“…A collection of studies for mapping floodwater have been explored using the data from various SAR sensors, such as ALOS-PALSAR [6], Sentinel-1 [7], Radarsat-2 [8], TerraSAR-X [5], and COSMO-SkyMed [9], reflecting the usefulness and activeness of this research field. On the other hand, due to the side-looking nature of such sensors, SAR data suffers from the effects of corner reflection [10], double bounce [11], layover, and shadowing [5], which still pose challenges to detecting floodwater in urban areas [12]. In the meantime, multispectral optical imagery from various satellite sensors such as Landsat [13], Sentinel-2 [14], PlanetScope [15], SPOT-5 [16], and Worldview-2 [17] is another widely used data source for flood mapping owing to its abundance of spectral information and global coverage.…”