Assessment of long and short-term flood risk using the multi-criteria analysis model with the AHP-Entropy method in Poyang Lake basin

Abstract

China suffers the most serious loss of life and property with the most floods in the world. In this study, a multi-criteria analysis model with the combined analytic hierarchy process and Entropy weight method (AHP-Entropy) was proposed to assess the long and short-term flood risk in Poyang Lake basin, and results were verified by several flood events that happened on July 2020. Considering multi-factors of flood risk, six flood hazard factors (namely, maximum three-day rainfall (RMAX3), annual average rainstorm frequency (RF), annual average rainstorm amount (ARA), drainage density (DD), slope, elevation (DEM)) and four flood vulnerability factors (namely, population density (PD), land use pattern (LUP), GDP, normalized difference vegetation index (NDVI)) were selected and weights of them were derived from the AHP-Entropy method. Results show that PD (0.168), RMAX3 (0.163), LUP (0.146), GDP (0.129), and RF (0.111) play a vital role in the results of flood risk assessment. Spatially, the long and short-term flood risk maps are shown to have similar characteristics with correlation coefficient of 0.9056. Areas with high risk and very high risk account for 19.6% of the total area in the long-term flood risk map and increased to 22.2% in the short-term flood risk map. Overall, the northeastern parts of the Poyang Lake basin are more prone to floods and the flood risk gradually decreases from the Poyang Lake towards the surrounding areas. Verification of the results with Sentinel-1 synthetic aperture radar data shows that the flood risk assessment model has an accuracy of more than 50% in very high risk zones for floods, and more than 90% for high and very high risk floods, which showed that the presented model is reliable in flood risk assessment.