Sandfill-test of the low reservoir basin of the
Krammer Sluices
The question to close the compartment dams
partially with hydraulic sandfill is still under
consideration. To gain a better insight into the
effect of this, and in order to determine more
accurately the loss of sand, a trial closure has
been made under circumstances which were
easy to check.
A gap of 100 x 150 m. was made in the
embankment enclosing the low reservoir basin
of the push-tow sluices in the Philips Dam, in
which gap measuring equipment was placed
beforehand. The gap was filled hydraulically
with sand. This test, which was performed in
the summer of 1979, supplied certain useful
indications. In actual fact, the closure was
achieved so rapidly that only part of the
measuring programme could be executed.
Operating the Krammer Sluices
A sluice-complex comprising two sluices for
shipping and two sluices for yachting will be
built in the Philips Dam. Both sections of the
sluice-complex will be separately operated
from two different central control rooms. In
order tot operate these huge shipping-sluices a
control room has been designed, which will be
centrally located to provide a good view of the
shipping traffic.
However, where this view is obscured, monitors
will be used to receive the relevant data. The
sluice-gates and the complicated fresh
water/salt water separation system will be
operated by an ingenious 'steps-button'. In
addition, radio equipment will be available to
communicate with the ships.
The operating equipment for the yachting
sluices will be simple; particularly, as it is felt
that the crews of yachts prefer a more direct
contact with the sluice-operators.
The design of the weir in the Grevelingen Dam
At the end of Lake Grevelingen a
discharge-sluice will be built which, during the
time when the compartment-dams are closed,
can assist in controlling the salinity at the rear
of the Oosterschelde basin. At a later stage,
this sluice can be used to maintain the water
quality of Lake Grevelingen.
This sluice, known as the 'Flakkee
Discharge-sluice', will function as a syphon.
The syphon is so constructed that the watershed
between Lake Grevelingen and the
Oosterschelde remains unchanged as long as
no discharge is started. By creating a vacuum
512
in the syphon-pipe, the waterparting will cease
and a continuous flow of water will start, which
will only be stopped by opening a valve in the
syphon, thus discontinuing the working of the
syphon.
Six of these types of syphon-sluices will be
placed next to one another. They should be
completed in 1983.
The vegetation on the mud-flats bordering the
Oosterschelde and the Krammer-Volkerak
The vegetated mud-flats along the
Oosterschelde and the Krammer-Volkerak
greatly enhance the natural values of the area.
Based on an aerial survey, made in 1978,
vegetation maps were recently published in
order that in future the changes taking place in
these areas after the Delta Works have been
completed can be registered. In future, the
present tidal area of 1,700 ha will be reduced to
600 ha.
To what extent this area will remain saline
depends entirely on the management of the
Oosterschelde barrier.
The Delta-dikes in the northern part of the
province of Noord-Holland and on the isle of
Texel
According to the Delta Act, safety measures
should not be limited to the Delta in the
south-western part of the Netherlands, but
must also include raising of the dikes in other
areas, inter alia, in the northern provinces. For
a long time nothing has been said in this
Quarterly Report about the works of the Delta
Plan in the northern provinces; this is being
remedied in this article. A historical review is
given from 1975 onwards, in which particular
attention is paid to the raising of the dikes on
Texel, an isle that belongs to the province of
Noord-Holland.
