Basin descriptions were prepared to integrate information about basin characteristics and identify factors affecting regimen of flow of Ohio streams. Characteristics of flow at stream gaging stations were studied and interpreted in relation to specific basin characteristics. Ohio weather and climate, physiology, geology, soils, and development are described generally to provide geographic context.
Descriptions of all drainage basins in Ohio and basin maps showing outlines of basins and location of streams are provided. Selected streamflow characteristics useful for characterizing regimen of flow at gaging stations are tabulated for 250 stream gaging stations. The selected flow characteristics include: mean annual runoff, mean base-flow index, flow equaled or exceeded 10, 50, and 90 percent of the time, average 7-day, 2-year low flow, and 2-year recurrence interval flood-peak discharge.
Regulation from water development and hydro-modifications associated with land development affects flows to varying degree at many stream gaging stations in Ohio. Regulation and hydro-modification may significantly affect certain flow characteristics but not others. The range of observed flow characteristics largely unaffected by regulation and hydro-modification are generally as follows: mean annual runoff, 10.1 to 21.2 inches; mean base-flow index, 15 to 85 percent; flow equaled or exceeded 10, 50, and 90 percent of the time, 1.7 to 4.3 cfs per sq. mi., 0.1 to 0.8 cfs per sq. mi., and 0 to 0.4 cfs per sq. mi.; average 7-day, 2-year low-flow indices, 0 to 0.4; and 2-year recurrence interval flood-peak discharge, 6.6 to 280 cubic feet per second per square mile of drainage area. Major factors other than size of drainage area that affect natural regimen of flow include: weather and climate, topographic relief, stream gradients, basin storage, surficial glacial deposits, soils, and land cover.