Urban inundation response to rainstorm patterns with a coupled hydrodynamic model: A case study in Haidian Island, China

With rapid urbanization, rainstorm-induced inundation losses are becoming increasingly severe. Research on urban inundation response to rainstorm patterns can help engineers and governments make appropriate decisions and mitigate property losses. This paper introduces a new hydrodynamic model that couples the storm water management model (SWMM) and the shallow water model (SWM) and applies the validated model to the Haidian Island case to determine the inundation response to rainstorm patterns. The results show that the coupled model can predict rainstorm-induced inundation well, and that different rainstorm patterns would result in different inundation patterns. With increasing rainstorm peak position coefficients, urban inundation events become more severe and inundation peaks appear sooner. However, the times at which inundation occurs do not change. To determine the reasons for the differences in inundation among different rainstorm patterns, correlations between the inundation volume and the fully-filled pipes ratio were analyzed. Correlation analysis showed that inundation events are significantly related to the working state of the sewer system, indicating that a higher fully-filled pipes ratio prior to the rainstorm peak will result in more severe inundation. This conclusion suggests that the range of rainstorm peak position coefficients in China is quite reasonable. This result can provide insights to engineers and the government for urban design planning and maintenance.