Publication: Return on Investment in Green Urban Development: Amelioration of Flood Risk in the Msimbazi River Catchment, Dar Es Salaam, Tanazania

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Turpie, Jane
Kroeger, Timm
De Risi, Raffaele
de Paola, Francesco
Letley, Gwyneth
Forsythe, Katherine
Day, Liz
Rapid urbanisation is taking place at an unprecedented rate throughout the world, with the rate of growth often outpacing urban planning and the capacity of city managers. As a result, existing natural areas within cities,which provide a range of benefits to urban dwellersare becoming smaller and degraded, and problems such as flooding, air pollution and water pollution are becoming worse in many places. African cities often lackthe resources to deal with these problems. However, anumber of studies have suggested that investing in the maintenance or restoration of natural infrastructurein many cases may not only address given problems at comparable or lower cost than conventional engineering projects, but also generate multiple additional benefits that ultimately translate into cost savings and increased human wellbeing. Meanwhile, great strides have been made in the design of sustainable mechanisms to deal with urban environmental issues, stormwater flows and the attendant pollution problems, and management and planning of cities is increasingly taking a holistic approach that includes the use and conservation of semi-natural and natural areas within cities as part of a green urban development strategy. One of the challenges of green urban development will be to findthe right balance between ecological infrastructure(natural systems), “green” (= environmentally friendly)built infrastructure, and conventional (“grey”) built infrastructure. Dar es Salaam, located on Africa’s Indian Ocean Coast,faces a multitude of environmental problems. Prominent among them is the problem of flooding in and around the city centre, which frequently brings the city to a standstill, as well as causing infrastructural damage. Many factors have contributed to this problem, including unplanned informal settlements in the upper catchment and floodplain areas, a lack of drainage and a lack of solid waste management. The impacts of flooding are also exacerbated by high levels of pollution in the rivers, which increases the risks associated with flooding. In consultations for this study, stakeholders in Dar esSalaam identified the Msimbazi River as being amongthe most degraded ecosystems in the city and also the source of the most serious flooding problems. The aim of the study was to explore the potential costs and benefits of undertaking a green urban development approach, including catchment-to-coast restoration measures, to ameliorate flood risk in the Msimbazi Rivercatchment.
Turpie, Jane; Kroeger, Timm; De Risi, Raffaele; de Paola, Francesco; Letley, Gwyneth; Forsythe, Katherine; Day, Liz. 2017. Return on Investment in Green Urban Development: Amelioration of Flood Risk in the Msimbazi River Catchment, Dar Es Salaam, Tanazania. Promoting Green Urban Development in Africa;. © World Bank, Washington, DC. License: CC BY 3.0 IGO.
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