatives  Feasibility Studies (FS)  Detailed Design (DD)  Bidding documents / is completed. ideally ready Requests for Proposals  Pre-Feasibility Studies  Environmental and (RFP) The costs for use of various consulting (Pre-FS) Social Impact Assessment  Detailed costing services in an irrigation and drainage proj- and Management Plans  Procurement and  Project Procurement (ESIA/ESMP) contract award of works ect would account for about 10% of the Strategy for Development project cost. For example, in a project es- (PPSD) started  PPSD and  Supervision Procurement Plan (PP) consultancy service to be timated to cost US$100 million, the costs completed signed before works for necessary studies and designs roughly contract is signed fall under the following percentages: n Feasibility – 1% However, variations to the above flow process are often found, mainly n Detailed design + bidding documents – 2% consisting of the following challenges: n Procurement support – 1% n The Pre-FS has not been carried out, or was only briefly done by n Construction supervision – ≈5-6% experts without sufficient experience. While the main cost of a project is for the construction n The PPSD is reviewed and agreed upon without close collaboration of civil works, great potential ‘value for money’ may between Bank’s technical and procurement staff, or without explor- be achieved by commissioning high quality feasibil- ing various procurement options. ity studies through a flexible contract arrangement, 292 | PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS which allows for different technical approaches to be adequately analyzed. into procurement contracts using available funds Additionally, during the construction stage, the construction supervision (to finance these contracts) before the project is consultants may be asked, from time to time, to provide detailed designs for approved by the Bank. altered or new structures. The PPSD should also discuss the pros and cons Collaboration in producing the PPSD and Procurement Plan in selecting the appropriate contract types, such as lump-sum or time-based, or their combina- When advising Borrowers to prepare the PPSD and PP, Bank technical and tion. The Procurement Plan based on the agreed procurement staff must collaborate in addressing, among other things, the PPSD includes a list of contracts, their respective market situation, the operational context, previous experiences, and the cost estimates, selection method, Bank review, existing risks. Based on such considerations the fit-for-purpose procurement estimated times for the procurement phase, and approach and risk management can be determined to support the develop- execution ment objectives of the project. The PPSD must also outline the main issues and risks to be addressed as well as the rated criteria that are to be applied to the project. The diagram on the II. Choosing a Contract Type right summarizes key stages of The choice of contract type—lump-sum (LS) or procurement in a project 6 1 time-based (TB)—may directly affect the quality of lifecycle. CHECK IDENTIFICATION deliverables of the consulting services procured. Post implementation review. Identify development need/s, This section discusses how to choose the contract It is recommended Has the project delivered VfM? outcome/s to be achieved, What are the lessons learned? and initial time and cost type during the procurement of consulting ser- that the PPSD also constraints. address questions 2 vices in Irrigation and drainage sector projects. related to the 5 Research ANALYSIS 1. Lump-sum contract level of quality and IMPLEMENT and analyze the supply detail provided in Proactively KEY STAGES IN market. Choose a) General considerations: A lump-sum contract previous studies, manage contract implementation. PROCUREMENT appropriate selection method and approach is to be used when the scope of services and to market options. whether the analy- Prepare PPSD and deliverables can be clearly and accurately Procurement specified, and payments to be made can sis of alternatives needs to be carried 4 3 Plan. be linked to deliverables or completion of SOURCE REQUIREMENTS activities or milestones. Its most recognized out, the level of im- Approach the market. Specify the requirements provements expected, Select most advantageous and develop evaluation advantage is the easy contract management, bid/proposal. and how the required Award contract. methodology. Prepare since payments are made against deliverables to go to market. consulting services are to or completion of activities. However, there be grouped and packaged are also challenges with this contract type. PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS | 293 For example, offers are typically based on the quality of workplan and monitor their performance and inputs. On the the knowledge of staff proposed, while there is no way to other hand, this approach allows the Client to have some ensure that such qualified staff will actually work on the flexibility in managing the consultant’s inputs and contract deliverables contracted. amendments, as well as a higher degree of control of the overall quality of the deliverables produced by the consultant. b) Sectoral considerations: A lump-sum contract type may be used when technical parameters do not vary much—such b) Sectoral considerations: Irrigation feasibility studies are as, for example, those used to design a building, whose complex. They entail alternative routes to be explored, as location is fixed (and not subject to alteration) and where a spread over hundreds of square kilometers, accompanied by site investigation is available or can be done quickly during environmental and social studies and assessments . Often, or after the bidding process. Payments for such design design parameters cannot be fixed and are to be fixed during services can be based on deliverables. Lump-sum con- the feasibility study and the detailed design. These studies tracts for assignments pertaining to irrigation rehabilitation, are often not a ‘canned design’ like that of a building, but vary if including a selection of design alternatives, might also according to topography and geotechnical issues. Moreover, create a wrong incentive, as the consultant could choose various options need to be assessed, costed, and properly to focus on works that are very simple and cheap to design analyzed. During the design phase, additional social and (e.g., earthworks only, without structures). The Client would environmental demands can be made by the community in the thus receive a poor report that would fail to identify the project area that require the design to be adjusted. In addition, priority needs of a solid rehabilitation program, focusing the Independent Panel of Experts (IPOE) necessary for dams instead on simple interventions, such as embankments may often review such design and propose changes to be to be rehabilitated. As a result, the whole rehabilitation made. For example, in Pakistan, Tarbela powerhouse intake program would be flawed and fail to solve the issues faced was designed and then changed following advice by an IPOE; by the Client. consequently, its location was changed and re-designed. Such 2. Time-based contract is the nature of water works design that changes during the design process for many reasons. Many projects lack good a) General considerations: A time-based contract type quality of irrigation feasibility and designs, leading to long should be used when it is difficult to define or fix the scope periods spent on execution (original studies of 12 months may and duration of the necessary consulting services. Under end up taking 18-24 months or even longer during the process this type of contract, the payments are made based on of review and approval). This is why a time-based contract is agreed upon rates and time spent, along with reasonable suitable for irrigation feasibility studies in many cases. levels of reimbursable expenses incurred. On one hand, a time-based contract requires the Client to have adequate The following tables summarize the characteristics of lump-sum internal contract management to direct the consultant’s and time-based contracts 294 | PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS For Pre-Feasibility and/or Feasibility Studies Additional note on Pre-Feasibility Studies Lump-Sum Time-Based A Pre-FS involves the analysis of alternatives. At Appropriate if the nature of water works this stage, it is fundamental to have a sense of the Appropriate for assignments that are clearly defined and design is not clearly defined. It is easier for direction in which a project should go. Experience consulting firms to present proposals and shows that these types of Pre-FS studies need where parameters do not variations. For example, with different heights change (e.g., design of a of a dam, it is not easy to quantify the inputs, highly experienced personnel/consultants (>30 treatment plant of Xm3/day in years of experience) who can provide the nec- but it is easy to define the cost of the expert place Y). per day worked. essary guidance withing a minimum number of Pros: Easier contract Pros: Easy to adjust to site, social, and workdays (often less than one month). There are management. environmental constraints. strategic decisions to be made for the project, Cons: Difficult for Client to Cons: Requires more effort in contract such as on the possibility to introduce pressurized supervise since consulting firms management (to monitor the choice of irrigation systems (pipes), or whether it is better are paid against deliverables. alternatives and time spent). to rehabilitate or to introduce modernizations/ innovations. This is the first stage where experi- For Detailed Design ence provides a critical benefit. Additionally, it is fundamental to address questions relating to Lump-Sum Time-Based the level of previous studies, which analysis of Appropriate if irrigation feasibility studies are alternatives can be considered, and the level of Appropriate for designs complex (e.g., spread over km2, geotechnical, improvement needed (e.g., whether it is better without many variations. environmental and social issues, design issues significantly varying from FS to DD). to focus on a piped irrigation system or an open canal). Task teams are encouraged to seek support Pros: Easy to adjust to site and social and environmental constraints. It is easier for the Client and funding—such as government funding, ongoing Pros: Easier contract to ask consulting firms to prepare proposals and Bank-financed projects, and Trust Funds—for this management. variations. For example, with different heights of a type of short assignment. Quality-based Selection dam, it is not easy to quantify the inputs but is easy (QBS), Consultant Qualification (CQS), or even to define the cost of the expert per day worked. direct contracting, as appropriate, can be the selec- Cons: Difficult for Client tion method to be used. At this stage of preliminary to supervise since Cons: Payments are made on the amount of time project preparation, it is typically appropriate to payments are made upon spent by the consultants, thereby creating the need deliverables. Task team for a strong contract management protocol for engage a highly qualified and experienced consul- support needed for interim monitoring purposes. More efforts are required to tant with no connection to the future consultants reviews of the consultants’ monitor the choice of alternatives and of time spent. involved in the Feasibility Studies and Detailed work. Design. PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS | 295 III. Procurement Packaging and Planning This section discusses the possible options to group/package the consulting services into contracts, and how to plan the procurement process of these contracts to addresses the constraints in funding and meeting the needs of Bank project reviewing process, including project readiness criteria. These options do not include a Pre-Feasibility Study, which is meant to have been completed separately. Four typical options to group the services into procurement contracts are examined and explained in detail below. Option A Board This option adopts a first contract including FS, Lump Sum Time-Based DD, BD and Procurement Support (PS) under a OPTION A lump-sum contract, and a second contract for Detailed Bidding Construction (2 contracts) Feasibility Procurement Design Document Supervision construction supervision under a time-based Study (FS) Support (PS) (DD) (BD) (CS) contract. PS can be included either in the first or second contract. This option is particularly Estimated 6 12 3 3 appropriate for simple projects where the main time in months 24 months 12-36 months characteristics have been identified at the time of the Pre-FS, the scope is clearly defined, and variations expected due to topography/geotechnical and other consulting firms often do not apply through associated expres- issues are minimal. sions of interest, being aware of the challenges ahead and difficulties in undertaking the assignment. This is only appli- The advantage of Option A is the simplification of the procure- cable when technical options are defined or are easy to define ment process and contract management before the selection of without many variations expected due to challenges with the consultant for Construction Supervision (CS). It also permits topography/geotechnical and other issues. the inclusion of a first stage, called ‘review of design’, by the consultant selected for CS. However, this may become a dis- Notes: Time for elaborating FS and DD depends on the size of the advantage as sometimes the second consultant for CS tends scope. Yet, task teams should easily consider 6 months for FS and to disagree with the work done by the first consultant involved an additional 6 months for DD for scope of works in the order of in DD. This may lead to a long-term conflict that delays and US$50 million; and 12 months for FS and an additional 12 months for hinders project implementation. It may not be a ‘fit-for-purpose’ DD for scope of works of US$100 million. Spending about 15 months approach in large irrigation and dam projects, particularly as it is before Board presentation is reasonable. The second procurement very difficult for consulting companies to present a proposal for processing (construction supervision) takes place after the Board detailed design without a feasibility report in place. High-quality presentation. 296 | PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS Option B This option is, however, subject to possible difficulties in contract management under lump-sum for DD and BD in The first contract implies a comprehensive FS considering techni- cases where the consultant disagrees with the conclusions of cal, economic, social, and environmental aspects. In this case, the the FS. Thus, design needs to be properly defined at the FS second contract has two parts: (i) a lump-sum part that focuses stage. directly on the DD and BD, and (ii) a time-based part for PS and CS. This option may be ‘fit for purpose’ when Board the inputs for DD are clearly defined after Time-Based Lump Sum Time-Based completing a FS and not expecting much variance at time of the DD. The option may OPTION B Detailed Bidding Construction (3 contracts) Feasibility Procurement be particularly appropriate for a project with a Design Document Supervision Study (FS) Support (PS) secondary level of complexity. (DD) (BD) (CS) The advantage of Option B lies in the simpli- Estimated 6 12 3 3 12-36 fication of the DD and BD, provided the FS is time in months 6 months 15 months 15-39 months well defined. The first (time-based) contract allows the FS to explore different alternatives and set the basis of quantity input for design. The second con- Notes: This approach includes procurement of three (3) contracts, tract allows a DD and BD with control, and the rest (PS and CS) is which might take time. In this case, once the FS is shown successful time-based. and is appraised, project approval could follow up subsequently. PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS | 297 Option C design considering technical, economic, social, and environmental aspects. The second contract under Option C (also time-based) allows a DD with varia- Similar to Option B, the first contract under Option tions and changes, also covering BD, PS, and CS. This option may represent a C (time-based) allows the FS to explore different ‘fit-for-purpose’ approach when the inputs for detailed design are not clearly alternatives and set the basis of quantity input for defined and still can accommodate variance at the time of DD. This option may Board be most appropriate for complex assignments that require highly qualified staff and signifi- Time-Based Time-Based cant scrutiny of the various solutions to be OPTION C reviewed (e.g., by a panel of experts). Detailed Bidding Construction (2 contracts) Feasibility Procurement Design Document Supervision However, the DD portion will be difficult to Study (FS) Support (PS) (DD) (BD) (CS) control by the Client, as payment is made 6 12 3 3 12-36 based on the amount of time spent and is normally, at this stage, done mainly in the con- Estimated 6 months + sultant’s headquarters. This may be mitigated time in months 3 months for by enhancing contract management by the 30-54 months procurement Client and necessary support by the Bank = 9 months task team. 298 | PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS Option D be appropriate for complex projects that are time sensitive and with a lot of uncertainty in the project scope and technical solutions to be This option includes all services for FS, DD, BD, PS, and assessed. The main challenges of this option include commitment to CS into a time-based contract. It allows exploring dif- an expensive consulting services contract upfront, a potential conflict ferent alternatives and setting the basis of quantities of of interest between FS and downstream tasks, as well as the require- inputs for design in very complex projects. Option D may ment for consultants to commit key personnel for a very long period, Board which may undermine the transparency of the procurement process. Time-Based OPTION D All these challenges should be addressed if Detailed Bidding Construction (1 contract) Feasibility Procurement this option is to be chosen. Furthermore, a Design Document Supervision Study (FS) Support (PS) clause may be added to a contract specifying (DD) (BD) (CS) that if the project does not move forward, the Estimated 6 12 3 3 12-36 rest of the contract will be cancelled. This can time in be an appropriate approach for emergency months 36-60 months projects with significant technical difficulties. PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS | 299 Collaboration between the Bank’s technical and experts. When the number of months required for each procurement specialists key expert is mentioned in the RFP, it may leave no room for the consultants to propose and to better adapt their Within a task team, procurement work relies on close col- teams. Either way, dealing with such a challenge requires laboration between the technical and procurement specialists a review from technical and procurement perspectives. throughout the entire project cycle. In particular, their support to each other is emphasized in the following stages: (v) At the technical evaluation stage, it is crucial to properly review the technical evaluation report and, for key large- (i) At the preparation of the PPSD and PP, the technical value consulting services, technical proposals should be specialists should contribute to the review of these key requested and reviewed jointly by technical and procure- documents and discuss different alternatives with the ment specialists. Proper balance of team composition, procurement specialists. key experts’ experience, and time spent in the field (ii) At the Expression of Interest (EOI) stage, it is critical represent key aspects that are often overlooked. For to be clear on the scope and main requirements of the large infrastructure projects, multiple technical disciplines consulting services and the qualification criteria by types are frequently involved (e.g., a geotechnical expert may of deliverables. For example, a feasibility study for a be key for an earth dam but not for a concrete dam), pressurized irrigation system is very different from that which may warrant proper review by multiple technical for an open canal and this type of qualification criteria specialists of the task team to help better understand should be defined upfront in the EOI what is needed and ensure that the technical proposals are responsive to the RFP. (iii) At the shortlisting stage, following the EOI, it is important to select between 5 and 8 consultants that comply with (vi) At the financial evaluation stage. the weights attributed the qualification criteria defined. The Bank’s technical to various costs as specified in the RFP must be based specialists should review and comment on the composi- on the complexity of the work and evaluation of risks. tion of the proposed shortlist. The weight for financial evaluation may vary from 10% for consulting services of complex works to 30% for those of (iv) At the Request for Proposals (RFP) stage, where the simple works. Terms of Reference are included, it is critical to be clear on what is expected from the study (deliverables), (vii) At the time of contract signature, the minutes of negotia- the necessary team of key experts, their qualification tions and final contract shall be carefully reviewed by requirements, and the global number of months for key both procurement and technical specialists. 300 | PROCUREMENT STRATEGY FOR CONSULTING SERVICES UNDER IRRIGATION AND DRAINAGE PROJECTS COUNTRY CASE STUDIES COUNTRY CASE STUDIES 301 COUNTRY CASE 1 Successful Planning and Implementation of Modernization in California, USA By Charles Burt The Henry Miller Reclamation District (HMRD) is an old California irrigation district that has been modernizing for over 20 years. Successful planning and implementation of modernization in California has proven to be a long haul. In 2004, in response to both internal pressures (caused by the need for more flexible water delivery service) and external pressures (reduced water supplies, Before the modernization initiative, the district’s policy was restrictions on drainage outflows) that would increase in the future, to provide arranged deliveries with 24-hour advance notice the manager and the board of HMRD undertook modernization from farmers with any flow rate desired (subject to a volu- efforts. metric annual limit). But the 24-hour, on-demand, advance They began by contracting with the Irrigation Training and Research notice was somewhat incompatible with the inflexible supply Center (ITRC) to develop their first Modernization Plan (completed of water to the district. The district was able to exercise the in 2005) to provide a broad strategy for modernization. The Plan flexibility to meet farmer demand only by having a large envisaged the division of the district into three general areas, each amount of spill from the downstream ends of canals. with a regulating reservoir and drainage/spill water recirculation. A long-term investment plan was undertaken. Modernization The following three long-term goals were articulated: activities included (i) the construction of two new regulat- n Simplified water delivery operation for operators and manag- ing reservoirs; (ii) installation of long-crested weirs; (iii) ers with limited water supplies programmable-logic control (PLC) of pumps and gates for drainage recirculation and reservoir inflow/outflow; (iv) PLC n Improved water service throughout the canal system for more control of key bifurcation structures that control water levels flexible and reliable water deliveries or flow rates, (v) improved automated spill structures, canals n Operation with minimal canal spills leaving the boundaries of and pumps for drainage recirculation; (vi) improved farm the service area. This would allow the district to conserve that outlet flow measurement; (vii) implementation of a complete water and either use it internally or sell it via water transfers SCADA system; and (viii) better measurement of drainage (the latter has already served to pay for some modernization). inflows to the district boundaries. 302 | SUCCESSFUL PLANNING AND IMPLEMENTATION OF MODERNIZATION IN CALIFORNIA, USA This modernization initiative has essentially changed the charac- The district is now better able to survive drought years than ter of farm irrigation in HMRD, due to the scheduling control that before. Although this district has excellent water rights, those it has brought to its farmers (over how much water they want to rights were curtailed by about 20 percent for three years receive and when). Following the modernization efforts, water between 2015 and 2020. The improved water control allowed became available on an arranged schedule—with an unlimited the district to manage such a reduction quite well—and even to range of flow rate and duration. transfer some water. Although the official policy still requires advance notice of 24 Modernization has positioned the district better to accept new hours, it is now common for HMRD farmers to request water on challenges as well. Specifically, there are new environmental 6 to 18 hours’ notice and receive water for less than 24 hours. restrictions regarding qualities of water leaving the district Additionally, the modernization has allowed the district to mark- boundaries, and on maintenance of groundwater levels. Such edly reduce wasteful tail-end canal spillage. restrictions can be adequately dealt with since the water is well controlled within the district. Farmers were able to successfully shift to new irrigation methods that required the greater flexibility that moderniza- As of 2022, most of the initial ideas had been implemented. tion provided. Between 2005 and 2016, for instance, on-farm There have been continuous improvements in procedure, irrigation methods in the district shifted from about 80 percent re-examination of objectives and specific projects, and new surface and 20 percent drip to about 45 percent surface and 55 challenges that require more future modernization efforts. Plans percent drip.1 for further investments are part of updated modernization plans that have been developed with the district, and are expected to Modernization has also reduced the scope for error and the be implemented over 15–20 years. frequency of emergencies, and has lightened the burden on op- erators, who previously worked very long hours. The improved control reduced the number of emergencies (formerly far too frequent) and greatly reduces operator action during nights and weekends. 1 The modernization happened to coincide with a large and successful shift to drip-irrigated tomatoes. Drip-irrigated tomatoes typically provide about double the yield compared to surface-irrigated tomatoes. SUCCESSFUL PLANNING AND IMPLEMENTATION OF MODERNIZATION IN CALIFORNIA, USA | 303 COUNTRY CASE 2 Adoption of Laser Land Leveling in Punjab, Pakistan By Charles Burt Laser land leveling (LLL) was initiated in the Punjab prov- ince of Pakistan in 1984 by the On-Farm Water Management (OFWM) Directorate of the provincial Agriculture Department. At a later date, OFWM directorates of all four provinces started providing subsidized rental of LLL As part of the World Bank-funded Punjab Irrigated-Agriculture services to farmers under various World Bank- and Asian Productivity Improvement Project (PIPIP), an estimated LLL of Development Bank-funded projects—in addition to various 658,800 hectares of agricultural land was carried out, which has schemes financed by provincial and district governments. resulted in a reduction of 23,264 tons of CO2 emissions annually. After some initial trial and error, techniques were improved, By 2016, private-sector services were effective enough for the gov- and by 2006 some 285,000 hectares had been improved. ernment to end public provision and to transfer its remaining units Other provinces followed suit, setting up publicly run ser- to the private sector. Today there are more than 16,000 laser land vices. In 2006, the Punjab government decide to speed up leveling units providing services to farmers across the province. The implementation by involving private-sector service provid- overwhelming success of the technology and delivery method was ers. This intervention represented a major development replicated in other provinces, and the model has spread to neighbor- in shifting delivery of LLL services from government to the ing India and Afghanistan. private sector. The lessons from this experience include the following: Matching grants of 50 percent were also made to enable n Start modest, learn from mistakes, and adopt a step-by-step the private sector to acquire the necessary equipment progressive approach. to fulfill farmers’ ever-growing requirements for cultivat- ing over 12.6 million ha of farmland in the province. As a n Smart subsidies can create a dynamic of I&M, in this case result, annual laser land leveling capacity in the province unleashing the energy of the private sector. increased from 14,000 to 300,000 hectares per year. n The lessons of success can be disseminated and trigger I&M on a broader scale (as well as in other provinces, in neighbor- ing countries, and beyond). MODERNIZATION 304 | ADOPTION WITH OF LASER LAND LITTLE LEVELING IN PUNJAB,OR INFRASTRUCTURE EQUIPMENT IN MADHYA PRADESH, INDIA PAKISTAN COUNTRY CASE 3 Modernization with Little Infrastructure or Equipment in Madhya Pradesh, India Indian large-scale gravity irrigation systems have largely been emblem- atic of an increasing discrepancy between irrigation potential created and irrigation potential successfully exploited. Despite continuous investments to improve performance by rehabilitating infrastructure, there currently exists more than 20 million hectares of unused irrigation potential. Each week there was a video conference with the Nevertheless, Madhya Pradesh state adopted a results-oriented, modern basin office chief engineers, the superintending engi- management approach under which the canal irrigated area expanded neers, and the divisional engineers. This was chaired from less than 1 million hectares in 2010 to 2.39 million hectares by 2015. by the principal secretary and engineer-in-chief to An emphasis was placed on “last-mile projects” (that is, the last mile to discuss the ongoing situation. the farmers’ fields), a performance-oriented approach, and innovative Staff were reoriented to results delivery through a technology. reward culture—with awards for best performers; Reservoir water-level gauge readings, sent daily by gatekeepers via frequent field visits by senior staff; and the empower- short message service (SMS) to the central web-based management ment brought by digital technology, which supported information systems (MIS), were converted into stored volume based communications, performance monitoring, and system on reservoir-specific depth–volume curves. Based on these readings, management. senior management set reservoir-specific irrigated crop area targets The combination of the focus on delivering results, the for the coming winter season (rabi) at the end of the monsoon season adoption of modern management methods, strategic (mid-September). planning, and strong leadership led to remarkable Prior to the rabi season, the district office staff inspected all systems and results, with only limited investment in infrastructure reported back on required repairs and their costs, to ensure the systems and equipment. functioned well. Authority was delegated to executive engineers to undertake works needed to meet performance targets. MODERNIZATION WITH LITTLE INFRASTRUCTURE OR EQUIPMENT IN MADHYA PRADESH, INDIA | 305 COUNTRY CASE 4 An Example of Learning by Doing in Morocco Morocco has been at the forefront of the modernization of irrigation in all aspects: institutions, policy, and tech- niques at off-farm and on-farm level. It has undertaken an ambitious modernization program both for larger farmers and for smallholders. It is a good example of the process approach, and of making mistakes and adjusting. It can provide many lessons to the world. n The uptake of modern on-farm technology (mainly drip irriga- More than a decade ago, Morocco embarked on a pro- tion) was a success for individual farmers with, on average, a cess of adaptation to increasingly variable and scarce doubling of on-farm water productivity. water resources. In irrigation, the process started in 2008, n The adoption of this technology was slower for small farmers with the National Program for Water Savings in Irrigation in WUAs, largely due to the heterogeneity of farmers’ interests (PNEEI—Programme National d’Economie d’Eau en and implementation delays. Irrigation). This ambitious program of I&M had two main objectives: (i) to improve water delivery service, and (ii) to n The conversion to modern on-farm irrigation equipment did not increase water productivity, with the expectation that this lead systematically to a reduction in the consumption of irriga- would “save” water. tion water at farm level. In fact, many farmers equipped with drip irrigation used more water in order to grow higher value crops, In its initial years, the program focused primarily on pres- thus contributing to further overexploitation of aquifers. surization of water delivery networks and the subsidized promotion of micro-irrigation technologies. After the The assessment concluded that a course correction was required—in program had been under implementation for twelve years particular, that in order to maintain water withdrawals at a sustainable (2008–2020), government and the World Bank carried out level, complementary water conservation policies were required a major assessment. The main findings were: in parallel to the technology upgrade. These policies provided for strengthened regulation and collective aquifer management, and for a system of annually determined transferable water quotas. 306 | AN EXAMPLE OF LEARNING BY DOING IN MOROCCO The future will tell on the robustness of the I&M process in n The I&M process is not a linear roll-out of an “ideal solution”, Morocco, but it is evident that, through years of partnership and but a trial-and-error pragmatic approach with piloting, partially learning on the mix of instruments, the acceptance of and ability failing, learning, and adjusting. to venture into new conservation policies is higher now than it n The I&M process conducted on this basis can gather was in 2008. Trust has been built, a knowledge base has been strength—in the PNEEI case, the implementing agencies established, farmers have seen the benefits of modernization, gained confidence, knowledge, and technical capacity to and there is an acceptance of the need to adjust water alloca- reformulate the program; and farmers saw the benefits, but tions to deal with future water realities. also understood the need for further changes. In 2022 the World Bank approved further support for PNEEI n Change materializes in a politically attuned process that (as part of the Resilient and Sustainable Water in Agriculture allows for piloting, learning and course-correction within the (RESWAG) project) that includes a number of pilots, policies and authorizing environment. investments designed to help advance the new thinking and ensure adaptive implementation of modernization in the coming n I&M is usually not technology alone—in the Morocco case years. There is special provision in the project for M&E and im- it proved that technology aimed primarily at water use ef- pact evaluation to strengthen the I&M feedback loop. Important ficiency will not save water unless accompanied by water lessons from PNEEI for I&M processes are as follows: conservation policies. n Objective M&E and impact evaluations are essential—they support learning and course correction. AN EXAMPLE OF LEARNING BY DOING IN MOROCCO | 307 COUNTRY CASE 5 National Water Initiative Provided a Consensual Framework for Irrigation Modernization in Australia In the 1990s, Australia was experiencing extreme water short- ages. The nation conducted an inclusive process of study and debate to arrive at consensus on a national water reform agen- da, the National Water Initiative. This comprehensive reform plan set three goals for water resources management: (i) to return all Lessons of the Australia experience include: water systems to sustainable levels of extraction; (ii) to manage n The value of broad stakeholder involvement in arriving at groundwater sustainably; and (iii) to respect needs for environ- a consensus on a difficult reform agenda mental water. n The need to set irrigation water withdrawals within an Three goals were also set to improve water allocation: (i) overall framework of water resource availability and providing secure water entitlements for irrigation; (ii) securing allocation water entitlements for the environment; and (iii) introducing water sharing plans with legal force. The provisions for demand n The need to incentivize farmers by balancing reduced wa- management introduced water pricing based on economics ter allocation and higher service charges against secure and ensured support for affected communities where irrigation water entitlements. supplies were reduced. Finally, the initiative provided for bet- ter water services, particularly in improved management and security of irrigation water supplies. IRRIGATION 308 | NATIONAL MODERNIZATION WATER IN BRAZIL A CONSENSUAL FRAMEWORK FOR IRRIGATION MODERNIZATION IN AUSTRALIA INITIATIVE PROVIDED COUNTRY CASE 6 Irrigation Modernization in Brazil by José Simas The total irrigated area in Brazil spans across approximately 8.2 mil- lion hectares and is expanding at approximately 200,000 hectares per year (as of 2019). The main crop under irrigation is sugarcane (44.55%). Private irrigation represents the majority, as compared to irrigation perimeters (areas) with collective infrastructure. The government set out three national objectives for the sector: The investment costs and electricity were not subsidized as (i) equity in distribution; (ii) improved efficiency; and (iii) environ- part of this program for irrigators in the collective irrigation mental and financial sustainability. As part of a state program, an zones of São Francisco River Valley that use large pumping extension of electrical networks in the collective irrigation zones stations. Typically, full cost recovery is practiced for both of the São Francisco River Valley was undertaken along with their agribusiness and smallholders (including on collective irriga- modernization. tion schemes). If an electricity bill is not paid, the subscriber’s supply is cut off. And in many perimeters of service delivery, The extension of access to the electricity grid included large a composite fee (binomial pricing) was imposed from the pumping stations. The associated modernization strategies gave beginning, accounting for both fixed and variable costs priority to the extension of electrical networks to enable pressurized (based on volume of water consumed) by installing meters pumping. Modernization efforts in collective irrigation perimeters and flow limiters. predominantly consisted of replacing tertiary networks of canals by pressurized pipes (with pumping stations) and reservoirs. As a result of the program, collective irrigation areas that were previously characterized low irrigation rates due to Given high electricity costs and considerable differences in en- high electricity costs (where farmers were only able to ergy cost between peak and off-peak hours, the pressurized pipe irrigate 50% of their plots) were able to switch to irrigating systems installed included the capacity to stop during peak hours during off-peak hours (with lower associated costs). Farmers without interfering with the operation of the canals. These systems were thus able to expand their irrigation to 100% of the thereby promoted irrigation during the hours of lowest energy cost. cultivated area allotted and benefit from lower off-peak electricity tariffs. IRRIGATION MODERNIZATION IN BRAZIL | 309 Overall, the program for the extension of electrical networks al- n Modernization can create the profitability that will allow for lowed for the development of irrigation at lower cost. As a result full cost recovery even from smallholders. With moderniza- of these interventions, the irrigators were also able to benefit tion comes increasing market-orientation and profitability for from lower off-peak electricity tariffs. Moreover, irrigating farm- irrigators, and this can underwrite a move toward full cost ers also gained access to advanced technology that enables recovery and “irrigation as a business”. evapotranspiration and soil moisture control with use of data n Where irrigation is treated as a business conducted in con- derived from satellite imagery. formity with clear public interest guidelines, it can expand Lessons from the Brazil experience include the following: rapidly toward its full potential. n Complementary investments, for example in the electricity grid, need to be synchronized with irrigation moderniza- tion plans—thereby expanding the range of modernization options. THE NATIONAL 310 | IRRIGATION IRRIGATION MODERNIZATION MODERNIZATION IN BRAZIL PROGRAM IN ARGENTINA COUNTRY CASE 7 The National Irrigation Modernization Program in Argentina By Luis Ruiz Casquero The National Irrigation Modernization Program comprises a flex- ible menu of innovations in pursuit of water saving and higher efficiency. Argentina’s higher-level goal of water saving was a response to increasing demand and declining water resources. Irrigation in Argentina was historically a classic top-down system poorly adapted to crop needs. Systems experienced very high water losses (averaging 70 percent). As climate change ratchets Lessons from the Argentina experience include the following: up the urgency, the national priorities are to expand irrigation n The value of clear overriding objectives—in this case to solve while saving water by reducing losses and improving efficiency. the problem of growing water scarcity while encouraging a The National Irrigation Plan aims to increase efficiency, thereby large expansion of the irrigated area. saving water and allowing a doubling of the irrigated area. A n The virtue of a flexible menu allows for trial and error and first phase of modernization offered a flexible menu of different for progressive adoption of the modernization options best innovations to suit different contexts. These options were tested suited to local conditions. and then each scheme developed a program of progressive modernization. The most frequently adopted innovations have been aimed at improving water control and reducing losses from the network. In sloping areas, pressurized networks have been built to oper- ate on demand. Some surface irrigation schemes are also being converted to more flexible irrigation on demand. For ground- water irrigation, flow meters with teletransmission of data have been introduced to monitor abstractions. THE NATIONAL IRRIGATION MODERNIZATION PROGRAM IN ARGENTINA | 311 COUNTRY CASE 8 The Public and Private Sectors Working Together in Israel By David Meerbach In Israel, water resources and water distribution were national- ized soon after independence in 1948. At the time, the emphasis was on irrigation for national food self-sufficiency, but over time the irrigated sector has moved away from collective farming for food security toward commercial farming agribusiness. Beginning in the 1980s, with rising demand for water and scant The lessons are that: water resources, the government gradually reduced subsidies (although some level of nongovernmental subsidy continued). n Even the most difficult of transitions can be turned to good The government also reduced water rations for irrigation and advantage if farmers are counted as partners and fully en- moved toward rationing by price. Piped, pressurized convey- gaged in the process; and ance to all farms nationwide was accompanied by wholesale conversion to using treated wastewater for irrigation and by n The incentives created by lower—but guaranteed—water allocations and by higher water prices can create a powerful rapid modernization of all aspects of irrigated agriculture. dynamic of I&M. Innovation has been continuous, and the public and private sec- tors have worked together, with government support to private sector research and development, including through innovation, incubator grants and facilitating investments in large storage reservoirs. This public–private cooperation has resulted in a highly efficient, export-oriented irrigation sector and in substan- tial exports of Israeli irrigation innovations. IRRIGATION 312 | THE AND PRIVATE SECTORS PUBLIC MODERNIZATION WORKING TOGETHER IN ISRAEL IN SPAIN COUNTRY CASE 9 Irrigation Modernization in Spain by Luis Ruiz Casquero In Spain, 50 percent of 3,700,000 hectares under irriga- tion schemes have been modernized from 1996 to 2017, with the objectives of (i) improving efficiency, flexibility, and reliability of service provision; (ii) enhancing the competitiveness and profitability of the agricultural sec- In addition to the actions listed above, farmers agreed to migrate to tor; and (iii) improving the environment. localized or sprinkler irrigation systems (in many cases pivots). The modernization process involved: Moreover, the cost of electricity is generally the highest cost in irrigated i. Parcel concentration; production. The sector has thus become the second largest consumer ii. Construction of regulating or buffer reservoirs (to of electricity. Irrigating communities have, therefore, organized them- absorb the gap between supply and demand); selves to buy electricity directly from the electricity market to lower their costs. In some cases, progress has been achieved by installing iii. Pumping stations associated with reservoirs (with solar panels, which, at least partially, cover the need for electricity. collective filtering stations at 1–2 mm, with frequen- cy variators in some of the pumps that pressurize a In some water user associations (WUAs), solar panels have been network of pipelines); and placed on floating structures within regulation reservoirs, thereby improving the performance of the photovoltaic panels, reducing direct iv. Substitution of tertiary canal networks (and, in evaporation, and reducing the growth of algae in the reservoirs. some cases, secondary ones) by underground pipe networks with hydrants to be provided on the plots Water savings attained as part of the modernization and innovation (shut-off valve + Y-strainer + pressure reducer valve efforts were lacking due to efficiencies gained through increased avail- + flow meter + trifunctional air valve). ability of water for irrigation and its improved application. This allowed for increased crop production and higher overall water use, thereby enhancing the kg/m3 ratio (productivity) with similar or even higher annual volumes. To reduce this rebound effect (or Jevon’s paradox), the following actions were undertaken: IRRIGATION MODERNIZATION IN SPAIN | 313 n Firstly, revision of concession rights for modernized ir- Overall achievements of the modernization efforts in Spain include: rigation systems were undertaken to maintain constant n Savings in water abstractions water consumption by crops. Additionally, a prohibition on increasing the irrigated area by using water savings n Increased guarantees for all water users, including the from modernization was instituted. Lastly, prioritiza- environment tion of modernization efforts in irrigable areas located n Adaptation to climate change in the tailwaters of the basins (lower reusable return flows) was promoted. n Increasing land, water, and labor productivity n Increasing direct and indirect employment in the rural areas n Furthermore, irrigation modernization works have been carried out in a context of updating the basin n Increasing the quality of agricultural work hydrological plans, where various water uses were n Allowing for the implementation of the volumetric fee. considered, with a priority given to ecological flows as well as in scenarios where climate change implies a distribution of the rainfall regime with a worse use for crops. DRAINAGE WATER 314 | IRRIGATION REUSE FOR IN MODERNIZATION SPAIN IRRIGATION IN EGYPT COUNTRY CASE 10 Drainage Water Reuse for Irrigation in Egypt By Atef Nassar Water deficiency in Egypt is estimated at 20 billion cubic meters in a year. Reuse of agricultural drainage water (ADW) represents an integral supplement to the freshwater supply in the country, with farmers typically using drainage water to cope with the shortage of irrigation water (by tapping into drains with pumps). water and mitigates water shortages at branch canal tail ends Despite its higher salinity levels, ADW is considered a strategic (while requiring use of smaller pumping stations). It also mini- option for coping with increasing freshwater demands in the mizes incentives for illegal use of contaminated drainage water country. The method encompasses recovering relatively good and encourages farmers to engage in water resources manage- quality water from branch drains and directly discharging it into ment. Moreover, such localized drainage reuse system can be the nearest branch canal to be reused for irrigation purposes. controlled by the irrigation district. Moreover, mixing drainage water with freshwater increases its As part of the Al Mahsama Agricultural Drainage Treatment suitability for irrigation, particularly for salt-sensitive crops. To Project (which became active in 2020), the latest technolo- that end, under optimal conditions (of good quality freshwater gies were utilized to treat agrarian drainage water to produce available for irrigation), up to 80% of available ADW can be water suitable for irrigation and land reclamation. Al Mahsama reused, thereby constituting up to 40% of the total irrigation is considered the largest plant of its kind in the world (built over demand (during main cropping seasons). 42,000 square meters) and provides the capacity to process 1 million m3/day, thereby supplying 70,000 acres in the Sinai Upstream branch drains can be used to recover relatively good Peninsula. quality ADW for reuse in irrigation, instead of withdrawing it from main drains (as part of intermediate drainage reuse). Such a method reduces the chance of unknowingly using contaminated DRAINAGE WATER REUSE FOR IRRIGATION IN EGYPT | 315 COUNTRY CASE 11 Irrigation Modernization in the Sierra Region of Peru By José Simas In Peru, both the Highland areas (known as Sierra region) and Amazon areas (known as Selva regions), although endowed with abundant water resources, use rudimentary irrigation systems. Most of Peru’s poor live in Sierra and Selva, where they rely on subsistence or small-scale farm- Moreover, water is rarely metered, and fees are mostly based on ing. In the Sierra, small-scale farms prevail and the main irrigated area rather than volumetric metering. Inadequate irrigation crops are diversified and combined also with fodder for management, together with inefficient irrigation systems, lead to livestock. pervasive irrigation practices, with farmers applying more water than crop requirements and water availability. Problems of low and un- In the Sierra and Selva, with 97 percent of Peru’s water sustainable O&M fees, deferred maintenance, and loss of irrigated availability, surface water supplies agricultural fields mainly area (e.g., due to salinization) prevail, as do institutional challenges. by gravity methods like furrows, borders, or flood irriga- tion. Less than 5 percent of irrigated land is equipped with The World Bank’s Sierra Irrigation Subsector Project has had suc- improved on-farm irrigation systems. The collective irrigation cess in promoting the dissemination of good practices for irrigation systems consist of an open canal network, generally unlined, modernization and improvement of technology used by small-scale with rudimentary water intakes and distribution systems sup- farmers within 12 water user organizations. plying small plots devoted mostly to subsistence agriculture. Lessons learned from the WB Sierra Project demonstrated that Much of the irrigation water (65%) is lost due to reliance on there is still a need for large improvements in the irrigation and inefficient off-farm irrigation canal systems. When all the water resources regulations in Peru, which led to a follow-up op- losses are considered, including the on-farm application, eration. They include highlighting the applicability of low pressure the overall efficiency of water use in irrigation systems is piping as well as the volumetric and continuous recording of flow estimated at about 35 percent. This is considered poor measurement. Piped water distribution allows for easier ways to do performance and is due mainly to leaky distribution systems water metering, which is much needed in Peru. A reliable metering and the wide use of unimproved gravity and flooding irriga- system is the first stage in implementing adequate cost recovery, tion methods with an efficiency of around 50 percent. which supports O&M. SETTING THE 316 | IRRIGATION MODERNIZATION BAR ON MODERNIZATION: IN THE SIERRA CANAL DE PROVENCE REGION OF PERU IN FRANCE COUNTRY CASE 12 Setting the Bar on Modernization: Canal de Provence in France By Henri Carron The Société du Canal de Provence et d’Aménagement de la Région Provençale (SCP) was created in 1957 to build and man- age the Canal de Provence and other works necessary for water supply in eastern and coastal Provence. It represents a semi-public entity that fulfils a public service of abstraction, conveyance, and distribution of water for all its uses. The primary use served by SCP As a result, design principles of modern irrigation systems is irrigation. Other uses include supply of drinking water, industrial were defined—along with concepts and methodologies—in uses, firefighting, etc. By way of concession, SCP builds, operates, the 1960s and 1970s, and served as a major reference for and maintains all the works of the Canal de Provence. projects focused on modernizing irrigation schemes, or in A notable figure, René Clément was significantly involved in the developing new ones, both in France and internationally. design and construction of Canal de Provence and is considered When it came to determining crop water demand (based a pioneer of modern irrigation canal design. Following the comple- on a scientific approach) and provision of related advice tion of the works, he served as the director of the company for the to farmers under the premise of ‘rational water use’, SCP next 14 years. (along with research institutes) conducted a study focused René Clément is credited with SCP’s transition to modern pres- on an evaluation of crop coefficients at different stages of surized networks from traditional irrigation (to enable provision of crop development. Crop coefficients (defined as the ratio on-demand water service). This transition was based on an under- of actual crop evapotranspiration to reference crop evapo- standing that, in the SCP’s concession perimeter, soil quality as well transpiration) were involved in estimating the actual water as the topographical features of irrigated areas were not conducive consumption of crops sufficiently supplied with irrigation. to the implementation of a system of traditional canals that operate The study contributed to the development and promotion under water scheduling. of new methods of irrigation as well as the modernization of traditional methods. Such research and consulting activities continue to accompany the necessary adaptations promoted for improving irrigation water service to farmers. SETTING THE BAR ON MODERNIZATION: CANAL DE PROVENCE IN FRANCE | 317 In 1955, René Clément devised a method for calculating flows in Water service pricing was René Clément’s third major innovation, “on-demand” pressurized irrigation systems, where the user was designed specifically for the needs of SCP since its inception. In no longer subjected to irrigation scheduling, but became free to traditional irrigation systems, the pricing of water service deliv- irrigate as per crop water requirements. Based on this method, ery was proportional to the size of a user’s field, independent he established two formulas for calculating appropriate flow of the level of use of distributed water. For SCP, the search for a rates in accordance with crop water demand. new pricing system drew on research developed by Électricité de France (EDF). It was based on theoretical principles for a The first formula was based on relatively simple statistical fair and more incentive-based solution, and thus the one most calculations to estimate the demand and is universally known consistent with the basic principles of service delivery. as Clément’s formula. It is now used by scheme designers in the calculations for new irrigation networks, and by operators in The above approach enabled differentiation as part of the tariff determining the appropriate level of water deliveries for existing structure according to various uses of water (agricultural, urban, networks. The second, more complex formula, is less known but industrial) and whether the usage is permanent or temporary. offers a tremendous potential to determine the likely evolution It also considered the nature and importance of the civil works of flow in a particular section by knowing its value at any given and services necessary for end-user satisfaction. This pricing moment, and can serve as support for water regulating devices/ structure was, therefore, based on the principle of a dual tariff, structures. Today, Clément’s formula still represents the domi- whereby a fixed premium contributes towards investments and a nant method used by SCP in the design of new networks and to variable component (based upon the subscribed flowrate) that is track the performance of networks already in service. proportional to the volume used, which covered operating costs of the network. The tariff calculation was also made based on a Dynamic regulation of canals was another major innovation es- long-term forecast that accounts for various expenditures and tablished by René Clément—applicable to canal networks built revenues. prior to the creation of SCP on the principle of upstream control regulation. The main branches of the Canal de Provence were designed based on the downstream control principle and pro- vide an advantage over upstream control by virtue of improved adaptation to fluctuations in demand (as generated by modern networks) to help reduce water losses and ensure the quality of water service to beneficiaries. This technology, designed and developed on SCP’s canals, has been exported internationally, notably on canals managed by the Haouz Regional Agricultural Development Office (ORMVA) in Morocco. ENABLING 318 | SETTING ACCESS THE BAR ON TO MODERNIZATION: FINANCE FOR IRRIGATION CANAL DE KENYA INPROVENCE IN FRANCE COUNTRY CASE 13 Enabling Access to Finance for Irrigation in Kenya In Kenya, agriculture contributes contributes 24% of GDP, employs 75% of the national labor force, and accounts for 65% of Kenya’s total exports. Agriculture is the most water-intensive sector in Kenya, accounting for nearly 60% of water withdrawals, while the country faces freshwater scarcity. Making the shift from uncertain rainfed agriculture to efficiently irrigated agriculture could trans- form agricultural water management in Kenya, through expanding To promote irrigation in Kenya, the East Africa Irrigation irrigated areas, increasing agricultural productivity and profitability, Financing Facility (established by 2030 WRG and anchored and resilience to climate change. in IFC) is working to increase access to water productive irrigation systems for smallholder farmers who are part of Meanwhile, only 3% of arable land is irrigated. Smallholder farmers structured supply chains.1 Such efforts leverage partnerships account for 75% of agricultural output, but struggle or are unable to among key stakeholders across the value chain—banks, access water-efficient technology for irrigation. Irrigation is mainly equipment providers, smallholder farmers, and off-takers— conducted by using simple surface schemes (except for the com- with cooperation agreements in place. 2030 WRG was able mercial farms). Smallholder farmers typically use rainfall and/or to develop partnerships between financial lenders, farmers, buckets. major challenges have limited smallholder farmers’ uptake off-takers and equipment suppliers to stimulate lending, help- of efficient irrigation systems due to lack of tailored financial prod- ing to test the market. ucts, limited irrigation infrastructure, limited product offerings, poor market linkages, lack of knowledge, lack of value addition skills, and weak institutional capacities. 1 Although interventions targeted at smallholders in unstructured supply chains have the largest water efficiency impact potential, accessing them requires overcoming many challenges. Financial service providers are more willing to provide consumer financing in structured supply chains— where input and output market linkages already exist—than in unstructured value chains. ENABLING ACCESS TO FINANCE FOR IRRIGATION IN KENYA | 319 The model convenes stakeholders from across the value chain to catalyze increased investment in efficient irrigation (see diagram below). With a first loss guarantee in place, the financial institution lends to the “buyer” (e.g., trader, aggregator, or exporter) to purchase irrigation technology (e.g., equipment) on behalf of the farmer(s). The provider then supplies the irrigation technology or equipment as well as technical assistance to the farmer(s). Finally, thanks to an increased yield, the buyer pays back the loan to the financial institution. Yield Increases TA Equipment + Credit Equipment TA Enhancement Supplier 1 Farmers Equipment + Financial Buyer Equipment TA Institution(s) Trader/Processor/Exporter Supplier 2 Farmers Equipment + Equipment TA TA Supplier 3 Farmers Yield Increases Product / service flows Financial flows A pilot project is working with a loan portfolio of approximately USD $1 million, servicing 500 out-growers, alongside equipment suppliers, off-takers, and two commercial banks to provide access to credit, training, and agronomic support to smallholders who require irrigation systems. The next phase of this work will select 2-3 of the business models identified during the first phase to bring them to scale by working together with farmers and linking them to financiers. 320 | ENABLING ACCESS TO FINANCE FOR IRRIGATION IN KENYA BIBLIOGRAPHY BIBLIOGRAPHY 321 ASCE. 2014. Canal Automation for Irrigation Systems. Manuals FAO. 2008. 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Practitioner-s-Resource.pdf org/10.17582/journal.sja/2022/38.4.1352.1360 324 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE PHOTOGRAPHY IMAGES 325 Cover Eddie Oosthuizen / Wikimedia 57 Ivuvisual / Wikimedia 160 (4,5,6) Charles Burt; (7) Kyle Feist; (8) Charles Burt 6 Anrita / Pixabay 58 Water Alternatives / Flickr 167 Sylvain Lanau / Water Alternatives 7 Fox Photos / FreeImages 59 Tom Fisk / Pexels 176 Myriam Saadé-Sbeih / Water Alternatives 8 Joel Dunn / Unsplash 63 IFC 179 (2) Charles Burt; (3) Mississippi State University 9 u_cq5nour74s / Pixabay 64 Jorge Sánchez Paucar / Water Alternatives Extension Service 11 Samurdhi Ranasinghe / IWMI 65 IFC 187 (1) World Bank; (2) Charles Burt 13 Mike Bing / Flickr 67 Martin Laurenceau/IRD / Water Alternatives 188, 189 (all) Charles Burt 16 European Space Agency / Wikimedia 68 Rod Waddington / Wikimedia 190 (1,2) ITRC; (3) Charles Burt 17 Süleyman Şahan / Pexels 70 Jean-Yves Jamin / Water Alternatives 191, 192, 195, 196, 197, 198, 199 (all) Charles Burt 18 Mark Stebnicki / Pexels 200, 201 Faseeh Shams / IWMI 72 François Molle / Water Alternatives 19 Pascvii / Pixabay 203 South African Tourism / Wikimedia 73 Spencer Wing / Pixabay 20 Winand Uys / Unsplash 205, 206, 207, 208, 209, 210, 214, 215, 216, 217, 218 76 PAC Program, Brazil / Water Alternatives (all) Charles Burt 21 CODEVASF / Water Alternatives 79 Max Barñers / VisualHunt 220 Hamish John Appleby / IWMI 23 Kallerna / Wikimedia 80 Jonathan Billinger / Wikimedia 221, 223, 225, 226, 228, 231, 232, 233, 234, 235, 24 Bruno/Germany / Pixabay 81 Tony Wu / Pexels 244, 245, 248, 250, 251, 252 (all) Charles Burt 25 François Molle / Water Alternatives 82 François Molle / Water Alternatives 254 (1) Google Images; (2) Charles Burt 27 ICRISAT / Flickr 83 Jonathan Denison 255, 261, 262, 266, 267, 268 (all) Charles Burt 28 NASA / Wikimedia 84 Jaime Hoogesteger / Water Alternatives 269 Judgefloro / Wikimedia 29 Frankie Lopez / Unsplash 85 Daniel Kawed / Unsplash 270, 271, 272, 273, 274, 275, 276 Charles Burt & 30 Hamish John Appleby / IWMI 86 rjcox / VisualHunt Hervé Plusquellec 31 Jean-Yves Jamin / Water Alternatives 89 csemcsem / Pixabay 279 Ramon Ramos / Pixabay 32 Neil Palmer / IWMI 90 Karen Conniff / Water Alternatives 280 Georges Perrot & Charles Chipiez / Wikimedia 34 guiandrade / FreeImages 91 abcdz2000 / FreeImages 281 Florence Low/DWR California / Water Alternatives 36 Nabil Kherbache / Water Alternatives 92 Hamish John Appleby / IWMI 284 Chris Austin / Water Alternatives 37 CODEVASF / Water Alternatives 96 John Kelley/USDA / Flickr 285 Adele Payman / Unsplash 38 Jaime Hoogesteger / Water Alternatives 99, 100, 101, 105, 106, 110, 111, 116, 117 (all) Charles 286 Thinkstock / FreeImages 40, 41, 42 François Molle / Water Alternatives Burt 287 Beth Cullen/ILRI / Water Alternatives 43 Faseeh Shams / IWMI 118 (2) Charles Burt; (3) Stuart Styles 288 Prashanth Vishwanathan / IWMI 44 Jean-Yves Jamin / Water Alternatives 119 (2) Charles Burt; (3) Glenn-Colusa Irrigation District 289 Almin Zrno / World Bank 45 Chris Austin / Water Alternatives 120 (2) ATEO Group; (3,4) Charles Burt 290 CODEVASF / Water Alternatives 46 Brad Smith / Flickr 125 (1) Stuart Styles; (2,3) Charles Burt; (4) Mark Barnett 291 Shynar Jetpissova / World Bank 47 Oleksandr Ryzhkov / Freepik 126 (1) Ram Dhan Khalsa; (2,3) Charles Burt 297 Philippe Floch / Water Alternatives 50 Colin-47 / Flickr 130 (all) Charles Burt 298 PAC Program, Brazil / Water Alternatives 51 Hamish John Appleby / IWMI 131 (1) Charles Burt; (3) Hervé Plusquellec 299 Florence Low / Water Alternatives; 53 ryochiji / VisualHunt 133, 134, 135, 137, 140, 143 (all) Charles Burt 301 Jesse Allen / NASA 54 François Molle / Water Alternatives 151 David Arrowsmith & USGS / Unsplash 321 Lien Arits / IWMI 56 Chris Austin / Water Alternatives 159 (1) Charles Burt; (2,3) Kyle Feist 325 readerwalker / VisualHunt 326 INNOVATION AND MODERNIZATION IN IRRIGATION AND DRAINAGE