Flood response law of river basin based on idealized concentric circle rainfall generalization method

To study the response law of the flood process in a basin to the uneven temporal and spatial distribution of rainfall, by taking the Yanhe River Basin as the research object, a one-dimensional hydrological model was established based on SWMM, and an idealized concentric circle rainfall generalization method was proposed.That is, the rainfall was set to move in a concentric circle pattern within a basin.By changing the rainfall movement position and path, the runoff process at each typical section was simulated and analyzed.The results showed that: ① Under the rainfall path from northwest to southeast, the peak flow at the basin outlet section increased from 75.97 m³/s to 133.43 m³/s, and the peak emerging time was advanced by 16 hours.The peak flow at each tributary section showed a trend of first increasing and then decreasing.② The rainfall movement path had little effect on the maximum peak flow at the basin outlet section.The maximum peak flow of 133.43 m³/s was generated at position 7 under the rainfall path from northwest to southeast, and the maximum peak flow of 138.17 m³/s was generated at position 2 under the rainfall path from northeast to southwest, with a flow increase of only 3.55%.③ According to the runoff process at each section, the runoff process at the typical sections of the basin was jointly regulated by the spatial distribution of rainfall and the convergence time.The position of the rainfall area determined the rainfall distribution in the basin, and the duration of the convergence time determined the speed of flow convergence in the basin.The research results can provide a reference for the flood risk assessment of rivers.