Modelling tidal currents in a sediment stratified idealized estuary

A numerical modelling study on the effects of sediment-induced stratification on tidal currents is conducted for an idealized tidal estuary with a muddy seabed. The numerical model is a three-dimensional oceanic sediment transport model capable of predicting dynamics of Newtonian fluid mud layers due to coupling of the sea water density and suspended sediment concentration. The model uses a reparameterized bottom drag coefficient Cd that incorporates a linear stability function of flux Richardson number Rf. The study has shown that the sediment-induced stratification in the bottom boundary layer (BBL) reduces the vertical eddy viscosity and bottom shear stress in comparison with the model prediction in a neutrally stratified BBL. In response to these apparent reductions, the tidal current shear in the water column is increased in the estuary.