DETECTING DISASTER DAMAGE FROM 2015 TYPHOON ETAU BY THE COMBINED USE OF DIFFERENT SAR SATELLITES

Abstract. In this study, focusing on the flood damages in Joso City in Ibaraki Prefecture, we estimated the extent of inundation using multiple SAR satellites and examined their varied results depending on observational bands. We further examined the potential utilization of combined different SAR data for initial responses to disasters. For classification of the inundated areas, a binary classification was used with a threshold of backscatter coefficient and the difference in backscatter coefficient between the usual condition and the situation after the breach. In the extraction of inundation after the breach of the levee, COSMO-SkyMed showed the accuracy of 72.6%, while ALOS-2 PALSAR-2 indicated the accuracy of 66.1%. The extent of inundation were extracted by difference of backscatter coefficient using the data taken by Sentinel-1 and ALOS-2 PALSAR-2 before the breach of the levee, and the comparison analysis results showed that the extent of inundation expanded after the breach of the levee. From the above results, we graded the characteristics of the satellites by their observational bands and spatial resolution.