Development and Application of a SWMM-Based Simulation Model for Municipal Scale Hydrologic Assessments

There is growing interest for the installation of green stormwater infrastructure (GSI) to improve control, increase infiltration stormwater, and receiving water body quality. Planning level tools are needed inform municipal scale decisions on type extent GSI apply. Here, a modified methodology developed EPA Storm Water Management Model (SWMM) create SWMM Low Impact Technology Evaluation (SWWM-LITE) that enables assessment control measure (SCM) performance with minimal input data requirements low processing time. Hydrologic outputs SWMM-LITE compared those National Stormwater Calculator (SWC) assess SWMM-LITE. Three scenarios including baseline without SCMs varying were investigated. Across three scenarios, estimates annual average hydrologic (runoff, infiltration, evaporation) within +/−0.1% from rigorously model in City Fort Collins, CO, an evaluation 30 years continuous simulation. Analysis conducted 2 year (y), 10 y, 100 y storm events showed less than +/−2.5% difference between outputs. SWC provided reasonable parameters case study area, but was designed site analyses rather scale. A sensitivity analysis revealed most sensitive primarily consistent complete SWMM. has time can be applied assessing planning decisions.