Effect of channel material on width-discharge relations for perennial streams, with emphasis on streams in Kansas -- a progress report

Abstract

Using consistent procedures for width measurement at established streamflow-gaging stations, data were compiled to develop a power-function relation between width and mean discharge for high-gradient perennial streams. High-gradient channels, which generally exhibit low variability for most factors influencing the width-discharge relation, were selected to define a standard exponent in the power-function equation. Regression analysis of silt-clay channels of Kansas gave an exponent similar to that determined for high-gradient streams, thus supporting the use of a standard exponent. To account for the effect of sediment on channel morphology, silt-clay percentages of bed and bank material from 98 perennial streams of the western and midwestern United States were introduced into the standard width-discharge relations. Bed and bank cohesiveness, as indicated by silt-clay content, is considered a measure of channel resistance to erosion. Multiple-regression analysis of data limited to Kansas streams yielded an equation more typical of stable conditions than that of the larger area, because widespread destructive flooding and channel widening have not occurred in Kansas recently. The regression equations provide refinement to the channel-geometry technique of estimating discharge characteristics of ungaged basins. The equations also provide a means of anticipating changes in channel morphology resulting from hydraulic structures.