Magnitude and frequency of floods in Alaska south of the Yukon River

Circular 493
Prepared in cooperation with the Alaska State Highway Department and the U.S. Bureau of Public Roads
By: , and 



This report presents a method for evaluating the magnitude and frequency of floods on the basis of the analysis of flood records. One composite frequency curve is applied to the entire study region. This curve relates floods of various magnitudes at any site within the region to probable recurrence intervals (from 1.1 to 50 years) for those floods. Flood magnitudes are reduced to dimensionless form by expressing them as a ratio to mean annual flood. Magnitudes of mean annual floods vary with the flood-producing characteristics of stream basins. On the basis of the limited data available, drainage-area size is found to be the only significant factor affecting the magnitude of the mean annual flood. Trial and error groupings of gaging-station records show that the region can be split into three hydrologic areas: one curve defines the relation within each area between mean annual flood and drainage area. These three curves in combination with the composite flood-frequency curve permit, for natural-flow conditions at any site, the determination of flood magnitude for a given recurrence interval, or the determination of recurrence interval for a flood of known magnitude.

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Magnitude and frequency of floods in Alaska south of the Yukon River
Series title Circular
Series number 493
DOI 10.3133/cir493
Year Published 1964
Language ENGLISH
Publisher U.S. Geological Survey
Description Report: iii, 15 p.; 1 Map: 19.27 x 16.80 inches
Country United States
State Alaska
Other Geospatial Yukon River
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