Flood maps of historical flood events (Panaro)

Flood maps calculated from space-borne remote sensing Synthetic Aperture Radar (SAR) VV backscatter data during the extreme hydro-meteorological events occurred along the Panaro River . Sentinel 1/TerraSarX SAR data has been processed by a method combining thresholding and segmentation (CThS method). The main idea of CThS is to find some samples which are definitely seeds of the flood water areas. In doing so, a statistical measure of randomness, i.e. entropy filtering, is applied to characterize the texture of the input image. It tries to find locally some pixels, which contain the entropy values of the 3-by-3 neighborhood around the corresponding pixel in the input image. What the local filtering identifies is areas with a significant difference with the surrounding areas. These areas could contain different ground targets, which have the same signature as water. Then histogram thresholding is performed. The histogram of all pixels extracted by filtering is reasonably bimodal so that a suitable threshold value can be determined by fitting a curve to the histogram to separate water and non-water pixels. Having separated water seed points, an active contour segmentation method is used to delineate the full flood extent. The dataset contains flood maps for the dates: 12 and 13 December 2017 and water maps on 20 January 2014 and 8 December 2020.