Georgia Water Science Center

USGS Water-Resources Investigations Report 95-4017

FLOOD-FREQUENCY RELATIONS FOR URBAN STREAMS IN GEORGIA—1994 UPDATE

This report is available online in pdf format (1 MB): USGS WRIR 95-4017 (Opens the PDF file in a new window. )

Ernest J. Inman

U.S. Geological Survey Water-Resources Investigations Report 95-4017, 27 pages (Published 1995)

ABSTRACT

A statewide study of flood magnitude and frequency in urban areas of Georgia was made to develop methods of estimating flood characteristics at ungaged urban sites. A knowledge of the magnitude and frequency of floods is needed for the design of highway drainage structures, establishing flood-insurance rates, and other uses by urban planners and engineers.

A U.S. Geological Survey rainfall-runoff model was calibrated for 65 urban drainage basins ranging in size from 0.04 to 19.1 square miles in 10 urban areas of Georgia. Rainfall-runoff data were collected for a period of 5 to 7 years at each station beginning in 1973 in Metropolitan Atlanta and ending in 1993 in Thomasville, Ga. Calibrated models were used to synthesize long-term annual flood peak discharges for these basins from existing long-term rainfall records. The 2- to 500-year flood-frequency estimates were developed for each basin by fitting a Pearson Type III frequency distribution curve to the logarithms of these annual peak discharges.

Multiple-regression analyses were used to define relations between the station flood-frequency data and several physical basin characteristics, of which drainage area and total impervious area were the most statistically significant. Using these regression equations and basin characteristics, the magnitude and frequency of floods at ungaged urban basins can be estimated throughout Georgia.


CONTENTS

Abstract

Introduction

Purpose and scope

Previous studies

Acknowledgments

Site selection

Data collection and processing

Current data

Long-term rainfall and daily pan-evaporation data

Flood-frequency relations

Description of rainfall-runoff model

Calibration

Verification

Flood-frequency analysis

Regional regression analysis

Regional flood-frequency estimating equations

Testing of regression equations

Bias

Sensitivity

Standard error of prediction

Use of flood-frequency relations

Summary

Selected references

 


REPORT AVAILABILITY

This report is available online in pdf format (1 MB): USGS WRIR 95-4017 (Opens the PDF file in a new window. )
To view the PDF document, you need the Adobe Acrobat® Reader installed on your computer. (a free copy of the Acrobat® Reader may be downloaded from Adobe Systems Incorporated.)


Recent USGS publications on Georgia or Georgia Water-Resources Information

For more information, please contact webmaster-ga@usgs.gov .

Accessibility FOIA Privacy Policies and Notices

Take Pride in America home page. FirstGov button U.S. Department of the Interior | U.S. Geological Survey
URL: https://pubs.usgs.gov/wri/wri95-4017/index.html
Page Contact Information: Publications Team
Page Last Modified: Wednesday, 07-Dec-2016 13:31:34 EST