Extract Surface Water Features From Sentinel 1 Data Using ESA SNAP

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Surface water body data like Lakes, Ponds, Reservoirs, Rivers are important geospatial data for many purposes. This kind of data can be obtained in many ways. They can come from field measurements, GPS-based measurements, or derived from Aerial Photographs or Satellite Imagery. Deriving surface water features from aerial photographs or satellite imagery, in particular, has some strength compared to more conventional mapping methods. Aerial Photographs or Satellite Imagery recording the surface water body in a synoptic way. It s is basically just like the real features that we saw in the field. It is also efficient and time-saving. You can get the data either in vector format or raster format depends on your preferred extraction methods. 

Particularly for satellite imagery, these data could come from a wide range of imaging sensors operates in different electromagnetic spectrum (from optical spectrum to radar/microwave spectrum). Different spectrums will expose different characteristics of the water surface features, so you have various options to get the water surface features data. 

One benefit about water surface features extraction using data coming from radar / SAR sensors is free of cloud cover, so you can get water surface features or water body information on any weather conditions. Even if your area of interest got struck by hurricanes, heavy rains, or any other bad weather at your target date, you still can get a pristine and clear view of the area. This is something that you can't get from optical imagery because at these conditions, optical imagery will show none but thick and widespread clouds. You can also monitor the water surface features at flooding conditions. This is why many agencies or mapping companies are using SAR data to get water surface features data. 

Water surface feature extraction from SAR Imagery is a little bit different compared to methods commonly used in Optical Imagery. In optical imagery, you can use extraction methods like NDWI index or image classification, but these methods are not working for SAR data. Regarding this matter, I already made a video tutorial below about how to extract surface water features from SAR data, using Sentinel-1 data that available to download for public use. Check this out below.


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