Bedload Model for Nonuniform Sediment

Abstract

AbstractIn this study, a bedload model for nonuniform sediment is developed considering the density function of sediment entrainment with no active layer. The model is formulated based on physical considerations, dimensional reasoning, regression analysis, and laboratory data. Four parameters are incorporated in the model formulation, namely the Shields stress τ*g′, the critical Shields stress τ*cg, the Kramer coefficient of uniformity cu, and the relative grain size (size of the jth grain fraction to the geometric mean size, dj/dg). The model collectively accounts for the hiding effects and the variation of the transported bedload material fractions from the surface and subsurface material. The findings of the study show that at low values of τ*g′/τ*cg fractions within the range of 0.3<dj/dg<3.0 are present with larger amounts in the transported bedload material than in the substrate, whereas fractions finer or coarser than that range are present with larger amounts in the surface layer than in the subst...