Inundation simulation for urban drainage basin with storm sewer system

An urban inundation model, combining a storm sewer model SWMM, two-dimensional (2D) diffusive overland-flow model and operations of pumping stations, has been developed to simulate inundation in urban areas caused by the surcharge of storm sewers and outlet pumping stations. The movement of water in the studied urban watershed is characterized by two components, namely, the storm sewer flow component and the surcharge-induced inundation component. SWMM is employed to solve the storm sewer flow component and to provide the surcharged flow hydrographs for surface runoff exceeding the capacity of the storm sewers. The 2D diffusive overland-flow model considering the non-inertia equation with Alternative Direction Explicit numerical scheme is then used to calculate the detailed inundation zones and depths due to the surcharged water on overland surface. Drainage by pumping stations at outlets of the storm sewer system has also been taken into consideration. The parameters of the model are calibrated and verified for discrete storms. The combined model is suitable for analysis of inundation on urban areas due to overflow of storm sewers and flooding caused by failure of pumping stations. Simulated results can be applied to establish flood-mitigation measures.