DETERMINING STREAM CHANNEL DEGRADATION AND THE POTENTIAL NEED FOR STREAM REHABILITATION IN URBANIZING WATERSHEDS
Location: Grassland, Soil and Water Research Laboratory
Project Number: 6206-13610-007-16
Start Date: Mar 13, 2012
End Date: Mar 31, 2013
Determine the rates of potential stream channel widening and down cutting in watersheds that are impacted by increasing urbanization. U.S. EPA Stormwater Policy requires the nation's streams be assessed based on impacts of urbanization on water quality and channel degradation.
Numerous studies exist across the U.S. that relate river and watershed relationship characteristics such as drainage area, two-year flow, slope, and D50 to channel width and depth. Regional relationships have been developed, but there are currently no national relationships or a comprehensive national set of relationships. In this study, we will assemble all existing channel studies into a database, examine existing regional relationships, and develop a national set of equations relating channel width and depth to watershed characteristics. USGS regression equations are currently available by State that relate bank-full flow to watershed land use, including urbanization. U.S. EPA estimates of increasing urbanization will be used in the USGS equation for flow impact, which will then be used in the equations that relate flow to channel width and depth. Thus, urbanization impacts on channel widening and down cutting will be estimated, and miles of streams in the U.S. requiring rehabilitation will be determined.