Netherlands needs up to €33 billion to shore up flood defenses; far more than estimates

More of the Netherlands' dikes, flood defenses, and dams require reinforcement than expected. In 2014, the government estimated that about 1,500 kilometers of these structures needed strengthening. Now, it looks like about 2,000 kilometers need work by 2050, outgoing Minister Mark Harbers of Infrastructure said on Wednesday.

Exactly how much extra this larger task will cost is not yet clear, Harbers said. In the current financial agreements, the government set 12.6 billion euros aside for shoring up the flood defenses until 2050. The Ministry now thinks it will cost between 15.7 billion and 32.9 billion euros, depending on construction costs, inflation, and scarce labor.

The extra work was identified thanks to improved measuring methods and more information about how the climate will develop in the coming decades. The KNMI expects more drought, more heavy downpours, and a sea level rise of between 1.24 and 2.5 meters by 2100, depending on how much CO2 is emitted in the coming years.

All three those factors pose problems for the Netherlands’ flood defenses. The dikes need water to remain strong. Rising sea levels mean higher surge barriers and dunes are required in order to protect the Netherlands from the water. And more intense downpours mean that river discharges are increasing.

“Our dikes, storm surge barriers, dams, and dunes have traditionally protected the Netherlands against the water. And that is literally of vital importance,” Harbers said. “Living and working safely below seal level cannot be taken for granted, which is why the work on our structures is never finished.”

Without the dikes and dunes, about half of the Netherlands could be flooded. “It is good that we now have a better idea of what reinforcements will be needed in the future to keep the Netherlands as safe as possible,” the outgoing Minister said.