2D numerical modeling of two dam-break flood model studies in an urban locality

Abstract

The increasing frequency of urban flooding episodes is a cause for concern for urban management and deciders. In this research, two benchmark urban flood inundation modeling (FIM) studies under the European Union-funded IMPACT Project are modeled with the 2D Sedimentation and River Hydraulics model, SRH2D. The two studies are “the model city flooding experiment” and the “isolated building” test case. The model result comparison with the measured datasets are carried out in terms of time series of flow depths at gauge locations as well as the surface flow velocity maps over the whole domain. The model is also assessed for different building treatments in the computational mesh. The model performed admirably in reproducing the flow depths at the gauge locations with a mean Nash-Sutcliffe efficiency value of 0.89. The model discrepancy is mostly due to 3D effects, which are predominant, right after the dam-break flow release from the reservoir. The second case study investigates dam-break flow around a single building as opposed to the first case study, which is focused on a locality exposed to flood. The study points to the promise held by the 2D shallow water equation-based FIM models in tracking the flood progression and providing a reliable spatiotemporal numerical dataset for the flow depths and discharges, which is a key ingredient that goes into the generation of flood hazard maps.