EPA stormwater calculator estimates rainwater runoff

The United States Environmental Protection Agency (EPA) has developed a National Stormwater Calculator that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the country.

The desktop application uses estimates that are based on local soil conditions, land cover, and historic rainfall records.

The calculator accesses several national databases that provide soil, topography, rainfall, and evaporation information for the chosen site. Simply supply information about your site’s land cover and select the types of low impact development controls you would like to use.  They include such green infrastructure practices as disconnection, rain harvesting, rain gardens, green roofs, street planters, infiltration basins and porous pavement.

Green infrastructure promotes the natural movement of water, instead of allowing it to wash into streets and down storm drains, the EPA says. The calculator is designed to help protect and restore the environmental integrity of the nation’s waterways.