MODELING URBAN FLOODING IN THE TIBER BRANCH WATERSHED, ELLICOTT CITY, MARYLAND, USING PCSWMM

Abstract

Urban flooding — due to land cover change, inadequate drainage networks, and increased precipitation — exacerbates communities’ economic and social vul¬nerabilities. A detailed watershed model can help communities identify weak portions of the drainage network and design resolutions. This research details the development of a comprehensive model of the Tiber Branch Watershed in Ellicott City, Maryland, to reproduce observed depth in the Hudson Branch tributary using PCSWMM (a commercial version of the U.S. Environmental Protection Agency’s Storm Water Management Model). The 2,434.8-acre watershed comprises 8,821 PCSWMM objects, which were estimated from various raster and vector datasets. Without calibration, the model generally captures the timing and shape of the stage hydrographs but is less successful in simulating event magnitude and receives a R2 of 0.65 and SE/SY of 0.67 for the 43 selected events, collectively. Ultimately, model evaluation was not completed due to a lack of representative rainfall within the watershed.