EPA’s New Stormwater Calculator, Updated for Climate Change

ASLA 2011 Analysis and Planning Honor Award. GreenPlan Philadelphia / Wallace, Roberts & Todd (WRT)

The Environmental Protection Agency (EPA) recently updated its national stormwater calculator, which estimates the amount of rainwater and runoff from any site in the U.S., to reflect best estimates on future climate change. The EPA writes: “the calculator now includes changes in seasonal precipitation levels, the effects of more frequent high-intensity storms, and changes in evaporation rates based on validated Intergovernmental Panel on Climate Change (IPCC) climate change scenarios.” The first iteration of the calculator just covered soils conditions, slope, land cover, and historical rainfall records.

The goal is help developers, planners, and landscape architects understand how to best adapt our water management systems for a changing future. The new EPA administrator, Gina McCarthy, said: “climate change threatens our health, our economy, and our environment. 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 calculator software, which can be downloaded for free, enables users to discover how green infrastructure can reduce stormwater runoff. According to the EPA, the calculator first accesses several databases that offer soil, topography, rainfall, and evaporation information for any given site. Users then plug-in info about a site’s land cover and finally determines which types of green infrastructure they would like to use. Options include rain harvesting; rain gardens; green roofs; street planters; infiltration basins, or porous pavement.

The EPA says it’s best to develop a range of results using different assumptions about “percent of impervious surface, soil type, sizing of green infrastructure, as well as historical weather and future climate change scenarios” in order to comprehensive.

Download the new calculator.

In other green infrastructure news: The EPA announced five universities have received a $1 million grant to study urban green infrastructure practices in Philadelphia. These include Swarthmore College, Temple University, University of New Hampshire, University of Pennsylvania, and Villanova University. Researchers from these universities will collaborate closely with the Philadelphia Water Department.

Bob Perciasepe, EPA deputy administrator, said: “this pilot project with Philadelphia’s Green City, Clean Waters program will help us yield results and gain knowledge to help apply these practices in cities from coast to coast. And, these results can be increasing green spaces, creating jobs, saving energy and reducing urban heat island effects that contribute to climate change.”

Explore the EPA’s green infrastructure initiatives as well as ASLA’s resources.

2 thoughts on “EPA’s New Stormwater Calculator, Updated for Climate Change

  1. Landscape Architecture Foundation 03/07/2014 / 10:29 am

    Adding the climate change scenarios is a great step toward having our models be more accurate predictors of long-term performance. We’re excited to try the new version!

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