LARGEST of the 13 ambitious Delta Works - Oosterscheldekering
Posted by: 
koetje1977
N 51° 36.923 E 003° 41.059
31U E 547380 N 5718483
The OOSTERSCHELDEKERING is the largest of the 13 ambitious Delta Works series of dams and storm surge barriers.
Waymark Code: WMM7RV
Location: Zeeland, Netherlands
Date Posted: 08/06/2014
Views: 47
The OOSTERSCHELDEKERING (in English: Eastern Scheldt storm surge barrier), between the islands Schouwen-Duiveland and Noord-Beveland, is the largest of the 13 ambitious Delta Works series of dams and storm surge barriers, designed to protect the Netherlands from flooding from the North Sea.
The construction of the Delta Works was in response to the widespread damage and loss of life due to the North Sea Flood of 1953.
The nine-kilometer-long Oosterscheldekering (kering meaning barrier) was initially designed, and partly built, as a closed dam, but after public protest, huge sluicegate-type doors were installed in the remaining four kilometers. These doors are normally open, but can be closed under adverse weather conditions. In this way, the saltwater marine life behind the dam is preserved and fishing can continue, while the land behind the dam is safe from the water.
On 4 October 1986, Queen Beatrix officially opened the dam for use by saying the well-known words: "De stormvloedkering is gesloten. De Deltawerken zijn voltooid. Zeeland is veilig." (The flood barrier is closed. The Delta Works are completed. Zeeland is safe.)
At the artificial island Neeltje-Jans, at one end of the barrier, a plaque is installed with the words: "Hier gaan over het tij, de wind, de maan en wij" ("Here the tide is ruled by the wind, the moon and us (the Dutch)").
The Oosterscheldekering was the most difficult to build and most expensive part of the Delta works. Work on the dam took more than a decade. Construction started in April 1976 and was completed in June 1986. The road over the dam was ready for use in November 1987.
The road was opened by the former queen, Princess Juliana on 5 November 1987, exactly 457 years after the St Felix Day's flood of 1530, which had washed away a large chunk of Zeeland, upstream of the new barrier's position.
To facilitate the building, an artificial island Neeltje-Jans was created in the middle of the estuary. When the construction was finished, the island was rebuilt to be used as education center for visitors and as a base for maintenance works.
The dam is based on 65 concrete pillars with 62 steel doors, each 42 meters wide. The parts were constructed in a dry dock. The area was flooded and a small fleet of special construction ships lifted the pillars and placed them in their final positions. Each pillar is between 35 and 38.75 meters high and weighs 18000 tons. The dam is designed to last more than 200 years.
The Oosterscheldekering is sometimes referred to as the eighth Wonder of the World. It has been declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers.
OPERATION
The dam is manually operated but if human control fails, an electronic security system acts as a backup. A Dutch law regulates the conditions under which the dam is allowed to close. The water levels must be at least three meters above regular sea level before the doors can be completely shut. Each sluice gate is closed once a month for testing. Emergency procedures are tested on pre-scheduled dates. Once the test is passed, the shutters are quickly opened again to create a minimum amount of effect on tidal movements and the local marine ecosystem. It takes approximately one hour to close a door. The cost of operation is €17 million per year.
The full dam has been closed twenty-five times since 1986, due to water levels exceeding or being predicted to exceed the three meters. The last time was on 5 December 2013. This ends the longest period of time that the dam has been left open, being 2220 days since the previous time it was closed, on the 8th of November, 2007.
Type of documentation of superlative status: It has been declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers
Location of coordinates: The location is at the artificial island "Neeltje-Jans"
Web Site: [Web Link]
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