Towards a More Spatially Explicit Stormwater Management Model (SWMM)

Abstract Submission: The United States Environmental Protection Agency’s (EPA) Stormwater Management Model (SWMM) has been an indispensable tool for engineers and researchers doing stormwater and wastewater related studies and infrastructure design since its development about 50-years ago. This presentation will highlight ongoing efforts to provide options for representing the spatial heterogeneity of the hydrologic processes represented in SWMM with an increased degree of fidelity. First, we preview a new GIS-based graphical user interface being developed to enhance SWMM’s ability to integrate standardized and increasingly ubiquitous GIS data formats, including web map tiled services (WMS and WMTS) and various raster and vector data formats. The benefits of these integrations are manyfold and include providing the spatial context and setting for modeling studies through displaying basemaps; delineating model boundaries, connectivity, and alignments of collection system infrastructure; and for parameterizing hydraulic and hydrologic processes. Second, we will preview a new coupled overland and groundwater flow component that employs a semi-discrete finite-volume method that is patterned after the Penn State Integrated Hydrologic Model. This model is being developed as an option to better support integrated modeling applications seeking to look at critical feedback loops that are increasingly important considerations for finer scale analysis and design of resilient collection systems given the uncertainty about future urban growth and climate. With these implementations, critical hydrologic, hydraulic, and water quality process representations and feedback loops including, effect of spatially varied gridded rainfall data on runoff generation; evapotranspiration partitioning; coupling between piped/channel flows with overland flows; coupling between groundwater and surface water flows; assessing aggregate impacts of green infrastructure and nature-based solutions can be represented for more targeted planning.

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