Friday, December 1, 2023

Sea level rise – Can a huge dam save the Netherlands?

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More than half of the inhabitants of the Netherlands live below sea level – ten out of 17 million people. How dangerous this can be was shown in 1953 during the worst North Sea storm surge of the 20th century. “Our whole family climbed onto the roof,” remembers Ria Geluk, who was six years old at the time and lives in the village of Ouwerkerk in the southwestern province of Zeeland.

The flood disaster

“Suddenly the stable right next to the house collapses.” All the cows and horses drown in the flood and the family has to watch. Then they try to save themselves from this fate. They cover the roof in the hope that the attic could serve as a raft if the apartment building beneath them also collapses.

Ria Geluk and her parents are lucky. After two days of endurance they are saved. “But my grandparents and my aunt,” says Geluk, “they drowned in the house next door.” More than 1,800 people died in this storm surge in the Netherlands in 1953.

In demand as a hydraulic engineer all over the world

Since then, the Netherlands has massively expanded flood protection. They have raised the levees and built kilometers of storm surge barriers all along the coast. For example, the Oosterschelde storm surge barrier was built through the middle of a nine-kilometer-long inlet where the tides are high and low.

After protests from the population, the spearwork was then designed for environmental reasons so that the water can continue to flow in and out. In this way, the ecosystem and thus also the lucrative oyster farming are preserved.

The Oosterschelde storm surge barrier can be seen in the picture.


Oosterschelde storm surge barrier: It is only closed in an emergency, so the coastal ecosystem with ebb and flow is preserved.


The construction of this facility was so complex that it was later described by international engineers as the eighth technical wonder of the world. This has further strengthened the Netherlands’ reputation as a nation of gifted water engineers.

Ria Cheluk, the survivor of the great flood disaster, proudly says: “Our people are in demand all over the world: in Venice, in Saint Petersburg, in Louisiana and at the airport in Singapore – they plan and build everywhere.”

Current dams could soon reach their limits

But now a new, much bigger problem is facing the Netherlands: rising sea levels due to global warming. Depending on how much CO₂ we continue to emit, sea levels will rise by 30 centimeters to one meter by 2100 – according to current research. This means that many expensive systems are reaching their limits. Also the Maeslant storm surge barrier at the port of Rotterdam, which was only built in 1997.

The Maeslant barrage can be seen in the picture.


Maeslant barrage at the mouth of the Rhine near Rotterdam: Normally it is open. On average, a ship enters the port of Rotterdam every seven minutes.


“This system can only withstand half a meter of sea level rise,” says Harold van Waveren. He is the flood risk expert at the Dutch water authority Rijkswaterstaat.

However, the protection of the coast can be improved by massively expanding or converting the existing facilities. This is already being planned, says van Waveren. “At least two to three meters of sea level rise can be managed, probably even five meters.”

The greatest uncertainty lies in Antarctica

However, the Netherlands is not yet on the safe side. Because there are great uncertainties as to how quickly and how high sea levels will actually rise. In particular, it is unclear to what extent the melting process of the gigantic ice masses in Antarctica has already started.

“We cannot therefore definitely rule out a two to five meter rise in the next 127 years,” says climate scientist Aimée Slangen from the Dutch marine research institute NIOZ. She worked on the current IPCC report.

But that’s not all: the increase will not stop after 2150. The sea will continue to rise. “Science is certain of that,” says Slangen. The sea is likely to rise by two to six meters in the coming centuries if the 1.5 degree climate target is achieved.

If not, there are significantly more. The researcher hopes that the global community will get the climate problem under control so that the Netherlands can be saved by increasing the existing dams.

A gigantic dam far off the coast

“That’s not enough,” says Dick Butijn, “we need a new dam 15 to 20 kilometers off the existing coast.” Butjin is an electrical engineer and promoter of the so-called de Haakse sea dike. Where the sea is now around 20 meters deep, a three kilometer wide wall of sand is to be created.

This would then be up to 20 meters above today’s sea level. Lakes would then be created between the current and the new coast. Over time these would become freshwater lakes because they are fed with water by the Rhine and other rivers.

If the sea level has risen by a few meters, the Rhine can no longer flow into the sea. “We then have to pump it up into the sea over the new dam,” says Butijn. Thanks to locks, ships should still be able to get from the sea into the Rhine. There should also be stairs for the fish and ecological compensation areas.

The picture shows the plan for the De Haakse sea dike with freshwater lakes, airport and wind turbines.


Plan for the De Haakse sea dike with freshwater lakes, airport and wind turbines.

Dick Butijn

It would be a project of the century. “I expect costs of a billion euros per year,” says Butjin, “a rich country like the Netherlands can afford that.” External experts are currently clarifying the feasibility of this project.

However, if sea levels continue to rise, the dam would have to be expanded further. “In the south to Calais in France, in the north to Sweden,” says Butjin, “we would have a European protective dike for up to 15 meters of sea level rise.” These are dimensions that are hardly imaginable today. But Belgium, Germany, Denmark and the entire Baltic Sea region would also be protected from sea level rise.

“It’s not politically feasible today.”

But the time doesn’t seem ripe for this gigantic project yet. “It’s not politically feasible today,” says Jeroen Aerts. He is a professor of water and climate risks at the Free University of Amsterdam and advises governments, banks and insurance companies worldwide on flood protection.

The rise in sea level is still not visible enough and is still not threatening enough for most people. “We are confronted with so many other crises and problems,” says Aerts, “such a dike project is not currently being seriously discussed.”

In the long term, however, the project could attract more attention. “But you would have to implement it little by little,” says Aerts. For example, Amsterdam Airport Schiphol could first be relocated to an elongated island in the sea. This has been discussed for a long time. The airport island would then be a first component of the dam project.

The controversy over the giant dike

From an ecological point of view, the giant dam would be problematic. “Animals and plants in the coastal area would disappear with the loss of ebb and flow,” says Aimée Slangen from the marine research institute NIOZ, “we would largely destroy these ecosystems.”

“We can’t wait any longer”

The promoter of the giant dike, Dick Butijn, says that ultimately it is about the future of the Netherlands: “We can’t wait any longer. A dike like this cannot be built in just a few decades.” And Ria Geluk, the contemporary witness to the storm surge of the century, also emphasizes: “We have already done so many studies, now we finally have to act.”

As long as people have dry feet, they don’t see the problem.

But she also sees that the problem does not seem urgent for most Dutch people. Sea level has only risen by 20 centimeters in the last 115 years. “As long as people have dry feet,” says Geluk, “they don’t see the problem.” The currently extremely good protection of the Dutch coast means that awareness of the dangers is dwindling.

Geluk therefore wants the memories of the flood disaster 70 years ago not to be forgotten. Together with other people involved, she founded the so-called Watersnoodmuseum. It is located in Ouwerkerk by the sea, where the last of the destroyed dikes was closed again ten months after the devastating flood.

The 76-year-old woman stands next to the museum and looks out to sea. She still goes swimming regularly today. “I love the sea, it’s so beautiful,” she says, letting her eyes wander, “but we must never forget that the water is always stronger than us.”

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