Publication: Estimating Transient Freshwater Lens Dynamics for Atoll Islands of the Maldives
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Published
2014-07
ISSN
0022-1794
Date
2016-05-17
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The water resources of the atolls of the Republic of the Maldives are under continual threat from climatic and anthropogenic stresses, such as changing rainfall patterns, sea-level rise, and contamination from human activities and climatic events. Groundwater, a historically important resource of the island communities of the Maldives, is particularly affected due to the fragile nature of the freshwater lens on small atoll islands. In this study the dynamics of the freshwater lens are simulated during an extended (1998–2011) time period to determine the fluctuation of lens thickness of islands of the Maldives in response to annual and long-term changes in rainfall. Particularly, maximum and minimum lens thickness during the simulation period are assessed, as well as the occurrence of general trends, either decreasing or increasing, in lens thickness. Simulations are performed for a variety of island sizes, corresponding to the range of sizes of the islands of the Maldives, and for the various climatic regions of the Maldives. Results indicate that many of the atoll islands are expected to have a measurable freshwater lens during the majority of a long-term climatic period, although significant decreases in thickness can occur during the months of the dry season, with complete depletion occurring for small islands. Of particular note is the observation of a general decrease in lens thickness, approximately 2–4 cm/yr, over the 14-year period for the northern regions of the Maldives. If continued at current rates, these trends can have a significant impact on groundwater resources for the Maldives. Results imply that fresh groundwater, if properly protected from land surface-derived contamination and over-pumping and associated salinization, can be a valuable source of water for the Maldives, particularly for the larger islands. Overall, results provide water resource managers and government officials with valuable data for consideration in water security measures.
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Publication Estimating Current and Future Groundwater Resources of the Maldives(Wiley, 2015-02)The water resources of the atolls of the Republic of Maldives are under continual threat from climatic and anthropogenic stresses, including land surface pollution, increasing population, drought, and sea-level rise (SLR). These threats are particularly acute for groundwater resources due to the small land surface area and low elevation of each island. In this study, the groundwater resources, in terms of freshwater lens thickness, total volume of fresh groundwater, and safe yield are estimated for the 52 most populous islands of the Maldives for current conditions and for the year 2030, with the latter accounting for projected SLR and associated shoreline recession. An algebraic model, designed in previous studies to estimate the lens thickness of atoll islands, is expanded in this study to also estimate volume of groundwater. Results indicate that average current lens thickness, groundwater volume, and per capita safe yield are approximately 4.6 m, 1,300 million liters, and 300 l/day, and that these values will decrease by approximately 10, 11, and 34%, respectively, by the year 2030. Based on results, it is demonstrated that groundwater, in terms of quantity, is a viable source of water for the islands of the Maldives both now and in coming decades, particularly for islands with large surface area and low population. Study results can provide water resource managers and government officials with valuable data for consideration in water security measures. 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