Learn how green infrastructure reduces flooding and improves water quality

Learn about what green infrastructure is and how it is included in flood projections.



Green infrastructure describes a group of adaptation measures included in the First Street Foundation Flood Model. Green infrastructure refers to man-made stormwater management infrastructure that relies on natural components such as plants, well-drained soils, and other “soft” materials to soak up runoff, thereby reducing flooding and improving surface water quality. The Federal Clean Water Act broadly defines green infrastructure as “...the range of measures that use plant or soil systems, permeable pavement or other permeable surfaces or substrates, stormwater harvest and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater and reduce flows to sewer systems or to surface waters."


NYC DEP green infrastructure rain garden rendering


Examples of green infrastructure projects include rain gardens, bioswales, and porous pavements. Green infrastructure projects, such as the rain gardens installed along Military Road in Auburn, WA (shown below), reduce frequent nuisance flooding from stormwater on nearby properties by soaking up excess runoff. Thousands of rain gardens and other green infrastructure projects were included in the First Street Foundation Flood Model. 


Left to right: rain garden, bioswale, porous pavement


Screen_Shot_2020-06-11_at_9.38.38_AM.pngRain gardens, a type of green infrastructure, in King County, WA that were included in the First Street Foundation’s Flood Model.


Naturally occurring environmental features such as wetlands and open space preserves are not considered green infrastructure. These features are not man-made projects constructed explicitly to reduce flooding. However, natural infrastructure like wetlands and open space preserves can also reduce flood risk, especially if policy is implemented to preserve these environmentally beneficial features.

coastal-wetlands_Mass_8070749192_a3ff208da1_k-1024x685.jpgCoastal saltmarsh as natural infrastructure, not man-made green infrastructure (photo courtesy of by Kelly Fike/U.S. Fish and Wildlife Service)


Flood risk reduction

Information on Flood Factor comes from the First Street Foundation Flood Model. Green infrastructure defines several of the 40 different types of flood risk reduction projects, known as adaptation, that this model considers when calculating and validating flood projections. 


The Adaptation Team continues to collect information on the flood infrastructure that exists across the country to make sure the Flood Model includes as many adaptation projects as possible. If you know of any projects that are not shown today, please help the team by submitting this flood protection project user input form. The adaptation database contains 23,000 features today. We know there are more projects to include and value your input!


Learn more

Historic flood methodology

Understand how stormwater management plans reduce rainwater runoff

How can community science and local knowledge improve the Flood Model?


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