Real data
SWOT readings for our five reservoirs
Every best-quality SWOT reading from July 2023 to October 2026, straight from NASA's Hydrocron service. Pick a reservoir to see its water level and how much water it stored.
Water level
Metres above sea level. Each dot is one best-quality SWOT reading.
Water stored above the lowest reading
Million m³, from SWOT's own storage-change numbers. This is the water above the lowest level SWOT has seen, not the whole tank.
All readings as a table
| Date | Water level (m) | SWOT water area (km²) | Stored above lowest (million m³) |
|---|
How to read this
What these numbers can and cannot tell
Best quality only
We keep a reading only if SWOT's quality flag is 0, its crossover flag is 0 or 1, and at most 10% of the lake is "dark water" (Köhn and Nielsen, 2026).
Change, not the whole tank
SWOT's storage numbers show how much water came and went. How full a tank is also needs the water below SWOT's lowest reading, from the Irrigation Department's capacity tables.
Not yet checked
Nobody has checked SWOT's storage numbers against Sri Lankan gauges. Doing that, and building our own curves, is the core of our project.
Data made on from NASA PO.DAAC's Hydrocron (SWOT Lake Single-Pass product, version D). Official capacities: Irrigation Department, Reservoir Status, 25 Oct 2026. You can also see SWOT readings for any lake on the public SWOT Lake and River Explorer.