Using EO to Support Restoration of Sri Lanka’s Tank Cascade Systems
GDA Water Resources worked with IFAD to use Earth Observation based surface water monitoring to guide the restoration and long-term management of Sri Lanka’s tank cascade systems.
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Description
Sri Lanka’s tank cascade systems are essential for irrigation, flood management, and drought resilience, but many reservoirs have lost storage capacity over time due to siltation and infrastructure degradation.
To support restoration planning, the GDA Agriculture activity worked with the International Fund for Agricultural Development (IFAD) Smallholder Agribusiness and Resilience Project (SARP) to analyse satellite-derived surface water data across six districts. Using Earth Observation, the project mapped more than 10,650 water bodies and created a nine-year record of water frequency, seasonality, and surface water extent between 2017 and August 2025.
The analysis helped distinguish between permanent and seasonal water bodies, identify tanks with declining storage performance, and assess how consistently reservoirs retained water over time. Detailed tank-level profiles were also produced for 189 priority tanks, providing historical records of water availability and responses to rainfall variability.
You can find out more about this Case Study on the GDA Impact Sphere: Supporting tank restoration through surface water dynamics