Techniques for Estimating Flood-Peak Discharges of Rural, Unregulated Streams in Ohio

Water-Resources Investigations Report 2003-4164
Prepared in cooperation with the Ohio Department of Transportation, and the U.S. Department of Transportation, Federal Highway Administration


  • Document: Report (2.76 MB pdf)
  • Metadata:
    • Metadata - Ohio-Drainage Digital Elevation Model for use with Water Resources Investigations Report 03-4164
    • Metadata - Ohio fFood Regions for use with Water Resources Investigations Report 03-4164
  • Download citation as: RIS | Dublin Core


Regional equations for estimating 2-, 5-, 10-, 25-, 50-, 100-, and 500-year flood-peak discharges at ungaged sites on rural, unregulated streams in Ohio were developed by means of ordinary and generalized least-squares (GLS) regression techniques. One-variable, simple equations and three-variable, full-model equations were developed on the basis of selected basin characteristics and flood-frequency estimates determined for 305 streamflow-gaging stations in Ohio and adjacent states. The average standard errors of prediction ranged from about 39 to 49 percent for the simple equations, and from about 34 to 41 percent for the full-model equations. Flood-frequency estimates determined by means of log-Pearson Type III analyses are reported along with weighted flood-frequency estimates, computed as a function of the log-Pearson Type III estimates and the regression estimates.

Values of explanatory variables used in the regression models were determined from digital spatial data sets by means of a geographic information system (GIS), with the exception of drainage area, which was determined by digitizing the area within basin boundaries manually delineated on topographic maps. Use of GIS-based explanatory variables represents a major departure in methodology from that described in previous reports on estimating flood-frequency characteristics of Ohio streams.

Examples are presented illustrating application of the regression equations to ungaged sites on ungaged and gaged streams. A method is provided to adjust regression estimates for ungaged sites by use of weighted and regression estimates for a gaged site on the same stream.

A region-of-influence method, which employs a computer program to estimate flood-frequency characteristics for ungaged sites based on data from gaged sites with similar characteristics, was also tested and compared to the GLS full-model equations. For all recurrence intervals, the GLS full-model equations had superior prediction accuracy relative to the simple equations and therefore are recommended for use.

Suggested Citation

Koltun, G.F., 2003, Techniques for estimating flood-peak discharges of rural, unregulated streams in Ohio: U.S. Geological Survey Water-Resources Investigations Report 2003–4164, 75 p.,

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Techniques for Estimating Flood-Peak Discharges
  • Data Compilation
  • Development of Flood-Frequency Estimates for Streamflow-Gaging Stations
  • Development of Regional Regression Equations
  • Region of Influence
  • Summary and Conclusions
  • References Cited
  • Data Tables
  • Appendixes
Publication type Report
Publication Subtype USGS Numbered Series
Title Techniques for estimating flood-peak discharges of rural, unregulated streams in Ohio
Series title Water-Resources Investigations Report
Series number 2003-4164
DOI 10.3133/wri034164
Edition 2nd edition
Year Published 2003
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Description vi, 75 p.; Metadata
Country United States
State Ohio
Google Analytic Metrics Metrics page
Additional publication details