1D vertical model for suspended sediment transport in turbulent tidal flow: Application to the English Channel

A 1D dynamic model of a tidal boundary layer flow with suspended sediment is proposed (model of sediment transport and turbulence, MoSeTT). The model includes two linearized momentum equations for the horizontal velocity components and a series of advection–diffusion equations for concentration of suspended sediment of specific size. Turbulence generated at the sea-bed is computed with the aid of a two-equation closure describing the time-space evolution of the turbulent kinetic energy k  , and the turbulent master length ℓℓ (k-kℓk-kℓ model).Special attention is paid to the bottom boundary condition for the sediment concentration, which is mixed type in order to take into account downward fluxes around times of the flow reversal.The model is applied to conditions encountered in a shallow site located in the eastern part of the English Channel. The model is forced with pressure gradients computed with a 2D vertically integrated tidal model covering the eastern English Channel and the southern part of the North Sea. The tidal currents and the total suspended sediment load predicted by the model are compared with the field data collected over two levels at the water column. The vertical structure of flow properties is fairly well predicted by the present model. Better results are found at the measuring point located farther from the coastline where advective terms can be reasonably neglected.