Open kleok opened 1 year ago
The pre-flood water extent will be extracted by Sentinel-1 imagery and Sentinel-2 images before the flood.
We select only recent (last month) Sentinel-1 acquisitions that are not related to "big" precipitations events. We calculate the median backscatter coefficient over time. We download a third-party dataset for water extent (e.g. JRC) We create a buffer zone of the water extent We calculate threshold (e.g. Otsu) and apply at median backscatter coefficient
We select only recent (last month) Sentinel-2 acquisitions with low cloud coverage (< 10%) We calculated MNDWI and apply cloud masks We calculate the median MNDWI values over time. We calculate a suitable MNDWI threshold at the buffer zone. We can have a look here. We apply thresholding at median MNDWI values.
The final map is calculated as the union of Sentinel-1 and Sentinel-2 water masks
The pre-flood water extent will be extracted by Sentinel-1 imagery and Sentinel-2 images before the flood.