corresponds with about 11% of the area of the Nether
lands.
Based on my own experiences, gained with the realiza
tion of about 15 projects, I assume the amount spent on
this since 1975, to be about D.fl. 75 million.
Now that the economic recession becomes more and
more obvious in our country and the government is
forced to economize, there is some concern regarding
the continuation of this important „unimapping pro
ject". We therefore advocate the use of money meant
for employment, in order to be able to continue these
activities. The use of this sort of money offers excellent
possibilities to involve young unemployed people in
measuring and drawing activities, as is shown with the
large scale basic map - Leeuwarden.
Considering this aspect and also taking into considera
tion the fact that with the Cadastre itself as well as with
bureaus occupied with surveying and mapping activi
ties are decreasing, as a result of the diminishing econ
omic activity, I advocate an initiative of the government,
directed at the financing of the large scale basic map of
the Netherlands. Such an investment will breakthrough
the present financial deadlock and add to the "infra
structure" of government and semi-government de
partments, and will have its use for years.
Fig. 2. Unemployed young people surveying the large
scale basic map of Leeuwarden
Activities at sea
Of old our country is known because of its knowledge of
hydraulic engineering, dyke building and reclamation of
land.
In the thirties the Zuidersea was closed by means of the
construction of the Barrier Dam. Because of this respec
tively the Wieringerwaard, the N-0 Polder and O- and
Z-Flevoland came into being. As a result of the flood of
1953, with which large parts of Zeeland, N-Brabant and
Z-Holland were flooded and almost 2000 people were
killed, a special law was accepted which provided for
hydraulic constructions, among others directed at clos
ing of the Zeeland and Z-Holland watercourses.
At the moment the most extensive and spectacular part
is being carried out, namely the closing of the „Ooster-
schelde". This pierdam, which lets seawater pass
through, acts as a retaining wall with storm tides, and
will consist of 66 piers, linked together by bars and
lintels. Between the pillars there will be steel slides that
can be moved up and down.
The measurement of a pier at the base are 50x25 m, the
maximum height is about 40 m. About the check on the
dimensions with regard to pierbuilding a report has
been made at the NGL-congress in October 1981.
Surveying departments of large contracting companies
that are operating on an world-wide scale are working
on the solution of the problems concerning the exact
setting out of the piers, in close cooperation with the
Survey Department of the Ministry of Public Works.
230
Also they aim at rendering services to oil-companies
and constructional companies that develop off-shore
activities.
This rendering of services mainly consists of:
- supply of personnel to operate hired instruments;
- presentation of collected information in the shape of a
report or maps;
- advice with the selection of equipment, surveying de
sign and execution of the measurements.
The Dutch companies aim at the North Sea in the first
place. The activities here have increased largely since
the end of the sixties. The activities comprise position
of:
- ships for seismic research
-drilling platforms, the position required depends on
seismic research;
- ships for hydrological research, on which at the same
time depth measurement and side scan sonar surveys
take place, as well as research into the composition of
the seabottom by means of the subbottomprofiler;
- inspection ships, with which pipe lines and platforms
are inspected.
In the past period a lot of experience was gained by
Dutch companies in the North Sea area. Today they are
working throughout the world, employed by oil compa
nies and constructional companies.
Dutch companies abroad
The „world wide" offering of specialized services is not
limited to hydrography alone. Dutch engineering firms,
whether or not, they are connected with „NEDECO" are
active throughout the world. The Dutch companies in
our professional field are active in complex projects, or
in purely surveying, photogrammetric ones. They have
at their disposal highly trained educated and experienc
ed personnel as well as very modern measuring devic
es, and advanced processing equipment. Interactive
graphic processing of measuring data is already applied
in practice with a number of companies.
Our national company concerned with aerial surveying
has completely automated the making of maps.
The exhibiting companies, here all represented, are
happy to have been able to contribute to this day of
study.
Fig. 3. Positioning of a rig in the North Sea
NGT GEODESIA 82
