LAUSR

Abstract Summer floods occur frequently in many regions of China, affecting economic development and social stability. Remote sensing is a new technique in disaster monitoring. In this study, the Sihu Basin in Hubei Province of China and the Huaibei Plain in Anhui Province of China were selected as the study areas. Thresholds of backscattering coefficients in the decision tree method were calculated with the histogram analysis method, and flood disaster monitoring in the two study areas was conducted with the threshold method using Sentinel-1 satellite images. Through satellite-based flood disaster monitoring, the flooded maps and the areas of expanded water bodies and flooded crops were derived. The satellite-based monitoring maps were derived by comparing the expanded area of images during a flood disaster with that before the disaster. The difference in spatiotemporal distribution of flood disasters in these two regions was analyzed. The results showed that flood disasters in the Sihu Basin occurred frequently in June and July, and flood disasters in the Huaibei Plain mostly occurred in August, with a high interannual variability. Flood disasters in the Sihu Basin were usually widespread, and the affected area was between Changhu and Honghu lakes. The Huaibei Plain was affected by scattered disasters. The annual mean percentages of flooded crop area were 14.91% and 3.74% in the Sihu Basin and Huaibei Plain, respectively. The accuracies of the extracted flooded area in the Sihu Basin in 2016 and 2017 were 96.20% and 95.19%, respectively.