Technical Resources
Regional Curves
Bankfull hydraulic geometry relationships, also called regional curves, were first developed by Dunne and Leopold (1978), and relate bankfull channel dimensions to drainage area. Gage station analyses throughout the United States have shown that bankfull discharge has an average return interval of about 1.5 years or 67% annual exceedence probability. The primary purpose for developing regional curves is to aid in identifying bankfull stage and dimension in an un-gaged watershed and to help estimate the bankfull dimension and discharge for natural channel designs.
Note: These are draft relationships. The relationships/curves are sufficient for identifying bankfull stage in ungaged watersheds. However, caution should be used in applying them to natural channel designs until the final relationships have been peer reviewed and published.
See River Course Fact Sheet #3 for more detailed infomation of Identifying Bankfull in North Carolina streams.
US Forest Service Video on Identifying Bankfull in forested Eastern US streams.
USFWS Hydraulic Geometry Relationships in the Maryland Piedmont and Mountains
Regional Curves for the Three Physiographic Regions of North Carolina
Coastal
- - Graphs, Equations and Data
- - Papers/Presentations: Doll, Barbara A., A.D. Dobbins, J. Spooner, D.R. Clinton and D.A. Bidelspach, 2003, Hydraulic Geometry Relationships for Rural North Carolina Coastal Plain Streams, NC Stream Restoration Institute, Report to N.C. Division of Water Quality for 319 Grant Project No. EW20011, www.ncsu.edu/sri. 11 pp.
Piedmont - Rural
- - Regional Curves/Graphs
- - Tables and Equations
- - Papers/Presentations: Harman, W.H. et al. 1999. Bankfull Hydraulic Geometry Relationships for North Carolina Streams. AWRA Wildland Hydrology Symposium Proceedings. Edited By: D.S. Olsen and J.P. Potyondy. AWRA Summer Symposium. Bozeman, MT.
Mountain - Rural
- - Regional Curves/Graphs
- - Tables and Equations
- - Papers/Presentations: Harman, W.H. et al. 2000. Bankfull Regional Curves for North Carolina Mountain Streams. In: Kane, D.L. (Ed.). Proc. AWRA Conf. Water Resources in Extreme Environments, Anchorage, AK. Pp. 185-190.
Piedmont - Urban
- - Regional Curve Graph and Equations
- - Data Table
- - Paper/Presentations: Doll, B.A. et al. 2002. Hydraulic Geometry Relationships for Urban Streams Throughout the Piedmont of North Carolina. J. American Water Resources Association. Vol.38, No.3. Pp. 641-651.
