The U.S. Army Corps of Engineers Hydrologic Engineering Center’s River Analysis System two-dimensional (HEC-RAS 2D) modeling is the industry standard in two-dimensional flood inundation modeling. However, HEC-RAS 2D is not designed with modeling of urban stormwater systems in mind. To overcome this limitation a methodology using HEC-RAS 2D pump stations, the U.S. Environmental Protection Agency’s Storm Water Management Model (SWMM) and python scripting was developed. In this model HEC-RAS 2D was used to model the hydrology, surface flow, flood inundation, and stormwater structure hydrographs, and SWMM was used to model the flow through the storm sewer pipes. Python scripting was used to write the hydrographs from the HEC-RAS 2D model data to be read by the SWMM model. This methodology is ideal for use in floodplain mapping studies and in developing design hydrographs for urban stormwater structures and systems in situations where a traditional lumped hydrology model may fail to accurately predict the design flows.
