- Ground Water
ABOUT THE ILLINOIS
Water Science Center
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USGS Water Science Centers are located in each state.
In cooperation with the Illinois Center for Transportation, Illinois Department of Transportation, and the Illinois Department of Natural Resources—Office of Water Resources
Estimating Flood-Peak Magnitudes and Frequencies for Rural Streams in Illinois
By David T. Soong, Audrey L. Ishii, Jennifer B. Sharpe, and Charles F. Avery
Flood-peak discharge magnitudes and frequencies at streamflow-gaging sites were developed with the annual maximum series (AMS) and the partial duration series (PDS) in this study. Regional equations for both flood series were developed for estimating flood-peak discharge magnitudes at specified recurrence intervals of rural Illinois streams. The regional equations are techniques for estimating flood quantiles at ungaged sites or for improving estimated flood quantiles at gaged sites with short records or unrepresentative data. Besides updating at-site flood-frequency estimates using flood data up to water year 1999, this study updated the generalized skew coefficients for Illinois to be used with the Log-Pearson III probability distribution for analyzing the AMS, developed a program for analyzin the partial duration series with the Generalized Pareto probability distribution, and applied the BASINSOFT program with digital datasets in soil, topography, land cover, and precipitation to develop a set of basin characteristics. The multiple regression analysis was used to develop the regional equations with subsets of the basin characteristics and the updated at-site flood frequencies. Seven hydrologic regions were delineated using physiographic and hydrologic characteristics of drainage basin of Illinois. The seven hydrologic regions were used for both the AMS and PDS analyses.
Examples are presented to illustrate the use of the AMS regional equations to estimate flood quantiles at an ungaged site and to improve flood-quantile estimates at and near a gaged site. Flood-quantile estimates in four regulated channel reaches of Illinois also are approximated by linear interpolation. Documentation of the flood data preparation and evaluation, procedures for determining the flood quantiles, basin characteristics, generalized skew coefficients, hydrologic region delineations, and the multiple regression analyses used to determine the regional equations are presented in the main text and appendixes.
First posted November 2004
For additional information contact:
Director, Illinois Water Science Center
U.S. Geological Survey
405 North Goodwin Drive
Urbana, IL 61801
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August 10, 2010:
- Equation 13 on page 26 was corrected. Please see the Errata on page viii of the report for more information.
January 14, 2015:
- Revisions were made to the Errata of August 10, 2010 and June 28, 2012. Please see page viii of the report for the full description.
Soong, D.T., Ishii, A.L., Sharpe, J.B., and Avery, C.F., 2004, Estimating Flood-Peak Discharge Magnitudes and Frequencies for Rural Streams in Illinois: U.S. Geological Survey Scientific Investigations Report 2004–5103, 147 p.
Flood-Peak Discharge Magnitudes and Frequencies at Gaged Sites
Regional Frequency Analysis
Techniques for Estimating Flood-Peak Discharge Magnitudes and Frequencies
Summary and Conclusions