EXTRACTION OF INUNDATED AREA DUE TO 2011 THAILAND FLOOD USING U-NET TO COSMO-SKYMED IMAGES

Abstract

 Rapid response to natural hazards, such as floods, is very important to establish an initial response system. Therefore, it is expected to establish a disaster investigation method using synthetic aperture radar (SAR) data that can be observed even in cloudy weather or at night. However, the conventional threshold method has low accuracy in inundated area extraction. In this study, inundated area extraction using U-Net on preand post-event COSMO-SkyMed images were performed for the flood in Ayutthaya, Thailand in 2011. The accuracy was evaluated by comparing with a reference map derived from Terra/ASTER NDWI images. As a result, the F-measure was 92.0% in the inundation area extraction by U-Net using the three layers of the pre-event, post-event and the difference between pre- and post-event COSMO-SkyMed images. The F-measure of the U-Net was superior to those of the threshold method. In conclusion, the U-Net is more effective than the threshold method for inundated area extraction using X-band SAR images.