Source: USEPA

http://www.washingtonnature.org

• Stormwater Management Model (SWMM)

• National Stormwater Calculator (SWC)

• Driven by the SWMM model, the SWC focuses primarily on the estimate of annual rainfall and above-ground stormwater runoff.

• User supplies information about site’s land cover, plus the potential application of low-impact development control practices to reduce stormwater runoff at the modeled site.

• For planning, analysis, and design related to stormwaterrunoff

• Local storm water system can be modeled explicitly and with great detail

• Simulates single or long-term scenarios

Sub-catchmentAreas

UndergroundStormwater

Conduits

Rain GaugeOutlet

• SWMM accounts for various hydrologic processes that produce runoff from urban areas:

Low impact development (LID) controls

• Free, though can be costly to truly utilize

• Example: City of Ann Arbor

• Hired a consulting firm to help with customization and implementation of the model

• Purchased equipment to monitor flow and calibrate the model

• Compared model output with measured flow

• Calibrated the modeling system

• Cost of project was on the order of $1-2 million!

• National Stormwater Calculator (NSC)