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Frequency analysis of Illinois floods using observed and synthetic streamflow records

Water-Resources Investigations Report 77-104

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Abstract

Equations, applicable Statewide, for estimating flood magnitudes having recurrence intervals ranging from 2 to 500 years for unregulated rural streams, with drainage areas ranging from 0.02 to 10,000 square miles, were derived by multiple regression analyses. A rainfall-runoff model was used in the synthesis of long-term annual peak data for each of 54 small watersheds (drainage areas less than 10.2 sq mi). Synthetic frequency curves generated from five long-term precipitation stations were combined into one synthetic curve. This synthetic curve was combined with the observed station frequency curve to define the station frequency curve. Synthetic data from the 54 small streams, observed data at 33 small streams, and observed data at 154 large streams were used in the analyses. The most significant independent variables in the regression analysis for estimating flood peaks on Illinos stream were drainage area, slope, rainfall intensity, and an areal factor. (Woodard-USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Frequency analysis of Illinois floods using observed and synthetic streamflow records
Series title:
Water-Resources Investigations Report
Series number:
77-104
Edition:
-
Year Published:
1977
Language:
ENGLISH
Publisher:
U.S. Geological Survey, Water Resources Division,
Description:
v, 32 p. :ill., maps ;27 cm.