Paradoxical discussions on sediment transport formulas

摘要

One of classic study topics is chosen for discussions. It is well known that bed load formulas which are proposed using Bagnold's idea and associated method are characterized by τ_*~(3/2). Structure of such formulas are analyzed by separating sediment volume and average velocity from bed-load layer. Results suggest that the sediment volume of bed-load layer increases linearly with bed shear stress and the average velocity is determined using the velocity profile over rigid beds, which yields a specific form of τ_*~(3/2). Such treatment seems unreasonable from a view point of dynamics of continuum flow field. To overcome such kind of treatment, the authors introduced a method proposed by Egashira et al. (1997) into present topics, and proposed a very different formula for bed-load estimation.