How the Netherlands became the global leader in flood defense

Posted: February 21, 2025

On January 31, 1953, the Dutch meteorological institute issued a weather warning for the coming night. It was a Saturday and water levels were already high due to the spring tide. Now, a storm was surging across the North Sea—and it looked like a bad one.

By midnight, the water was over four meters above sea level and gale-force winds were sending frothy waves crashing into the coast. Water began washing over flood barriers in the country’s southwest. Yet many people still dismissed the threat. As one eyewitness from the coast of Zeeland province would later report: “We were just waiting and watching and talking about what the rising water was doing and about what might happen ... The crazy thing was that there were people who just went home and to bed after a while.”

Before daybreak on Sunday, the first dikes gave way. Within a few hours, 770 square miles of southern Holland were inundated, forcing tens of thousands to flee inland. Many were overtaken by the icy waters as more and more flood walls failed. More than 1,800 people lost their lives.

The storm also devastated other parts of the North Sea, including in England, Belgium and Germany. But it hit hardest in the Netherlands, where it became known as Watersnoodramp, or simply de ramp—the disaster. Some towns saw ten months of daily ebb and tide in their streets before the dikes were finally restored and the water pumped out. Today, the tragedy is still commemorated by an annual ceremony. There is an entire museum dedicated to it.

The flood of 1953 did more than just shape Dutch historical memory, however. It also sparked one of the world’s most ambitious schemes to protect people from the sea—and a national quest to learn to live with the water that endures to this day.

Engineering the sea: The Dutch response to flood risk

Water had been an existential issue for the Netherlands long before 1953. Historical records show more than 100 storm surges since 1200, some of them much more destructive than the Watersnoodramp, and settlers in the region were likely trying to hold back the sea much earlier still.

No wonder: over a quarter of the country is below mean sea level; even more of it during high tides and storms (which are now getting worse thanks to climate change). Then there’s the “backdoor”, as Ferdinand Diermanse, a flood risk expert at Dutch water institute Deltares, describes it: two major rivers, the Rhine and the Meuse, flow in from the southeast to empty into the North Sea.

“If you look at all the water—the sea, the rivers, the lakes—about 60% of our country is prone to flooding. That’s quite a lot,” Diermanse says. And because the country is so low and flat, flood events that elsewhere would be concentrated on a river valley spread much farther much faster. “There’s always been a big focus on trying to prevent that.” 

People woke up to the threat a long time ago and began building dikes to tame the water, with varying success. Local water boards to maintain the necessary infrastructure are among the oldest institutions in the country and were first set up as far back as the Middle Ages. Some coastal levees have been reinforced so often that their cross sections reveal an entire layered history of their own.

The Dutch have also reclaimed land from the sea for centuries, by ringing flat areas below sea level with levees and then pumping them dry, initially using windmills. This practice, known as poldering, is behind the famous saying “God created the earth, but the Dutch made their own country.” (Because maintaining polders required broad social cooperation, it also gave a name to the Dutch brand of consensus-based politics.)

Still, despite all efforts to keep it out, the water always came. In 1916, yet another storm killed dozens and helped galvanize the damming of the Zuiderzee, a large and shallow inlet of the North Sea that would eventually be turned into a freshwater lake.

But nothing focused the national effort to build seawalls like the flood of 1953.“It was a defining moment in history,” says Diermanse. “As so often happens, a big disaster helps increase support to do something about it.” 

Building the Delta Works: Turning the tide against future floods

Within a few weeks of the 1953 flood, the Dutch government convened a committee that would eventually set to work on a generational project: the Delta Works, a sprawling network of storm surge barriers, dams, dikes, sluices, locks and levees to fortify the entire southwest Netherlands.

Over the next four decades, Dutch engineers sealed off estuaries, pioneered new moveable flood defenses and reshaped the country itself, transforming a jagged coast stretching some 700 km into a straight 80-km line of defense against the North Sea. The anti-flood system they built is on a scale unmatched anywhere else in the world.

Six years after the disaster, as the works were already underway, a news report illustrated for Dutch viewers where the barriers would close waterways threatening the hinterland. With memories of the devastation still fresh in the nation’s memory, the newscaster sought to soothe concerns that the disaster could ever reoccur: “When these closures and the additional works are completed, the residents behind the high dikes will likely be safe from the violence of the sea."

The most expansive part of the project was the Oosterscheldekering, a series of concrete-and-steel dams and artificial islands stretching nine kilometers across the Eastern Scheldt, a former estuary in Zeeland. It is designed to withstand storm surges that statistically occur only once every 4,000 years and has been referred to as the eighth wonder of the world. On its opening day, in October 1986, Queen Beatrix declared: “The flood barrier is closed. The Delta Works are completed. Zeeland is safe.” 

In fact, the final stage of the works wasn’t wrapped until 1997, with the completion of the Maeslantkering, a giant sea gate guarding the port of Rotterdam—the largest port in Europe and still a crucial hub for industries from oil to steel to agriculture.

The gate’s two curved arms, which normally rest on either side of the canal leading to the city, are each as tall and twice as heavy as the Eiffel Tower. When needed, they swing out into the water to lock together and sink to the bottom, forming a 22-meter-high wall against the sea. The barrier is one of the largest moving structures on Earth; its two ball-and-socket joints, anchored in the embankment on either side of the canal, weigh 680 tons each.

Since the Dutch can afford to leave little room for error when it comes to flood protection, the barrier closes fully automatically before disaster can even strike—for example, when the sea is predicted to rise to more than three meters above sea level near Rotterdam. Still, a team from Rijkswaterstaat, the government department responsible for flood management, is always keeping watch just in case.

In total, the Delta Works cost some $7 billion and took 43 years to complete. The monumental project had one simple goal: to keep out the sea as much as possible. “After the ’53 floods, it was like, ‘Okay, we're going to close several estuaries off,’” Diermanse says.

The country has set itself a high standard: its goal is to reduce the chance of death from flooding for every citizen to at most 1 in 100,000 per year. That requires a fundamentally different approach to many other places around the world, Diermanse says.

“If I compare it to Australia, and maybe other countries as well, there's much more of an acceptance [there] that flooding is part of life, and there's much more focus on reducing damages and casualties if a flood occurs,” he says. “Whereas, in the Netherlands, it's really been the primary focus to try to prevent those floods from happening in the first place. Reducing flood impacts is also part of the strategy, but often seen as complementary.”

The result of that spirit is evident across the country. Today, the Netherlands is home to some 3,600 kilometers of flood defenses, testament to the Herculean effort required to keep the North Sea at bay. Sooner or later, all those defenses will likely need upgrading to withstand rising sea levels and more extreme storms.

But even before the last concrete for the Delta Works had been poured, the Dutch were forced to reckon with the limits of their approach. As they found out, it wasn’t enough to just keep out the water; eventually they would have to learn to live with it, too.