The rate of deposition of fine sediment from suspension

Standard depth-integrated models of sediment dynamics predict that concentrations of suspended fine sediment should decay at a characteristic rate that is controlled by the particle settling velocity and the depth of the water. In contrast, a model which resolves the processes of settling and dispersion in the water column has suggested that this decay rate should be independent of the settling velocity, and is controlled by dispersive processes in the water column. By revisiting the problem of sediment dispersion and settling following a point release of material, we resolve this discrepancy and confirm that depth-integrated models capture the correct physical behavior.