Establishment of urban flood simulation model for Chebeichong River in Guangzhou City

Abstract

[Objective] In the context of global climate change, rapid urbanization has a profound impact on hydrological processes, and complex urban underlying surface has brought challenges to the calculation of runoff generation and flow concentration. There is an urgent need to develop urban flood simulation technologies that comprehensively consider different underlying surface conditions. [Methods] Based on the characteristics of runoff generation and flow concentration and land use types, the complex urban underlying surface was classified into permeable, directly impervious, and indirectly impervious surfaces. The runoff generation was calculated using the saturation-excess, infiltration-excess, and API-SCS-CN method, respectively. Combined with the flow concentration of slopes, pipelines, and river channels, Chebeichong urban flood simulation model was established for the Chebeichong River Basin in Tianhe District, Guangzhou. The model's practicality, considering the complex underlying surface, was validated using the measured rainfall and runoff data from 2021 to 2023. [Results] During the calibration period, the Chebeichong urban flood simulation model achieved a Nash efficiency coefficient of 0.71 and a correlation coefficient of 0.74 for flow simulation. During the validation period, the Nash efficiency coefficient reached 0.79, and the correlation coefficient reached 0.81. Under the same modeling conditions, the SWMM-SCS model achieved a Nash efficiency coefficient of 0.5 and a correlation coefficient of 0.6. [Conclusion] The simulation result of the Chebeichong urban flood simulation model are more accurate than those of the SWMM-SCS model, with the Nash efficiency coefficient improving by 66.7%, the runoff correlation coefficient increasing by 29.7%, the flood volume error decreasing by 48.3%, and the peak flow error decreasing by 3.2%. These findings indicate that incorporating complex underlying surfaces and multiple runoff generation models enhances the reliability and applicability of urban flood models, providing a new approach for urban flood simulation.

Keywords

rainfall / complex underlying surface / urban flood simulation / runoff generation and flow concentration / API-SCS-CN / Chebeichong River