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The Closure Dike.
The Afsluitdijk (English: Closure Dike) is a major dike
in the Netherlands, constructed between 1927 and 1933 and running from Den Oever on Wieringen in North Holland province, to the village of Zurich in Friesland province, over a
length of 32 km (20 miles) and a width of 90 m,
at an initial height of 7.25 m above sea-level.
It is a fundamental part of the larger Zuiderzee Works, damming off the Zuiderzee, a salt water
inlet of the North Sea and turning it into the fresh water lake of the IJsselmeer.
Previous experiences had demonstrated that till (boulder clay), rather than just sand or clay, was the best primary material for a structure
like the Afsluitdijk, with the added benefit that till was in plentiful supply in the area; it could be
retrieved in large quantities by simply dredging it from the bottom of the Zuiderzee. Work
started at four points: on both sides of the mainland and on
two specially made construction-islands (Kornwerderzand and
Breezand) along the line of the future dike.
Original plans for the works date back to the seventeenth century, but it was not until a severe flood struck in 1916,
that the Dutchparliament finally agreed. At this time Cornelis Lely (after
whom Lelystad is named) was minister of transport and
water management. He had always been an advocate of the plan and now had a chance to have the plan
executed. The single biggest structure in the project was a
32 km long dam, the Afsluitdijk ('closure dike'), protecting the Dutch from the
North Sea.
Cornelis Lely
But to test the waters the small Amsteldiepdijk was built first to connect the
island of Wieringen to the North
Holland mainland. Its construction lasted four
years and proved to be a valuable learning experience for the much larger Afsluitdijk. When
the Afsluitdijk was finished in 1932, the Zuiderzee was completely dammed off and from then
on would be called the IJsselmeer.
Total cost of the dam was about €700 million (2004
equivalent).
After damming off the sea, the next step involved creating new land, new polders. This was achieved by damming off portions of the IJsselmeer, and
then pumping all the water out. The first polder, Wieringermeer, was dammed in 1929 and fully drained in 1930. The third, the Noordoostpolder, was not fully drained until 1942 and played a vital role for the Dutch Underground
resistance during World War II, as the fresh polder offered numerous hiding places.
After the war, work was started on draining the Flevolands, a massive project totalling almost 1000 km². This area is now home
to Lelystad and Almere; the latter is the fastest growing city in the Netherlands
(in part because of its proximity to Amsterdam).
Another large polder was planned in the Markermeer, creation of which was heavily debated until plans were officially abandoned in the early 2000s. A new province,
Flevoland, was created out of the Noordoostpolder and the Flevolands in 1986, thereby completing the Works.
This newly created land has led to a great change of identity for towns like Lemmer, Vollenhove, Blokzijl, the former islands of Urk and Schokland, Wieringen and others. Kuinre suffered from the change specifically because it was cut off completely
from open water.
In 1916 the dikes at several places along the Zuiderzee (the current IJsselmeer) broke under the stress put on them by a
winter storm, and the land behind them was flooded as had often happened in previous centuries. This particular flooding,however, provided the decisive impetus to
implement the existing plans to tame the Zuiderzee. The concept of making the Zuiderzee more docile had first
originated in the seventeenth century, but the ambitious solutions sought then were not possible
given the technology of the time.
The Zuiderzee Works in the Netherlands
turned the dangerous Zuiderzee,
a shallow inlet of the North Sea, into the
tame IJsselmeer, and created 1650 km² of
land.
A new study, commissioned after doubts had arisen over
the financial feasibility of the project,
recommended that work should not only continue, but should
be accelerated. It was therefore decided to
start the next two major projects at the same time, in
1927. The most important of these would be the main dam, the Afsluitdijk (Closure-dike), running from Den Oever on Wieringen to the village of
Zurich in Frisia (Dutch: Friesland)
over a length of 32 km and a width of 90 m, at an initial
height of 7.25 m above sea-level and an incline of 25%.
Landsat photo of the IJsselmeer and surroundings. The difference between the old land (dominantly green), and the new lands (gained from the sea, dominantly
purple) is striking. Compare with the figure above.
F1-coureur Robert Doornbos with a Formule 1 car over the Closure Dike with 326 km pro
hour.
