Hydrodynamic modelling of flash flood processes in the typical regions in the upper Yellow River basin

Due to global warming, extreme flood disasters have become more frequent, with their impact especially pronounced in the arid and semi-arid regions in the Yellow River basin． This study aims to enhance capability to defend flood disaster in arid regions, with a focus on the Ten-watershed in the upper reach of the Yellow River． The Hydrologic Engineering Center's River Analysis System (HEC-RAS) is used as the main research tool, model simulation results and Sentinel satellite observations are used as the main data sources． Detailed process simulations of typical torrential rain flood events in the area are conducted and their effects on flood event simulations are evaluated． Validation based on Sentinel images shows that the hydrodynamic model can simulate flood inundation with relatively high accuracy． The resolution and quality of the Digital Elevation Model (DEM) are vital for the accuracy of the simulated flood inundation extent． HEC-RAS still has considerable limitations in simulating floods in large basins using high-resolution DEMs and computational grids． It is suggested that the region should strengthen hydrological monitoring efforts to provide ample data support for establishing an integrated flood defense system in the future．