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Scientific Investigations Report 2010–5012

Prepared in cooperation with the Alabama Department of Transportation

Magnitude and Frequency of Floods for Urban Streams in Alabama, 2007

By T.S. Hedgecock and K.G. Lee

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Methods of estimating flood magnitudes for exceedance probabilities of 50, 20, 10, 4, 2, 1, 0.5, and 0.2 percent have been developed for urban streams in Alabama that are not significantly affected by dams, flood detention structures, hurricane storm surge, or substantial tidal fluctuations. Regression relations were developed using generalized least-squares regression techniques to estimate flood magnitude and frequency on ungaged streams as a function of the basin drainage area and percentage of basin developed. These methods are based on flood-frequency characteristics for 20 streamgaging stations in Alabama and 3 streamgaging stations in adjacent States having 10 or more years of record through September 2007.

First posted June 7, 2010

For additional information contact:
USGS Alabama Water Science Center
75 TechnaCenter Drive
Montgomery, AL 36117

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

Hedgecock, T.S., and Lee, K.G., 2010, Magnitude and frequency of floods for urban streams in Alabama, 2007: U.S. Geological Survey Scientific Investigations Report 2010–5012, 17 p.




Purpose and Scope

Previous Studies

Description of the Study Area

Flood Data Used in the Analysis

Flood Magnitude and Frequency at Gaging Stations

Urban Flood-Frequency Analysis

Accuracy and Limitations of Flood-Frequency Estimates

Use of Flood-Frequency Relations

Comparison of Results with Previous Alabama Study Results



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