Erosion and transport of bed-load sediment

The mechanism of bed-load sediment transport is analyzed. The macroequations of mass and linear momentum balance that govern momentum transfer from a Newtonian fluid to rigid particles in a fluid-solid mixture are given. Stability conditions are formulated for a series of experiments which measured: the mean critical bed shear stress at Shields grain-movement condition and at the initiation of non-ceasing scour, the rate of bed-load transport, the average particle velocity, the rate of deposition, and the average length of individual steps of saltating bed-load particles. These experiments were performed in a closed rectangular flow channel using different bed slopes and bed materials. A method was developed that permits determination of the extent of the zone of bulk erosion created locally and instantaneously in a loose granular bed during highly erosive flow.