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 equations/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
NEW USFWS Hydraulic Geometry Relationships in the Maryland Piedmont and Mountains
Piedmont - Urban