The Afsluitdijk – one of the low-lying Netherlands' key sea defences – has been taking a battering for 87 years. With climate change bringing more powerful storms and rising sea levels, the dyke is now getting a €547m makeover.

The 32km Afsluitdijk, a narrow strip of man-made land that lies between the shallow Wadden Sea and the Ijsselmeer inland sea, also serves as a motorway linking the provinces of North Holland and Friesland.

Using a 300m wave tank nicknamed "the flume", engineers in the city of Delft – better known for Johannes Vermeer and delicate blue and white pottery – are pounding a scale model of the dyke with waves that should occur only once every 10,000 years, as part of the redesign process.

Boris Teunis, an expert on emergency water management with Dutch water agency Rijkswaterstaat, says there is no time to waste.

"If you look at the sea level rise, it's already going on at a constant base since the beginning of the 21st century, like two millimetres a year. So, that is expected to continue and what we are worrying about is if it will accelerate, the increase of the sea-level rise," he said.

The Dutch government this year established a "knowledge program on rising sea levels" that aims to feed expertise into the ongoing programme of building and maintaining water defences. It has earmarked €18 billion for innovation and maintenance in water defence for the period 2020-2033.

The investment does have some return, however – it is estimated that water sector exports were worth €7.6 billion last year, as the Dutch sell their expertise to other low-lying countries and cities around the world.

Teunis added: "We [Dutch] have the safest delta in the world. What will happen in the future, it's difficult to say. That's what we are currently working on, to get as much knowledge as possible about developments in the future and then take stapes to prepare ourselves for these situations."

Meanwhile, construction work to strengthen the Afsluitdijk has begun. It includes laying thousands of custom-made concrete blocks and raising it in parts, and is expected to continue till 2023.

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