Influence of bed slope related sediment fluxes on morphodynamic equilibria in tidal embayments

Numerous authors have investigated the characteristics of cross sectionally- averaged morpbodynamic equilibria in well-mixed tidal embayments. In most of the contributions considering rectangular, short embayments, the divergence of the diffusive sediment flux related to the bed slope is assumed to be balanced by a sediment flux related to wave action. In the present contribution the influence of this sediment flux is taken into account and its influence on the morphodynamic equilibrium solutions is investigated. It turns out that when this sediment flux is accounted for, concave equilibrium profiles are found if the system is only forced by an M-2-tide. The concavity strongly depends on the grain size. Taking an external M-4 forcing into account, the bed-slope related flux is essential to obtain morphodynamic equation with embayment lengths of the order of 15 km. Depending on sediment properties, the prescribed relative phase and embayment length, these profiles can be convex or concave. These results are explained physically and compared to field data of tidal channels in the Dutch Wadden Sea.