By Rafe Calder
Most dams exist to stop water. The Oosterscheldekering, in the Dutch province of Zeeland, was built to stop water only on the worst days. For the rest of the year it stands open and the tide runs through it twice a day.
Why it exists
Several sources start in 1953. A visitor-site entry from ERIH, the European Route of Industrial Heritage, says a storm surge on 1 February 1953 flooded almost 200,000 hectares in Zeeland, with tide levels reaching 4.20 metres above normal. The Dutch parliament passed the law for the Delta project in 1958, according to ERIH and to Wikipedia’s article on the Delta Works, which says the works as a whole ran from 1954 to 1997.
Wikipedia’s article on the barrier says the Delta Works were a response to that flood. It is the largest structure among them, and the second longest dam in the series after the Oesterdam.
Why it is open
The Watersnoodmuseum, the flood museum in Zeeland, says the original plan was a full dam. That would have turned the Eastern Scheldt fresh and stagnant and harmed its shellfish, seals and birds, so a commission advised a semi-open barrier that keeps the tides flowing. Rijkswaterstaat, the Dutch state water authority, says the open design was chosen to protect the natural environment and the fishing industry, and that the water stays saline. Wikipedia says the first design was closed, and that after public protests sluice-gate doors were installed.
The sources agree on the reason and describe the decision in different words, as a commission’s advice or a choice for the environment. They also differ on timing.
The numbers, side by side
The sources agree on a few figures and not on others. We do not choose.
- Piers: 65 concrete piers or pillars (Wikipedia, Watersnoodmuseum, Rijkswaterstaat, ERIH).
- Gates: 62 steel gates (all four).
- Total length: 9 km (Wikipedia, Watersnoodmuseum, Rijkswaterstaat).
- The part that closes: 3 km (Watersnoodmuseum, Rijkswaterstaat).
Dates in order
- 1 February 1953: the storm surge (ERIH).
- 1958: the Delta law (ERIH, Wikipedia).
- 4 October 1986: official opening (Wikipedia, Watersnoodmuseum, Rijkswaterstaat).
When it closes
The gates close when the water is expected to reach about 3 metres above NAP, the Dutch reference level, says the Watersnoodmuseum, and Rijkswaterstaat agrees. Rijkswaterstaat and the Watersnoodmuseum say it closes about once a year on average.
Neeltje Jans
Wikipedia says Neeltje Jans is an artificial island built in the estuary to help with construction, which later became a visitor centre and maintenance base. The Watersnoodmuseum says it was the main construction site, that the automatic “red button” which lowers the gates is in the Topshuis there, and that a spare pier is on show as a climbing wall. ERIH lists the visitor offer: an exhibition area with photos, models and presentations on flood protection, films on the 1953 disaster and the building of the barrier, and views of the gates from inside the structure.
What kind of sources these are
Wikipedia; a state water authority’s own page; a flood museum’s article; and a heritage network’s entry for the visitor site, which is promotional in places. None of them gives costs we would use, and we left the money out.
Quick answers
Why is the Eastern Scheldt barrier open? According to Rijkswaterstaat, the Dutch water authority, the open design protects the natural environment and fishing; tides still ebb and flow and the water stays salty.
How many gates does it have? All four sources we read give 62 steel gates between 65 piers, with the gates normally open.
When does it close? The Watersnoodmuseum says it closes when water is expected to reach about 3 m above NAP.
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