HYDRAULIC MODELS FOR MACROSCOPIC URBAN FLOOD SIMULATION AND ECOLOGICAL ASSESSMENT

Large scale flood simulation in urban areas remains time consuming when applying finer grids which describe the feature of buildings and other structures. The terrain information would be lost when resampling fine grids into coarse grids such that the modeling results may not reflect the reality of flow propagation properly. This paper intends to solve this dilemma with the shallow water equations modified by introducing extra parameters to account for the reduction in storage and conveyance due to the existence of buildings. To reflect the key feature of grids separated by a building inside, one single coarse grid cell may have two or more porosity parameters applied to calculate the flow path. The modified shallow water equations would be coupled with convective-diffusion equation to simulate the transport and distribution of pollutants in flood events. We applied the new model to two case studies and the results show the proposed model has significant improvement in both the computing cost and accuracy.