A new depth-averaged exploratory model has been developed to investigate the hydrodynamics and the tidally averaged sediment transport in a semi-enclosed tidal basin. This model comprises the two-dimensional (2DH) dynamics in a tidal basin that consists of a channel of arbitrary length, flanked by tidal flats, in which the water motion is being driven by an asymmetric tidal forcing at the seaward side. The equations are discretized in space by means of the finite element method and solved in the frequency domain. In this study, the lateral variations of the tidal asymmetry and the tidally averaged sediment transport are analyzed, as well as their sensitivity to changes in basin geometry and external overtides. The Coriolis force is taken into account. It is found that the length of the tidal basin and, to a lesser extent, the tidal flat area and the convergence length determine the behaviour of the tidally averaged velocity and the overtides and consequently control the strength and the direction of the tidally averaged sediment transport. Furthermore, the externally prescribed overtides can have a major influence on tidal asymmetry in the basin, depending on their amplitude and phase. Finally, for sufficiently wide tidal basins, the Coriolis force generates significant lateral dynamics.

@en

The tidal flow in an estuary, and consequently the morphodynamics and ecology, is highly dependent on the basin geometry (Ridderinkhof et al. 2014).The characteristics of tidal wave propagation in prismatic basins are well known, and also the effect of converging basins has been studied to some depth. The influence of tidal flats on tidal wave propagation has been studied using 1D models, while in this paper, both a 1D and a 2D model will be applied. The latter approach allows to account for the water motion above the tidal flats, in contrast to a 1D model where the tidal flats are modelled as storage areas.@en