Netherlands must start preparing for sea level rise now: Deltares

The Netherlands must start taking measures right now to cope with a sea level rise of over a meter by the end of this century, the knowledge institute Deltares said in a report published on Friday. That starts with governments reassessing all their major investments in residential areas and industry to make sure they won’t limit later choices for strategies against the rising sea levels, NRC reports.

It will be decades yet before the consequences of the rising sea level are clearly visible in the Netherlands. But if politicians don’t already consider what the Netherlands will look like in 50 or 100 years, the choices automatically become smaller, Deltares researcher Marjolijn Haasnoot said to the newspaper.

“We are talking about the long-term adaption task. It’s so big that you have to think about it now,” Haasnoot said. “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. You get locked in. You swim into a trap that is difficult to get out of.”

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

“We have long thought that we still have time and that the Netherlands can keep all options open,” Haasnoot said. But that is no longer true. “If part of the government now makes all kinds of choices without taking this into account, water managers will soon no longer have any options. That is what we are heading for now.”

According to the Deltares researchers, there are four ways to cope with the sea level rise, bearing in mind that draining water from the rivers to the sea will become increasingly difficult. The first way is to move along with it by moving activities, wetting the peat meadow areas in the west, leaving lots of room for nature, and, if necessary, building floating cities and large mounds.

The second option is going seaward - making a new coastline a few kilometers from the coast, with islands, a fringe lake, and space for housing and storing river water. It could also include an extreme adjustment like a dam between Norway, England, and France.

The third option is closed protection - 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 through the IJssel to the IJsselmeer.

And lastly, the Netherlands could consider open protection - temporarily closing the Nieuwe Waterweg more frequently in combination with much higher dykes along the rivers and adapted construction. This option will also require much more water to be discharged via Zeeland. “We have to put that water somewhere,” Haasnoot explained to NRC. “There has to be room for that. So you can’t build there. If you do, like many Zeeland municipalities want to, water managers can no longer choose this direction.”