The map shows river basins (or river reaches) coloured according to their estimated rate of annual surface water change. The colour legend appears on the bottom-left of the map panel. 

Use the "Seasonality of water" selector on the left panel to switch between permanent or dry or wet season water. Use the "Scale of aggregation" selector on the left panel to switch between river basins or reaches. 

Click on a basin (or a reach/transect) to plot its historical timeseries of surface water area. The point of click and the corresponding basin (or transect) selected will appear highlighted in green. The time series chart will appear on the bottom-right of the map panel. This step can be slow depending on your internet speed, so allow a few moments for the charts to load. 

The second chart that appears along with the surface water area chart, shows the corresponding timeseries of proportion of area with no valid data. A high value of this proportion indicates less confidence in the corresponding surface water area estimate. Time-points with no-data proportion greater than 0.05 (i.e., 5% of total area) are, for the purpose of this analysis, deemed to be invalid due to data inadequacy and hence dropped from trend estimation.

See our Methods for more details.

Download season-wise timeseries of surface water area of a few basins or transects you select. 

Note: Use this is for relatively small downloads (a few basins or reaches at a time). To access the time series for our entire set of basins or reaches, see here for how to do so from cloud data assets within Google Earth Engine.

First, switch to the map app's download mode by checking the the "Download raw data" box on the left panel. This will allow you select a few basins or reaches (whichever was selected when switching to the download mode) and download their area time series.

1. Zoom and/or pan to your basin/s (or transect/s) of interest.

2. Click on the polygon icon (▱) on the map panel's top-left to start drawing polygons. A "Geometry Imports" panel appears on the top-left, where all your drawn polygons are gathered.

3. Use your mouse to draw polygon/s to select features of your interest. 

   • Single-click to start or continue drawing a polygon

   • Double-click to finish a polygon

   • To edit a previously drawn polygon:

     1. Click on the polygon's layer under "Geometry Imports" to select it on the map.

     2. Click on the selected polygon on the map. Its vertices are highlighted to indicate that it is ready to be edited.

     3. Click-and-drag a highlighted vertex to move it.

All the features the drawn polygon intersects with are taken to be selected and are highlighted in yellow. In case your features of interest cannot be selected using a single polygon, you can draw separate polygons to select them in one go, or select and download them separately.

4. Once your features of interest are selected, click on the "Start data download for selected regions" button in the left panel to initiate a download. Wait a few moments while your download request is processed.

5. When the drawn polygon/s yield a valid selection of features, a link appears below the "Start data download ... " button called "Click here to download file". Click on this link to start your CSV download.

   • If the selection is invalid, such as when the drawn polygons do not include any features, a "Invalid selection, probably because no valid features got selected for download. Use the polygon drawing tool to select features." message appears instead of "Click here ...". In this case, edit/redraw your polygons and try again.

Note: To switch between basins and reaches for downloading a CSV file, first uncheck the "Download raw data" box on the left panel to exit the download mode, and then use the scale of aggregation selector to switch.