Abstract: Flood disasters are highly frequent and strongly destructive. Risk assessment reveals high-risk hotspots and their driving factors, aiding in the establishment of a scientific and efficient flood control and disaster reduction system. This study focuses on the Xunjiang Flood Control Protection Area in the Pearl River Basin. Initially,the HEC-RAS hydrodynamic model was constructed to extract maximum flow velocity and water depth for flood risk evaluation. Subsequently, the exposure and vulnerability of affected populations were assessed by using the AHP and entropy weight methods in consideration of factors including population density, GDP, and land use. Finally, flood risk was quantified, and spatial-temporal changes were analyzed. Results indicate that the hydrodynamic model achieves an average accuracy exceeding 0.80, with a false positive rate below 0.28. Medium to high-risk zones in the Xunjiang Flood Control Protection Area exceed 5.20%. From 1997 to 2017, risks of various levels displayed an increasing trend. Notably, nearly 46.69% of medium to high-risk zones exhibited significant upward trends. These findings support informed decision-making in flood risk management practices.

Key words: flood risk assessment, flood inundation, hydrodynamic simulation, flood control protection area, evolution law, Pearl River Basin