Development of Regional Curves Relating Bankfull-Channel Geometry and Discharge to Drainage Area for the Rocky Mountain Hydrologic Region in Wyoming

Regional curves are statistical models (one-variable, ordinary least-squares regressions) that relate bankfull discharge, bankfull cross-sectional area, bankfull width, and bankfull mean depth of streams to drainage area in settings that are expected to have similar runoff characteristics. Equations describing the regional curves can be used to estimate the discharge and dimensions of the bankfull channel when the drainage area of the watershed is known. These equations are useful for identifying the bankfull channel in areas with similar runoff characteristics. Regional curves also are used to determine channel departure from reference conditions and to plan stream restoration when using Natural Channel Design techniques (Rosgen, 2006).

Numerous state agencies, including the WDEQ, WGFD, and Wyoming Department of Transportation have expressed the need for regional curves related to bankfull flows for a number of applications, such as structure (for example, water diversions) design and placement, streamflow regulation, habitat monitoring and assessment, and designing restoration or habitat enhancement projects. In FY2010, the WDEQ funded development of regional curves for a few selected watersheds in Wyoming. Although some work already had been completed in the upper Green River watershed (Leopold, 1994; Rosgen, 2006), there are watersheds in the Atlantic Rim area and the majority of the Green River basin for which regional curves had not been developed and where they are needed in the face of imminent energy development (Foster, 2012). The WDEQ, WGFD, and WLCI funded this work to develop curves in the Rocky Mountains Hydrologic Region, which includes the WLCI study area. The BLM, WGFD, and Trout Unlimited have implemented stream assessments that benefited from this work. In FY2012, this project was completed with publication of a final report (Foster, 2012).

Foster, K., 2012, Bankfull-channel geometry and discharge curves for the Rocky Mountains Hydrologic Region in Wyoming: U.S. Geological Survey Scientific Investigations Report 2012-5178, 20 p., at http://pubs.usgs.gov/sir/2012/5178/sir2012-5178.pdf.
Leopold, L.B., 1994, A view of the river: Cambridge, Mass., Harvard University Press, 298 p.
Rosgen, D.L., 2006, Watershed assessment of river stability and sediment supply (WARSSS): Fort Collins, Colo., Wildland Hydrology, 193 p.

 
Products Completed in FY2012

• Foster, K., 2012, Bankfull-channel geometry and discharge curves for the Rocky Mountains Hydrologic Region in Wyoming: U.S. Geological Survey Scientific Investigations Report 2012-5178, 20 p., at http://pubs.usgs.gov/sir/2012/5178/sir2012-5178.pdf.

• Preliminary regional curves for 40 sites located throughout Wyoming (6 of which are in the WLCI area)
• Foster, K., DRAFT: Development of regional curves relating bankfull-channel geometry and discharge to drainage area for the Rocky Mountain Hydrologic Region in Wyoming: A report to the Sublette County Conservation District, Wyoming. 

• Regional curve dataset.
• Preliminary regional curves.
• Foster, K., in review, development of regional curves relating bankfull-channel geometry and discharge to drainage area for the Rocky Mountain Hydrologic Region in Wyoming: U.S. Geological Survey Scientific Investigations Report.