USGS

The National Flood Frequency Program, Version 3:

A Computer Program for Estimating Magnitude and Frequency of Floods for Ungaged Sites

Water-Resources Investigations Report 02-4168

Compiled by K.G. Ries III and M.Y. Crouse

This report is available as a pdf.

Abstract

For many years, the U.S. Geological Survey (USGS) has been developing regional regression equations for estimating flood magnitude and frequency at ungaged sites. These regression equations are used to transfer flood characteristics from gaged to ungaged sites through the use of watershed and climatic characteristics as explanatory or predictor variables. Generally, these equations have been developed on a Statewide or metropolitan-area basis as part of cooperative study programs with specific State Departments of Transportation.

In 1994, the USGS released a computer program titled the National Flood Frequency Program (NFF), which compiled all the USGS available regression equations for estimating the magnitude and frequency of floods in the United States and Puerto Rico. NFF was developed in cooperation with the Federal Highway Administration and the Federal Emergency Management Agency. Since the initial release of NFF, the USGS has produced new equations for many areas of the Nation. A new version of NFF has been developed that incorporates these new equations and provides additional functionality and ease of use.

NFF version 3 provides regression-equation estimates of flood-peak discharges for unregulated rural and urban watersheds, flood-frequency plots, and plots of typical flood hydrographs for selected recurrence intervals. The Program also provides weighting techniques to improve estimates of flood-peak discharges for gaging stations and ungaged sites. The information provided by NFF should be useful to engineers and hydrologists for planning and design applications.

This report describes the flood-regionalization techniques used in NFF and provides guidance on the applicability and limitations of the techniques. The NFF software and the documentation for the regression equations included in NFF are available at http://water.usgs.gov/software/nff.html.

Contents


Abstract

 

INTRODUCTION
— By W.O. Thomas, Jr., M.E. Jennings, and K.G. Ries III

 

Purpose

Report Format

How to Obtain the NFF Software and Documentation

Acknowledgments

 

HISTORY AND OVERVIEW OF FLOOD REGIONALIZATION METHODS
— By W.O. Thomas, Jr., and K.G. Ries III

 

INTRODUCTION

INDEX-FLOOD PROCEDURES

ORDINARY-LEAST-SQUARES REGRESSION

WEIGHTED- AND GENERALIZED-LEAST-SQUARES REGRESSION

REGION-OF-INFLUENCE REGRESSION

RURAL FLOOD-FREQUENCY ESTIMATING TECHNIQUES
— By K.G. Ries III, W.O. Thomas, Jr., and J.B. Atkins

 

INTRODUCTION

WATERSHED AND CLIMATIC CHARACTERISTICS

HYDROLOGIC FLOOD REGIONS

MEASURES OF ACCURACY

TECHNIQUES FOR WATERSHEDS THAT SPAN REGIONAL/STATE BOUNDARIES

WEIGHTING OF INDEPENDENT ESTIMATES OF RURAL FLOOD FREQUENCY

Weighting for Streamgaging Stations

Weighting for Ungaged Sites

 

URBAN FLOOD-FREQUENCY ESTIMATING TECHNIQUES
— By V.B. Sauer

 

INTRODUCTION

NATIONWIDE URBAN EQUATIONS

LOCAL URBAN EQUATIONS

 

FLOOD HYDROGRAPH ESTIMATION
— By V.B. Sauer

 

ESTIMATION OF EXTREME FLOODS
— By W.O. Thomas, Jr. and W.H. Kirby

 

MEASURES OF EXTREME FLOODS

EXTRAPOLATION FOR THE 500-YEAR FLOOD

 

TESTING AND VALIDATION OF TECHNIQUES
— By K.G. Ries III

 

APPLICABILITY AND LIMITATIONS
— By J.B. Atkins and K.G. Ries III

 

SUMMARY OF STATE FLOOD-FREQUENCY TECHNIQUES
— By K.G. Ries III, H.C. Riggs, and W.O. Thomas, Jr

 

REFERENCES

APPENDIX A—

 

NATIONAL FLOOD FREQUENCY PROGRAM USERS' MANUAL
— by R. Dusenbury, M. Gray, and K.G. Ries III

 

DOWNLOADING AND INSTALLING THE PROGRAM

STARTING THE PROGRAM

MAIN WINDOW

Menu Items

File menu

Graph menu

Help menu

Manual

Web site

About

EDIT SCENARIO WINDOW

FREQUENCY WINDOW

HYDROGRAPH WINDOW

WEIGHT WINDOW


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