Amplification and deformation of tidal wave in the UpperScheldt Estuary
The records of HWand LW in the most upper part of the Scheldt Estuary since 1971 have been analysed together with the daily riverdischarge. The tidal range, the hydraulic head and the ratio betweenthe rising tide period to fallingtide period have been determinedfor investigating the tidal amplification, the water surface slope along the river and the tidal asymmetry. The purpose of theinvestigation is to find out if a regime shift to high turbidity and strong tidal amplification is developing in the system. The resultsof the analysis show that both the hydraulic head and the tidal amplification have increased over time. The tide in this part of theestuary is flood-dominant, but the flood-dominancy is decreasing in time. These developments of the tide can be plausibly explainedby a decrease of the river width followed by gradual deepening in the river. The most upper part of the Scheldt Estuary still behavesnormally as a not too muddy system. No decisive answer can be given whether or not a regime shift towards a high-turbid systemwith strong tidal amplification may develop. How the systemwill develop depends on the change in capacity of pumping mudtowards the upper reaches of the estuary. The increasing tidal amplitude can enhance this capacityalthough the flood-dominanceitself is decreasing. Further study is recommended to better specify the potential danger of a regimeshift to high-turbid system