Hydro-ecological relations in the Delta Waters

Figure 3 Developaent of lengshore bars and tidal channels on the
Grevelingen ebb tidal delta 1970-1980 (Kohsiek and Mulder.
1989)
3.4 00s terscbelde
The Oasterscbelde basin was directly influenced by the construerion
works in other estuaxies. Due to the b~lding of the Greuelingen Dam
(1965) and Volkerak Dam (1969), the tidal prism of the Oosterscbelde
increasad cirna 6 - 8% aver the period 19.60 - 1983 (Van den Berg,
19861. A considerable erosion and widening of the channels has been
observed over this period (Van den Berg, 19861, which is in accordance
with the expected geomorphological reaction (conform Fig. 4A).
Construction of the storm surge barrier (1986) and af the landward dams
(Desterdam, 1986. and Philipsdam. 1987) has disiurbe* these tendencies.
Since 1986 the tidal volume of the Ooscerschelde has decreased by 302;
tidal current velocities have dimiaished by a simLlkr percentage and
the tidal range by some 1ZZ. This reduction in tidal influence, most
probably bas initiated a process of channel sedimentation and shoal
erosion (conform Fig. 41)). However, no gevmcrpholdgical absematirms
are available yet to confFnn this.