Modelling Sheet Flow Sediment Transport Using Convolution Integrals

Existing simple, practical models used to predict the transport rate of cohesionless sediment in the sheet flow regime have obvious shortcomings. They generally relate the transport rate directly to the velocity just outside the boundary layer or to an estimate of the instantaneous bed shear stress. Such models neglect important unsteady flow effects such as phase lags between the flow forcing and the bed shear stress and between the bed shear stress and the transport rate. Most also fail to account for the influence of the acceleration time history on the magnitude of the bed shear stress. In this paper a new simple, practical model is developed that aims to provide similar prediction accuracy as more complex process-based models without the computational expense. Convolution integrals are employed to obtain solutions for the governing differential equations in the time domain while accounting for the important unsteady flow effects.