A multi-level and modular model for simulating the urban flooding and its application to Tianjin City

Abstract

In this study, we present a multi-level and modular model for urban flood. It consists of four modules which simulate: (1) two-dimensional (2D) flow routing on communities, (2) 2D flow routing on road networks, (3) 2D flow routing on river network, and (4) one-dimensional (1D) flow routing on sewer system. The four modules are coupled by pumping stations, gutter inlets, and procedures. The gates or pumping stations connect the sewer system and the river network, allowing volume exchange between underground pipes and river network. The gutter inlets connect the sewer system and the river network, allowing volume exchange between the road network and underground pipes. The consistent treatment has also been included between the community areas and sewer system. The coupling among the four modules not only captures the interaction between surface and subsurface components, but also divides the surface open channels into community areas flow, road network flow and river network flow. Therefore, it greatly improves the calculation efficiency and accuracy. A catchment in Hexi District of Tianjin City, China, is used as the study case to validate the model. The simulated results agree well with the measurements in the following four aspects: the water levels of the Jin River, water depth at feature points, waterlog conditions in two important areas, and water balance. This model, which greatly improves the simulation of the dual drainage system, can be very useful for future prediction and identification of urban flooding.