barri' r the Roompot lock was initially intended The developments after 1987 will probably
to fus ction only in order to meet the needs of result in some improvement in the quality
shipp ng for the works, but later it was decided parameters,
to m <e it available for fishing boats and also
for rt reation. The hydraulic marginal conditi
ons e e the same as for the storm surge
barri Three hours of blocking the locks ten
time; a year is considered acceptable. The lock
charmer is 100 m long and 16 m wide. The sill
lies a M.S.L. -5,70 m. The chamber is closed
bysli ing doors. In the meantime it has been
deciC d to build permanent bridging over the
lock c M.S.L.+22 m.
Thee sure of the Marollegat
The s nd closure of the Marollegat in the
Oestc dam was completed in the summer of
1985 was a fairly simple job and it has been
used ar making measurements with a view to
clarify ng the processes which occur with a
closu of this kind. Use has been made of
work; ility models and of a progress model.
From ie results an indication was obtained as
to the iecessary equipment input, and with
regar to the slopes, piston production and
grain ameters. A full report will be made on
this.
It is a> ady apparent that the phenomenon
'sand and waterflow' looks different to what
hash n assumed up till now.
The cl sure gap, which was built on a soil-im
prove ent, has been partially closed first from
north a south and then going in the opposite
direct n. In the last phase auxiliary dikes were
set up in between which the gap was filled.
The w ter quality of the Oosterschelde
Since ie closure of the Volkerak in 1969 there
is no c en connection between the Oosterschel
de anr the highly polluted Rhine and Maas
rivers. Since then the water quality of the
Ooste chelde is being determined mainly by
water assing through the Volkerak sluices, the
poldei and the rivers of Brabant, by the
excha ge with coastal waters and by processes
in the osterschelde itself. The intake via the
Volke: k sluices and from the rivers of Brabant
is kept o 50 m3/s. On completion of the
comp.' tment dams the water load will decrease
by 45' and the nutrient load by 50%.
The in uence of the coastal water on the
Ooste chelde is very big. Generally, 10%
Rhine nd Maas water is still to be found in the
estuar carried along the coast by the currents.
This ir uence may possibly decrease after
1987 c a result of new morphological develop
ments rn the Voordelta.
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