Bed Load Transport of Sediment Mixtures

Abstract

Experiments were conducted on alluvial beds of four sediment mixtures having different arithmetic mean diameters and standard deviations. The bed load transport rates of individual fractions were measured. Einstein's method, Proffitt and Sutherland's method, and Misri's method of calculation of the bed load transport of individual fractions for sediment mixtures were checked with carefully collected laboratory data. By analyzing the data on lines similar to those of Misri, et al., their method of calculation of the bed load transport rate for individual fraction is modified to make it applicable over a wide range of parameters. The relationship between the dimensionless grain shear stress and the dimensionless bed load transport rate developed by Misri, et al., for uniform sediments was made applicable to sediment mixtures by introducing a multiplying correction factor. The parameters affecting this correction factor were identified and a relationship obtained for the same by analysis of an extreme amount of laboratory and river data. Use of this factor along with the transport law for uniform sediments enables determination of the rate of bed load transport of the individual fractions of a mixture.