Hydrological reduction and control effect evaluation of sponge city construction based on one-way coupling model of SWMM-FVCOM: A case in university campus.

The exacerbation of global warming, the frequent incidence of extreme weather events, and the rapid urbanization have collectively contributed to the heightened prevalence of flooding in urban areas. As a result of this challenge, sponge city (SPC) has been adopted in China as an efficient means of preventing and controlling urban floods. To evaluate the hydrological reduction and control effect of sponge city construction (SPCC) within a university campus, a one-way coupled model integrating one-dimensional sewer hydrodynamic model (SWMM) and two-dimensional surface flow model (FVCOM), namely SWMM-FVCOM model, was established. The Nash-Sutcliffe efficiency (NSE) of the SWMM were greater than 0.75 under there rainfalls with different intensity, indicating the good reliability and stability of this model could be used in the subsequent simulation. An analysis of drainage capacity and the risk of urban flooding was conducted using this model before and after the implementation of SPCC, considering six rainfall scenarios. Implementing SPCC demonstrated an effective performance in mitigating surface runoff, regulating inspection well overflow, and reducing overflow volume in the study region. However, the efficacy of runoff control diminished proportionally with the escalation of rainfall return period. Simultaneously, the implementation of low impact development (LID) measures can significantly decrease the extent and magnitude of surface inundations. The reduction rate of SPCC on the area of waterlogging ranged from 55.84% to 72.50%. But the control rate decreased with increasing rainfall return periods, demonstrating that adopting SPCC can effectively mitigate the severity of urban flooding resulting from low rainfall return period events (Tr < 20 years). This study can provide scientific foundation for environment managers to evaluate the impact of urban flooding prevention and control on runoff pollution mitigation when adopting the implementation of SPCC.