Gravel Saltation: 2. Modeling

A Lagrangian model for the motion of a sediment particle in a water flow is proposed. The particle motion equation is averaged over flow turbulence, specialized to the case of coarse sediment particles saltating in water, and coupled with a stochastic model for particle collision with the bed. Model predictions of statistics of gravel saltation generally agree well with experimental observations. As an application of the saltation model, bed load transport rates are estimated from modeled mean saltation streamwise velocity and a dynamic friction coefficient. The results obtained compare favorably with typical bed load equations, but they overestimate experimental measurements of gravel transport, which would suggest that a Bagnoldean formulation for bed load transport of coarse material by saltating particles may not be valid.