North Carolina Flood Frequency Statistics

Flood-Frequency Statistics
USGS Gaged Sites

OBTAIN FLOOD-FREQUENCY STATISTICS:
To locate a particular site through a series of interactive maps, click on one of the major headings below.
River Basin Map County Map Streamgage Map
Or, if you know which river basin, county, or streamgage you are interested in, select one from the list.




Reliable estimates of the magnitude and frequency of floods are needed for numerous design and management functions throughout North Carolina. For U.S. Geological Survey (USGS) streamgage sites where more than 10 years of annual peak-flow data have been recorded, estimates of flood frequency can be computed using statistical analysis. This Web page was developed in cooperation with the North Carolina Department of Transportation (NCDOT) for users to obtain site information and flood-frequency estimates for specific stream sites.

Using peak-flow data compiled through 1996, computed flood-frequency estimates are presented for gaged sites with more than 10 years of annual peak-flow record. Log-Pearson Type III estimates are presented for the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year flood discharges for both regulated and unregulated sites. For some sites, differing flood-frequency estimates are presented for periods of both regulated and unregulated flow conditions. Flood-frequency estimates at unregulated sites can be improved by weighting the log-Pearson Type III estimate using regional methods as described in Bulletin 17B (Hydrology Subcommittee of the Interagency Advisory Committee on Water Data, 1981). Weighted estimates at unregulated sites also are presented. Further details regarding computational methods can be found in Pope and others, 2001.

References

Hydrology Subcommittee of the Interagency Advisory Committee on Water Data, 1981, Guidelines for determining flood frequency: Reston, VA., U.S. Geological Survey Bulletin 17B, Office of Water Data Collection, 183 p. (corrected editorially in March 1982).

Pope, B.F., Tasker, G. D., and Robbins, J.C., 2001, Estimating the magnitude and frequency of floods in rural basins of North Carolina - Revised: U.S. Geological Survey Water-Resources Investigations Report 01-4207, 42 p. + app.

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Page Last Modified: Tuesday, October 2 2007, 02:01:39 PM