Preliminary report on a study to estimate flood volumes of small rural streams in Ohio: Methods, site selection, and data base

Abstract

In 1981, the U.S. Geological Survey, in cooperation with the Ohio Department of Transportation and the Federal Highway Administration, began a 7-year flood-volume study of small rural basins in Ohio. This report summarizes the methods of study and describes reconnaissance and site-selection procedures, locations and characteristics of the stations, instrumentation, and methods of collecting and storing data. The first phase of this study involved an intensive field reconnaissance of about 7,000 sites, of which 32 basins were selected for detailed analysis. Drainage areas for the basins varied from 0.13 to 6.45 square miles, and main-channel slopes ranged from 7.6 to 276 feet per mile. Five years of 5-minute rainfall-runoff data will be colledted for each study site. These data will be used to calibrate and verify a rainfall-runoff model for each basin. The calibrated model will be used in conjunction with 80 years of National Weather Service 5-minute precipitation data to synthesize a representative 80-year streamflow record at each site. A Log-Pearson Type III frequency distribution will be applied to each record to define the magnitudes and frequencies of flood volumes at each site. These data will be used to develop regionalized multiple regression models for estimating flood-volume magnitudes and frequencies at small rural ungaged sites in Ohio. The report also summarizes rainfall-runoff data collected from July 1981 through September 1983, but does not interpret the data. An average of eleven event periods per site were monitored where maximum 5-minute rainfall intensities varied from 0.02 to .067 inches and maximum peak discharges varied from 1 to 1,130 cubic feet per second.