Characteristics of Sediment Transport Process on Duned Beds Analyzed by Stochastic Approach

Abstract

When the bed is covered by sand waves such as dunes or ripples, the relationship between bed load transport rate and hydraulic parameters becomes different from the one valid in the case of flat bed conditions. Although the sediment motion in such an undulated bed is much complicated, fortunately it is so connected with the geometrical properties of bed configurations that one can describe the bed load transport process, not only the averaged properties but also the variational characteristics, by making use of a stochastic model for bed load dispersion. In this paper, the characteristics of the rest period and the step length in the case of lower regime bed conditions, which are essential elements of the stochastic model and represent he probabilistic characteristics of behaviors of individual bed load particles, were investigated in relation to the statistical properties of sand waves, and a generalized stochastic model which can be applied to such an undulated bed was derived. The theoretical results and estimations in this study were verified by the previous experimental data.