USGS

EFFECTS OF URBANIZATION ON THE MAGNITUDE AND FREQUENCY OF FLOODS ON SMALL STREAMS IN TENNESSEE - BASIC DATA REPORT NO. 2

U.S. Geological Survey, Open-File Report 82-911

by Clarence H. Robbins

This report is available as a pdf below


Preface

Engineers involved in bridge, culvert and highway design often find it necessary to know the magnitude and frequency of discharge from small streams where the drainage basin is urbanized. In order to develop an adequate method for determining the frequency of floods on small streams in Tennessee, where urbanization is a factor, a considerable amount of runoff data are needed. At present there is a scarcity of runoff data from urban areas in Tennessee except in large metropolitan areas. With this in mind the U.S. Geological Survey and the Tennessee Department of Transportation entered into a cooperative agreement in July 1977 to collect data on streams draining less than about 25 mi2 in municipalities with populations ranging between 5,000 and 100,000. The data collected under this project, in combination with urban runoff data collected in Memphis, Nashville and Knoxville, will give a full spectrum of runoff conditions likely to be experienced in Tennessee.

A total of 22 sites have been instrumented across the State as shown in figure 1. Each of the four hydrologic areas as defined in the report "Technique for Estimating Magnitude and Frequency of Floods in Tennessee," 1976, by Randolph and Gamble is represented.

This report summarizes data collected at these 22 sites during the period July 1977, to June 1982, and is the second basic data report to be released during the term of this project. The data presented in this report supersedes data in Basic Data Report No. 1.

After sufficient data have been collected and analyzed, the Geological Survey Rainfall-Runoff model will be calibrated using these data. Urban runoff data from similar studies in Memphis, Nashville, and Knoxville will be incorporated into the data base of this study for the flood frequency analysis. Regional flood-frequency equations for the 2-year through the loo-year recurrence interval floods for small streams in urbanized areas will be developed using the expanded data base.

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