Ebb-tidal delta morphology in response to a storm surge barrier

The Eastern Scheldt ebb-tidal delta morphology has been adapting for the past 25 years in response to the construction of the Eastern Scheldt storm-surge barrier in 1986. As a result of the barrier, there has been a decrease in tidal amplitudes, volumes, and average flow velocities, and there is hardly any sediment exchange through the barrier. Bathymetrical measurements of the ebb-tidal delta show multiple effects: (1) an overall decrease in sediment volume, (2) a decrease in morphological activity , (3) sedimentation in most channels, (4) northward reorientation of channels and shoals, and (5) an increase in wave-driven features. Some channels are showing stronger erosion since 1986. This, and the reorientation of other channels could be related to changes in the interaction between cross- shore and alongshore tide. Most of the erosion is located in shallower, wave-dominated regions, indicatting that waves have become relatively stronger. The steady erosive trend, combined with the decline of morphological activity, points toward a system dominated by relatively small and mostly negative bed-level changes. This system is still far from any kind of equilibrium, and is steadfastly adapting itself to the new hydraulic forcing regime, even though sediment transport capacities have decreased.