Summaries
Dr. H. L. F. Saeijs
Ir. Tj. de Haan
The significance of the Delta project for the
safeguarding of the Netherlands against the
sea
The article gives an historical survey of the
geological development of the Netherlands
since the end of the last glacial period. Mans
role became increasingly evident in landscape
formation.
Disasters and flooding make a deep
impression on the generation which is
immediately affected and also on the one
which follows. In time however this subsides.
The Delta project was the Dutch answer to
the disaster of 1 953, when current safety
precautions proved insufficient against the
high tides. This project resulted in a structural
improvement of the safety system, by way of
blocking many estuaries and shortening the
coast - onsiderably.
But also ways of thinking about safety
matters changed. A statistically proven and
universal safety criterion was developed,
qualified by social and economic consider
ations, which ultimately led to the setting of
'timeless' criteria for the safety of coastal
defences.
The Delta project also evoked rapid develop
ments in technical and hydraulic engeneering.
In the meantime the sea steadily rises and the
erosion of the North Sea coast continues. Our
task for the future clearly lies in maintaining
the degree of safety which has been
achieved.
Conditioning. Lessons of 20 centuries of
Hydraulic Engeneering and Water
Management
The present appearance of the Netherlands is
the result of 2000 years of close co-operatior
of man and nature.
During the 20th century some strong
measures were indicated to safeguard the
very existence of the country: it was threat
ened by total erosion. As counter measures
we first had the Zuiderzee works, and after
wards the Delta project. With the latter
project it became clear that water systems
require as much care as any other, not only
because they provide drinking water and
recreation facilities, but also for their own
sake. Planned transformation of the ecology
together with spontaneous natural develop
ments can result in a balanced strategy,
known nowadays as 'conditioning'.
An important instrument here is the formatioi
of compartments: dividing the wet part of the
country into subsystems with their own infra
structure; each of which must be regulated a
a whole: water body, bedding, shores and
ground water. Subsequent governmental
memoranda concerning Water Policy show
how the thinking about water developed: the
approach became more and more functional,
and the preservation of water systems
became a matter of growing importance.
During the last 25 years a great number of
hydraulic constructions has been built, each
functioning as a steering device for large
stretches of water upstream and downstrearr
sometimes unintentionally. These works
should therefore always be carefully super
vised by ecologists until long after their
completion, if they are to function as
intended.
Drs. S. P. van der Zee
The Delta project. Some socio-economic
considerations, especially with regard to
Zeeland
At the time of industrialisation in the Nether
lands, in the 19th century, Zeeland failed to
keep pace. This was mainly due to the
isolated position of the islands.
Even after World War II Zeeland remained
principally agararian. When this province wa:
struck by disaster, in February 1953, the
future looked bleak. Nevertheless the famous
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