ABSTRACT:
Thirty-two cross-sections on five tributaries of the Washita River in southwestern Oklahoma were resurveyed in 1985 to determine changes in the channels since the installation of floodwater-retarding reservoirs 15 to 30 years earlier. The crosssections on East and West Bitter Creeks had an average increase in bankfull area of about 9%. Channel depth increased 2% on West Bitter Creek and 9% on East Bitter Creek. Much of the deepening on East Bitter Creek was caused by an overfall working upstream from a channel-straightening project. There was no change in the average hydraulic radius for bankfull flow and no significant change in channel vegetation on the Bitter Creeks. The Little Washita River channel parameters increased as follows: area, 3%; depth, 12%; and R2/3 (hydraulic radius2/3) for bankfull flow, 3%. Winter Creek and Sandstone Creek had oversized channels due to extreme erosion before reservoir installation. Cross-sectional areas in the two creeks declined 9% and 5%; depth increased 12% and 8%, respectively; and R2,3 for bankfull flow declined 5% in each of these channels. Grass, sedges, brush, and trees now cover most of these two formerly barren channels. But there is little chance of overbank flow from either channel in the next decade because of their large cross-sectional areas.
Footnotes
R. R. Schoof is a hydraulic engineer, G. A. Gander is a mathematician, and N. H. Welch is a soil scientist with the Water Quality & Watershed Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture. Schoof is at P.O. Box 1430, Durant, Oklahoma 74702; Gander and Welch are at P.O. Box 400, Chickasha, Oklahoma 73018.
- Copyright 1987 by the Soil and Water Conservation Society
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