What can and should the Netherlands do in the event of rising sea levels? ‘We can’t go on like this. Build in higher realms’

No, the sea level has not yet risen one or two meters and it will be decades before the consequences show. But, says Marjolijn Haasnoot, if politicians do not already consider what the Netherlands should look like in fifty or a hundred years, the choices will automatically become smaller. Haasnoot: “We are talking about the long-term adaptation task. It’s so big you have to think about it now. Some of the investments we are making now determine whether that challenge will become even greater. And they reduce your ability to adapt to sea level rise. That’s a lock in. You swim in a trap, it is difficult to get out of it.”

Haasnoot is a researcher at knowledge institute Deltares and one of the lead authors of a study published on Friday into what measures the Netherlands can now take to prevent sea level rise, which will happen anyway. The main message, as the cliché goes, is that the future has now begun. Haasnoot: “We thought for a long time that we still have enough time and that the Netherlands can keep all options open. But so many investment decisions are made today that I’ve changed my mind. If part of the government now makes all kinds of choices without taking this into account, water managers will soon no longer be able to choose. That is what we are now heading for.”

What measures might we regret later?

“In the peat meadow area, such as near Gouda, the water level is being adjusted in order to be able to build residential areas. Neighborhoods are also being built in Utrecht and Leiden. Arnhem wants to build in the floodplains. Does this take into account adaptation to sea level rise? Investments for the energy transition, such as the possible construction of hydrogen factories in the port of Rotterdam, should also consider the consequences for water management.”

Do you advocate a kind of ‘sea level rise test’ for investments?

“A great idea. You should then take it more broadly and keep asking: does this investment contribute to a sustainable design in the Netherlands, given the rise in sea level, but also drought and extreme precipitation? The Dutch water machine is going to falter. We can’t go on like this, it will break down. We are reaching the limits. And everyone is saying that, but the practice is complex.”

Should the government make those choices for major investments from now on?

“The Utrecht region has a problem that they want to solve. But you may indeed have to solve the problem elsewhere. And say: we are building these neighborhoods elsewhere in the Netherlands. I once started my work at RIZA, at the time a knowledge institute of Rijkswaterstaat. That had been transferred from The Hague to Lelystad and that was not for nothing; they wanted employment there.

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“You can do something like that now. If you know that that meter of sea level rise and more is coming, you can avoid ending up in a lock-in, and not build in risky places. Then rather build in higher areas, in the east.”

The Deltares researchers describe their work as a kind of puzzle, or rather: making pieces with which others can make a puzzle. There are roughly four ways to cope with sea level rise, bearing in mind that it is becoming increasingly difficult to drain water from the rivers to the sea when the sea level rises.

The first way is to move: relocation of activities, wetting the peat meadow areas in the west, plenty of space for nature and, if necessary, floating cities and large mounds.

Second Seaward: a new coastline a few kilometers from the coast, with islands and a fringe lake with space for housing and the storage of river water. Or an extreme adjustment like a dam between Norway, England and France.

Third protect-closed: closing off the Nieuwe Waterweg near Rotterdam and discharging river water to the sea with a gigantic pump system, possibly in combination with discharging more river water to the sea via Zeeland or more water through the IJssel to the IJsselmeer.

Fourth protect-open: the more frequent temporary closure of the Nieuwe Waterweg in combination with much higher dykes along the rivers and adapted construction. In this case too, much more water will probably be discharged via Zeeland. Haasnoot: “We have to leave that water somewhere. There has to be room for that. So you can’t build there. If you do build there, as many Zeeland municipalities want, you can no longer make the choice as a water manager in this direction.”

So Zeeland must now ban construction because we may need that space in fifty years’ time?

“If you don’t do that or build without modifications, you let people buy a house that they have to leave. If you don’t think about it now, those investments will soon be for naught. Banks and insurers now also realize that this will affect them, and will say to the next generation: you will no longer get a mortgage or insurance.”

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Which choice of the four directions is the most obvious?

“There is a lot of interest among engineers in the seaward direction, and in protecting the variants. The question then is what to do with the river water. What we found shocking ourselves are our calculations that show that, if you close off the coast when the sea level rises by two meters, and you allow twice as much water to flow through the IJssel as now, for example, the water levels in the underlying river area will still be higher. become. That means we have to pump, pump and pump some more. Pumps with a capacity of at least ten thousand cubic meters per second, covering six to ten kilometers of space on the west coast. That is not impossible. Our colleagues at TU Delft know how to handle this. But it does take a lot of energy.”

Wouldn’t it then be easier to ‘move with’ the sea level?

“That direction fits in with the strategy that we have to live with water, as we used to do with mounds, and recently with the Room for the River project. In addition, moving along is also good for other goals, such as restoring biodiversity and combating climate change, such as rewetting peat meadow areas. On the other hand, it will be difficult not to build somewhere. But you don’t have to opt for full flexion right now, because you can also record parts of this variant in the other directions.”

But whichever direction the Netherlands chooses, in all cases it is humans who organize the space.

“I was recently on the Oosterscheldekering. There is on a monument: Here are the tide the moon the wind and we. That recognizes that we have overcome something, but also that we are moving along. That is beautiful. The final strategy will probably be a mix.”

A version of this article also appeared in

the newspaper of September 30, 2022