Summaries Quality checking was a special point of
was guaranteed due to accurately worked out
work cycles and loading schemes.
concern, not only of the depositing equipmen
but also of the executed depositing processes
and the compaction of the deposited layers.
Evaluation of the foundation bed
The foundation bed of the Oosterschelde barrier
was completed in May 1984. It consists of a
number of packed filter layers under each pier,
with loosely dumped filter material in between.
An outline description is once more given in
this article of the filter constructions and the
way in which they are brought into place.
In carrying out this work the proper gradation
of the material was a matter of constant
concern. The covering of the mats turned out
to be vulnerable. It was torn open on two
occasions by the equipment. Certain initial
difficulties were encountered in dumping the
loose filter material, such as the thickness of
the loosely dumped layer being inadequate. The
fact that the foundation mats could be laid out
flat beyond expectation meant that tile mats
had only to be laid in three places so as to
compensate for the remaining unlevel surface.
There was less silting than expected. The
survey systems of the work ships were
satisfactory.
Evaluation of the sill construction
With sill construction we mean here the
construction of the sill in the Oosterschelde
barrier with the exception of the top layer of
very heavy boulders. The construction of the
sill in this sense was realised between August
1983 and June 1985. This was executed mainly
by the self-propelling stone depositors 'Libra',
'Ham 601' and 'MO 6010'.
These ships could perform their task in the
breaches due to a system which kept a watch
over the current speeds. The necessary tempo
Geo-morphological processes in the
Oosterschelde
The flats and marshes in the Oosterschelde ar;
of great biological importance. The hydraulic
conditions here will change considerably on
completion of the storm surge barrier. The
influence of the tide will be reduced and that >f
the waves will increase.
Research into these processes has been
combined into the GEOMOR project. It has
been endeavoured to design a model with
inventory measurements in one location whic.i
will eventually be able to forecast the
developments. Subsequently verification of tf e
results is necessary in other parts of the
Oosterschelde.
The first measurements were made in the
Autumn of 1983 on a part of the Galge flat
which is highly exposed to wave workings. The
highest transport of riverbed material was
found to occur at springtide. The erosion was
greatest under storm conditions.
Up till now the verifying measurements have
mainly confirmed these first impressions.
Current, sand and tide measurements on th<
Roggenplaat
The Roggenplaat in the mouth of the
Oosterschelde forms the natural separation
between the Hammen and Schaar channels.
The character of the current and possibly als
the geography will greatly change with the
completion of the Oosterschelde works. This is
why a series of measurements has been mad
on the situation as it is at present. One of thi
questions raised concerned the soil resistanci
Any answer to this requires extremely accurate
waterlevel data. This has been achieved with
the help of a special tide gauge, in which the
influence exerted by wave movement is
eliminated.
The measurements are supplemented with
calculations in the mathematical model DOO 1
I. This is one of the four models with which he
currents and water levels will be calculated
every 100 m and every 30 seonds when the
works are completed.
220
