Model results indicate that a rising sea level at a rate of 2 mm/yr results in an slight landward retreat of the ebb-tidal delta of the mouth area, whereby channels and shoals undergo increased sedimenta tion over time (0.25 mm/yr on average). This sedimentation is the result of increased sand import from the offshore areas. The latter changes become stronger with increasing rate of sea level rise. In the Western Scheldt estuary, a rising sea level rather causes the redistribution of sand in this area, such that sand is deposited on the shoals and tidal flats. The overall sedimentation rate in the latter area is 0.15 mm/yr. Higher rates of SLR increase sedimentation on the shoals, which is mostly provided through deepening of channels and the reduction of the sand loss to the mouth area.
In the case that the amplitude of tidal currents remains fixed in time, sedimentation rates in the mouth and the Western Scheldt are too small for these areas to keep up with the rising sea level, which eventually might lead to the drowing of the estuarine system. However, the inclusion of stronger tidal currents increases sedimentation rates on the shoals, and it increases the volume of the deep channels, thereby counteracting the drowning of the estuarine system caused by SLR. These results suggest that the observed increasing tidal amplitudes in this area, most likely resulting from the rising sea level, is crucial for the estuarine system to keep pace with the rising sea level.