USGS


Techniques for Estimating Peak-Streamflow Frequency for Unregulated Streams and Streams Regulated by Small Floodwater Retarding Structures in Oklahoma

By Robert L. Tortorelli

 

Prepared in cooperation with the OKLAHOMA DEPARTMENT OF TRANSPORTATION

 

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 97–4202

 

This report is also available as a pdf.

 

 


ABSTRACTS

Statewide regression equations for Oklahoma were determined for estimating peak discharge and flood frequency for selected recurrence intervals from 2 to 500 years for ungaged sites on natural unregulated streams. The most significant independent variables required to estimate peak-streamflow frequency for natural unregulated streams in Oklahoma are contributing drainage area, main-channel slope, and mean-annual precipitation. The regression equations are applicable for watersheds with drainage areas less than 2,510 square miles that are not affected by regulation from manmade works.

Limitations on the use of the regression relations and the reliability of regression estimates for natural unregulated streams are discussed. Log-Pearson Type III analysis information, basin and climatic characteristics, and the peak-stream-flow frequency estimates for 251 gaging stations in Oklahoma and adjacent states are listed.

Techniques are presented to make a peak-streamflow frequency estimate for gaged sites on natural unregulated streams and to use this result to estimate a nearby ungaged site on the same stream. For ungaged sites on urban streams, an adjustment of the statewide regression equations for natural unregulated streams can be used to estimate peak-streamflow frequency. For ungaged sites on streams regulated by small floodwater retarding structures, an adjustment of the statewide regression equations for natural unregulated streams can be used to estimate peak-streamflow frequency. The statewide regression equations are adjusted by substituting the drainage area below the floodwater retarding structures, or drainage area that represents the percentage of the unregulated basin, in the contributing drainage area parameter to obtain peak-streamflow frequency estimates.

CONTENTS

Abstract

Introduction

Purpose and scope

General description and effects of floodwater retarding structures

Acknowledgments

Estimation of peak-streamflow frequency for gaged sites on natural unregulated streams

Annual peak data

Historical peak streamflows

Low-outlier thresholds

Skew coefficients

Regression equations for estimation of peak-streamflow frequency for ungaged sites on natural unregulated streams

Regression analysis

Selected basin and climatic characteristics

Models investigated

Regression equations

Assumptions and applicability of regression equations

Accuracy and limitations

Application of techniques

Weighted peak-streamflow frequency estimates for gaged sites on natural unregulated streams unregulated streams

Peak-streamflow frequency estimates for ungaged sites near gaged sites on natural unregulated streams unregulated streams

Adjustment for ungaged sites on urban streams

Adjustment for ungaged sites on streams regulated by floodwater retarding structures

Examples of techniques

Weighted peak-streamflow frequency estimates for gaged sites on natural unregulated streams

Peak-streamflow frequency estimates for ungaged sites near gaged sites on natural unregulated streams

Adjustment for ungaged sites on urban streams

Adjustment for ungaged sites on streams regulated by floodwater retarding structures

Summary

Selected references


For more information:

 

District Chief

U.S. Geological Survey

202 NW 66 St., Bldg 7

Oklahoma City, OK 73116

 

For sale by:

 

U.S. Geological Survey

Information Center

Box 25286, MS 517

Denver Federal Center

Denver, CO 80225

 

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Telephone: 1-888-ASK-USGS

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Information about water resources in Oklahoma is available on the World Wide Web at:

http://ok.water.usgs.gov

 


U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/wri974202
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Last modified: Thursday, September 01 2005, 02:04:10 PM
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