Rapid simulation of urban rainstorm flood based on WCA2D and SWMM model

This study attempts to combine the cellular automata inundation model (WCA2D) with SWMM (SWMM/WCA2D) to explore the mechanism and computational efficiency of WCA2D coupling the traditional one-dimensional pipeline network model. For this purpose, we developed a rapid flooding simulation technology with the Changban catchment (a typical catchment features complicated in Guangzhou) as a study case. By comparing with the measured inundation data and the simulation results performed by SWMM/LISFLOOD-FP model, we could obtain the following results:the simulation results are close to measured inundation data related to the "20180607" rainstorm, suggesting that the coupled model presents good precision. According to the results of model precision indices, the scenario considering the blockage of main pipe and buildings shows the highest simulation precision with the R_TPR, R_PPV and F₁ of approximately 0.8, 0.6 and 0.7, respectively, which best characterizes the actual conditions of the study area. By coupling with SWMM, the simulation results of WCA2D and LISFLOOD-FP shows little difference (the maximum depth difference lower than 0.1 m) and higher correlation (the correlation coefficients almost larger than 0.7), however, the computational efficiency of WCA2D is 3-5 times higher than that of LISFLOOD-FP, indicating that the WCA2D could be feasibly and effectively combined by SWMM. Therefore, the coupled model (SWMM/WCA2D) proposed by this study could provide a novel way to implement rapid urban flooding simulation in the complicated urbanized areas.