Study on urban flood simulation based on a novel model of SWTM coupling D8 flow direction and backflow effect

Abstract

Urban flood is a serious challenge that increasingly affects the residents. Simulation of urban flood is becoming increasingly relevant in the world. However, how to improve the simulation accuracy is still a challenge in the field. This paper is developed to propose a novel model of SWTM (SWMM model and TELEMAC-2D model) coupling D8 flow direction and backflow effect, improving the simulation accuracy of inundation area, inundation depth and inundation duration. The model is organized into three parts: one-dimensional pipe network model establishment, two-dimensional surface inundation model, and coupling model SWTM construction. The D8 algorithm is introduced to subcatchment division. The linear interpolation in DEM is applied to improve the accuracy of D8 algorithm. It enables more accurate simulation of rainfall runoff processes using the path weighted average method for the calculation of feature width and feature slope in watershed. The overflow and backflow effect of inspection wells are both considered to simulate the flood inundation in the two-dimensional surface inundation model, which can obtain the maximum inundation depth and inundation area more accurately. In the coupled model, the overflow and backflow process of inspection wells are used as the input condition of the two-dimensional model to simulate the flooding process. The new model is applied to rainstorm waterlogging in Fangzhuang area, Beijing. It shows that SWTM model can simulate the changes of inundation range, inundation depth and inundation duration more accurately comparing with the traditional model.