Hydro-ecological relations in the Delta Waters

discharged through the mouths of the estuaries to the North
However, local variations were apparent, with further erosion taking
place in the deeper tidal gullies and corresponding increasas in
sedimentatton occurring in the shallows. Moreover, sea-borne sediment
was deposited in the western part of the Delta. The finer type of
fluvial sediment was only deposited in more sheltered locations, with
the majority of it flowing tkouah to the RarM Sea. Under the
influence of the prevail*
sediment was carried northwerds, where w e
10%-shore current this fine fluvial
of it was deposited ia the
Wadden Sea, an extensive w e s l area ~ in the north of the Netherlands.
Successive closures in the Delta area produced chenges in the flaw
distribution, while flow rates tended to decline as a result of the
complete or partial loss of tidal motion. =is Led to tde formation of
new se-ntation
areas witain the Delta regfoil. By 1965 the central
section of tXe Delta vaS no longer sublect fa the influence of the
Rhine and Ruse. In 1965 and 1969 resptpectively the Grevelingen and
Eastern Scheldt estuaries were effectively &coupled from these two
rivers. The closure of the Harinmliet estuary in the northern section
of the Delta had the effect of reducing tidalmotion over the whale oi?
this area. Xn the sautb, the Western Scheldt estuary remained Largely
unchanged, although the sand bars in the estuarp *ere dug out in the
1970's to improve the shipping route to Antwerp (Belgium). Finally, in
1987, work in rhe eastern past of the Delta led to the fomation of a
separate freshwater lake (Lake Zoom3 in the Eastern Scheldt, irith the
spe~ific aCm of imprwing water supplies for agricultural purposes.
Lake Zom is being flusked out with frwb water from the Eollarids Diep,
The overall eff&t of all these hydraulic engineering projects has been
to change significantly the distribution of river water, which has had
implications for the transport of fluvial sediment. Recent measurements
of the transport of fine fluvial aediments are shown in tern of tons
per year in Figure 3. This fi~uze also gives the yearly irccumulation of
river sediment at: particular locations. Region I represents the
southern lower reaches of the Rhine and the lover reaches of the Meuse.
Following the closure of the Haringvliet estuary, flov rates in the