U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 03-4188
Estimating the Magnitude and Frequency of Peak Streamflows for Ungaged Sites on Streams in Alaska and Conterminous Basins in Canada
Prepared in cooperation with
ALASKA DEPARTMENT OF TRANSPORTATION
AND PUBLIC FACILITIES
By Janet H. Curran, David F. Meyer, and Gary D. Tasker
Estimates of the magnitude and frequency of peak streamflow are needed across Alaska for floodplain management, cost-effective design of floodway structures such as bridges and culverts, and other water-resource management issues. Peak-streamflow magnitudes for the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence-interval flows were computed for 301 streamflow-gaging and partial-record stations in Alaska and 60 stations in conterminous basins of Canada. Flows were analyzed from data through the 1999 water year using a log-Pearson Type III analysis. The State was divided into seven hydrologically distinct streamflow analysis regions for this analysis, in conjunction with a concurrent study of low and high flows. New generalized skew coefficients were developed for each region using station skew coefficients for stations with at least 25 years of systematic peak-streamflow data.
Equations for estimating peak streamflows at ungaged locations were developed for Alaska and conterminous basins in Canada using a generalized least-squares regression model. A set of predictive equations for estimating the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year peak streamflows was developed for each streamflow analysis region from peak-streamflow magnitudes and physical and climatic basin characteristics. These equations may be used for unregulated streams without flow diversions, dams, periodically releasing glacial impoundments, or other streamflow conditions not correlated to basin characteristics. Basin characteristics should be obtained using methods similar to those used in this report to preserve the statistical integrity of the equations.
Description of Study Area
Determination of Drainage-Basin Characteristics
Determination of Streamflow Analysis Regions
Estimating Peak Streamflows at Gaged Sites
Regional Equations for Estimating Peak Streamflows
Procedures for Estimating Peak Streamflow Magnitude and Frequency
Appendix A. Years of Record for Annual Peak Streamflows Used in This Report
Appendix B. Accuracy of Estimating Equations
This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Download the report (PDF, 5.7 MB)
Select Plate 1 (PDF, 3.84 MB) to view or print.
Other downloadable items:
Tools for Estimating Streamflow
Computer program to compute peak-streamflow frequencies, standard error of prediction, confidence limits, and equivalent years of record for ungaged sites (ZIP file, 138 KB). After downloading, unzip using WINZIP (evaluation version available free at www.winzip.com). Run the program by double-clicking reg.exe. The program expects the file split.cmn to be in the same folder as reg.exe. View the FORTRAN code by opening reg.for.
Regression equations for estimating 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year peak streamflows for unregulated streams in Regions 1-7, Alaska and conterminous basins in Canada (table 3, 28 KB)
Data for Figure 2, Relation of discharge to drainage area for selected recurrence intervals for the Yukon River, Alaska and Canada. (15 KB)
Generalized skew and summary statistics for Regions 1-7, Alaska and conterminous basins in Canada (table 2, 15 KB)
Station information and peak-streamflow statistics for streamflow-gaging and partial-record stations in Alaska and conterminous basins in Canada (table 4, 299 KB)
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For additional information contact:
Alaska Science Center, Water Resources Office
U.S. Geological Survey
4230 University Drive, Suite 201
Anchorage, AK 99508-4664
Please visit http://alaska.usgs.gov/ for more information about USGS activities in Alaska.
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