SWMM Sensitivity to LID Siting and Routing Parameters: Implications for Stormwater Regulatory Compliance

摘要

Cities are experiencing new growth through infill development, or "redevelopment," where lower density land uses are redeveloped to high density with increased impervious surfaces. Cities need revised stormwater criteria to manage increases in stormwater runoff and flooding from redevelopment via low impact development (LID). Watershed-scale hydrologic modeling in the Storm Water Management Model (SWMM) can help policy makers revise regulations to adapt to redevelopment. However, LID modeling is still relatively new and the understanding of model sensitivity to certain parameters is lacking. In particular, LID siting and routing parameters such as outflow routing from, area treated by, and placement of LID are not well studied. Using a case study of a redeveloping neighborhood in Denver, Colorado, we tested 32 configurations of these parameters in a calibrated, SWMM for PC (PCSWMM) model. We found some configurations lead to counter-acting model processes that result in similar runoff reduction across a variety of configurations, suggesting to policy makers that reduction targets may be met in a myriad of ways. The relative sensitivity of runoff volume to area treated and LID placement was found to be on average 3.0 and 11.2 times higher than other model parameters. Given this sensitivity, practitioners and modelers should consider LID siting and routing parameters in hydrologic modeling efforts that inform regulations.