Season-wise timeseries of surface water area, for basins and transects, can be downloaded in CSV format directly from the trends visualization app. Use its data downloading functionality to select a few specific basins or transects to download the data for.
Note: Due to limits on backend processing loads, requests for very large file downloads may fail. If this happens, try reducing the download size by reducing the number of features selected. While it is hard to predict, as a thumb-rule, download sizes upto 32MB should usually work.
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.
Zoom and/or pan to your basin/s (or transect/s) of interest.
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.
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:
Click on the polygon's layer under "Geometry Imports" to select it on the map.
Click on the selected polygon on the map. Its vertices are highlighted to indicate that it is ready to be edited.
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.
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.
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.
The CSV file has the following columns.
HYBAS_ID or txId (string): feature's unique identifier
HYBAS_ID is for basins. It is the same as the basin's identifier HYBAS_ID in the HydroBASINS dataset
txId is for transects. It is the '_' concatenated string derived from the longitude and latitude values, truncated to 4 decimals, of the transect's median point. Specifically, it is "xx.xxxx_yy.yyyy" where xx.xxxx and yy.yyyy are the median's longitude and latitude values truncated to 4 decimals.
area_ha (float): feature's area, in hectares
year (float): year
dry_fma_water_ha (float): Area of water pixels in the feature in the dry season water composite image, in hectares.
dry_fma_nodata_ha (float): Area of nodata pixels in the feature in the dry season water composite image, in hectares.
wet_ond_water_ha (float): Area of water pixels in the feature in the wet season water composite image, in hectares.
wet_ond_nodata_ha (float): Area of nodata pixels in the feature in the wet season water composite image, in hectares.
prm_DnW_water_ha (float): Area of water pixels in the feature in the permanent water composite image, in hectares.
total_nodata_ha (float): Area of nodata pixels in the feature in the permanent water composite image, in hectares.