TechnicalGIS

Is there still water at this pan, dam or pond?

Mark a pan, dam or pond and we'll tell you how much open water it held in the latest clear satellite image, how that compares with the same month in other years, and whether it's filling or drying. It takes about a minute.

1. Mark the place

Latitude first, as in 3.1194, 35.5973. Copy it from Google Maps or OpenStreetMap, use your phone's location, or tap the map.

2. Or find it on the map (optional)

Mark the place first.

Usually ready in about a minute. Free, up to 15 new questions a day each; answers we've already worked out are instant and don't count. Privacy.

Choose a country to see its districts, then tap the map to mark the place.

District boundaries from geoBoundaries, simplified for the web.

See all the community tools, or Farm check for one farm.

How it works

  1. Images. We look at every Sentinel-2 image since 2017 and, for each month, keep the clearest one that covers the circle around your point.
  2. Water. A 20 m square counts as open water when it is brighter in green light than in short-wave infrared light, which water absorbs. This is the modified normalised difference water index (MNDWI). Cloud and cloud shadow are left out, and a month is used only if at least 80% of the circle is clear.
  3. Usual. We compare the water now with the same month in every other year, and with the most the point has held.

It sees open water bigger than a few 20 m squares. Water hidden under reeds or trees, and very shallow mud, can be missed, and a borehole or covered tank can't be seen at all.

You get a short answer with the big numbers, a one-page sheet to print, a text message you can copy or send on WhatsApp, and the figures as a spreadsheet (CSV).

Official sources

We check the satellite record. For warnings and advice, go to the people whose job it is:

  • FEWS NET : food security and water outlooks for pastoral areas.
  • NDMA Kenya : county drought bulletins, which report water at pans and dams.

Data and credits

Licences checked on each provider's own page, last on 29 October 2026.

SourceLicenceCredit
Copernicus Sentinel-2 Level-2A imagery Copernicus Sentinel data legal notice (free, full and open use, including commercial) Contains modified Copernicus Sentinel data 2017–2026, accessed through Microsoft Planetary Computer.
geoBoundaries administrative boundaries Per country (CC BY, ODbL or open government licence) Runfola, D. et al. (2020) geoBoundaries: A global database of political administrative boundaries. PLoS ONE 15(4): e0231866.

Questions

Which water points work best?
Pans, dams, ponds and lake edges with at least a few hundred square metres of open water. Choose a smaller circle for a small pan so that nearby rivers or fields don't get counted.
Why is there no figure for some months?
Clouds. If no image that month was at least 80% clear over your water point, we leave the month out rather than guess. Radar would see through cloud, but it can't pick out small pans reliably.
Why not use the JRC Global Surface Water maps?
They are excellent for history but end in 2021. Sentinel-2 lets us tell you about this month.
Can I use the answer in a report?
Yes, in reports, funding bids, meetings and on notice boards. Keep the line "Generated at TechnicalGIS.com" and the data credits. Each answer has its own link and is kept for 90 days.

See real answers for real places, all the community tools or read what we're for. Need it for a whole region or every month? Talk to us.