Storm Water Management Model Climate Adjustment Tool (SWMM-CAT)

Posted on: 8/01/2017 - Updated on: 2/27/2020

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SWMM-CAT allows users to evaluate climate change impacts on stormwater runoff volume and quality, and to explore how the application of various low-impact development (LID) options can be used to alter these hydrological parameters. SWMM provides a spatial and temporal analysis of runoff quality and quantity by dividing basins into multiple sub-catchment areas and analyzing runoff at different time steps. It covers a variety of different drivers that can cause runoff in urban areas, including rainfall, snowmelt, and groundwater percolation, among others, and also allows for mapping and modeling of different sub-catchment drainage system components, including pipes, channels, diversion structures, storage and treatment facilities, and natural channels. These components allow users to examine relationships between total rainfall, runoff, and various routing options at a sub-catchment scale to effectively plan and design stormwater and sewer systems. SWMM also allows users to integrate seven different LID options to explore how LID projects could be used to mitigate stormwater impacts and sewer overflows. These LID options include: permeable pavement, rain gardens, green roofs, street planters, rain barrels, infiltration trenches, and vegetated swales. On top of these standard SWMM functions, the add-in tool SWMM-CAT can be used to evaluate how changes in precipitation, air temperature, and evaporation may affect runoff trends. Users can manually adjust climate factors on a monthly time scale, or use a set of location-specific adjustments generated by the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3), which was used to generate downscaled climate information for the IPCC’s recent report. SWMM-CAT can be used by a variety of practitioners looking to explore vulnerability and management and design options for stormwater systems, combined and sanitary sewers, and other urban drainage challenges in the face of climate change. It can also be used by non-urban entities.

Phase of Adaptation: Assessment, Planning


Land managers, water utility managers, local authorities, planners, policymakers, engineers, scientists



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