USGS Updates Methods for Computing Flood Flows in Wyoming

Even though much of Wyoming is in the grip of a multi-year drought, rain and snow will fall again, rivers will flow and floods will occur. The U.S. Geological Survey (USGS) in cooperation with the Wyoming Department of Transportation, recently updated methods for calculating peak flows for streams in the State.

"Engineers, planners, and scientists often need peak flow information for streams where no streamflow data exist," said study leader Kirk Miller, a USGS hydrologist.

While data collected at a stream or river provides the best information, collection of these data requires time and money.

"With these methods, peak flows can be computed for sites without streamflow data. Using a calculator and the local physical or climatic characteristics, such as elevation and rainfall, you can compute the estimated peak flow for a flood on most any stream in Wyoming," said Miller.

The USGS has been refining methods for computing peak flows in Wyoming since 1963. This most recent study is an update of methods derived in 1988.

"The study resulted in equations with less uncertainty for most of the State," Miller added, "as well as better accuracy in some parts."

The study resulted in statistically-derived equations for estimating peak flows on unregulated streams for six hydrologic regions of the State. The regional equations require different combinations of up to three basin characteristics--including drainage area, elevation, precipitation, soil properties, and geographic location--for calculating peak flows for the 1.5- up to the 500-year flood.

Copies of the report "Peak-Flow Characteristics of Wyoming Streams" are available by contacting the USGS office in Cheyenne at 307/778-2931 or online at http://pubs.water.usgs.gov/wri034107/.

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