Storm Water Management Model Gets Climate Update

By Marguerite Huber

Image of a flooded local park

EPA researchers are helping address runoff problems.

EPA researchers are developing strategies and resources to help city planners, managers, and others address stormwater runoff problems, including those related to impervious surfaces and combined sewer overflows. One powerful tool available is the Stormwater Management Model, also known by its acronym, “SWMM.”

EPA’s Storm Water Management Model is a publically-available rainfall-runoff simulation model that provides a suite of information about urban water patterns. It is used for planning, analysis, and design related to stormwater runoff, combined sewers, sanitary sewers, and other drainage systems in urban areas, and is the basis for the National Stormwater Calculator.

SWMM has the ability to estimate the pollution loads associated with stormwater runoff. Various versions of the model have been in existence since 1971, and it has been used in thousands of hydrology and drainage system design projects around the world.

The tool is designed to be customizable, helping particular urban areas meet local watershed challenges. For example, municipalities and communities can use it to design and size drainage system components for flood control, to design control strategies for minimizing combined sewer overflows, and to control site runoff using low impact development practices.

The Storm Water Management Model Climate Adjustment Tool (SWMM-CAT) is a new addition to SWMM. It is a simple to use software utility that allows future climate change projections to be incorporated into SWMM.

Screen shot of EPA's SWMM-CAT tool showing a map with stormwater data

Storm Water Management Model

SWMM-CAT provides a set of location-specific adjustments that derived from global climate change models run as part of the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project Phase 3 (CMIP3) archive. These are the same climate change simulations that helped inform the United Nations Intergovernmental Panel on Climate Change in preparing its Fourth Assessment report.

Both SWMM and the Stormwater Calculator are a part of the President’s Climate Action Plan.

“Climate change threatens our health, our economy, and our environment,” said Gina McCarthy, EPA Administrator. “As part of the President’s Climate Action Plan, this tool will help us better prepare for climate impacts by helping build safer, sustainable, and more resilient water infrastructure.”

The continued development of predictive modeling tools such as SWMM will provide urban planners and other stakeholders with the resources they need to incorporate both traditional stormwater and wastewater system technologies with the emerging, innovative techniques of green infrastructure. The collective impact will be more sustainable urban areas and healthier waterways across the nation.

SWMM-CAT can be downloaded here.

If you are interested in learning more about SWMM-CAT, join our webinar on 2/25/15 at 12:00 PM ET!

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

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