Green Stormwater Infrastructures (GSI) are an effective way of mitigating the adverse effects of urbanization and are commonly used for frequent rainfall events. Increasingly, we are observing that GSI also plays a role in mitigating flooding during extreme events. Within the USEPA SWMM and PCSWMM modeling software, GSI are commonly modeled as Low Impact Development (LID) or Storage Units (SU). The present research focuses on the performance of a multiple GSI system alongside student housing at Villanova University. The University converted a nine-acre parking lot into student dorms using innovative techniques to offset the negative effects of urbanization by incorporating a combination of sixteen distinct GSI. These interconnected GSI were modeled as a system in PCSWMM, and their performance was assessed. Each GSI was modeled through the Low Impact Development (LID) module, with infiltration simulated through the Green-Ampt equation, which considers water depth, soil porosity, suction head, and saturated hydraulic conductivity. The model was calibrated using the SRTC (Sensitivity based Radio Tuning Calibration) tool by comparing continuously collected observed data from the field at 5-minute intervals. The model was used to forecast how the entire system would respond to potential extreme events, as well as to evaluate and contrast the model from the pre-construction phase in terms of peak flow and runoff volume reduction. Preliminary results show that peak flow rates during hurricanes are reduced by approximately 70% and the outflow runoff volume was reduced by approximately 45%. With the use of this model, we can better plan for including GSI in flood management and resilience design.
