The morphology of the Western Scheidt, an estuary located in the south-west of the Netherlands, is highly dynamic. The interaction between water movement, sediment transport and bed level changes causes changes of channels and shoals in time and space. The Western Scheidt is the main navigation entrance to the Antwerp harbour as well as an highly valuable ecosystem. Changes in the morphology, due to human interference and changes in natural processes, influence these functions of the Western Scheidt. It is therefore important to be able to predict the impact of interventions on the morphological behaviour. Numerical models, with different space and time scales, are often used for this. In 2000, Svasek coastal and harbour engineering consultants bv in Rotterdam developed a twodimensional, semi-empirical morphological model of the Western Scheidt. This model connects bed level changes to water movement via an empirical equilibrium relation between dominant tidal volume and depth. Dominant volume is the tidal volume in the dominant tide phase through a cross-section per meter width. The empirical relation is applied on each grid point of a twodimensional hydraulic model. The morphological model can serve as an instrument to predict long-term morphological developments, particularly in channels. The results of the model after ten iterations are qualitatively good, but quantitatively uncertain. An equilibrium state of the bed is not reached. In this study the principle of the model and its empirical equilibrium relation are investigated in order to attain more insight in the functioning of the model.

The morphology of the Western Scheidt, an estuary located in the south-west of the Netherlands, is highly dynamic. The interaction between water movement, sediment transport and bed level changes causes changes of channels and shoals in time and space. The Western Scheidt is the main navigation entrance to the Antwerp harbour as well as an highly valuable ecosystem. Changes in the morphology, due to human interference and changes in natural processes, influence these functions of the Western Scheidt. It is therefore important to be able to predict the impact of interventions on the morphological behaviour. Numerical models, with different space and time scales, are often used for this. In 2000, Svasek coastal and harbour engineering consultants bv in Rotterdam developed a twodimensional, semi-empirical morphological model of the Western Scheidt. This model connects bed level changes to water movement via an empirical equilibrium relation between dominant tidal volume and depth. Dominant volume is the tidal volume in the dominant tide phase through a cross-section per meter width. The empirical relation is applied on each grid point of a twodimensional hydraulic model. The morphological model can serve as an instrument to predict long-term morphological developments, particularly in channels. The results of the model after ten iterations are qualitatively good, but quantitatively uncertain. An equilibrium state of the bed is not reached. In this study the principle of the model and its empirical equilibrium relation are investigated in order to attain more insight in the functioning of the model.