Maeslantkering

For centuries the Netherlands has waged a constant battle with water, fighting to protect low-lying land from storm-driven sea water and rain-swollen rivers. Much of the nation sits below sea level, and two-thirds of its population lives on land that would flood regularly if not for a complex system of dikes and surge barriers.

So it’s no surprise that the Dutch are world leaders in flood protection, pioneering movable storm surge barriers and other water management technologies that are emulated around the world. The Netherlands is also innovating in climate change-related flood planning, such as creating space for rivers to overflow and constructing parking garages that can serve as emergency reservoirs in flood-prone cities like Rotterdam.

Rijkswaterstaat

One dramatic example of Dutch flood control ingenuity can be found near Hoek van Holland, at the mouth of the New Waterway channel that connects Rotterdam’s busy port to the North Sea. The Maeslantkering is the world’s largest movable storm surge barrier, consisting of two massive steel arms, one positioned on each side of the channel, that can lock together in the middle of the waterway and block a storm tide of up to five meters.

The enormous white structure – consisting of lattice-like tubes and almost as long as the Eiffel Tower in its entirety – defends Rotterdam, the country’s second-largest city, and its vital port. Rotterdam’s port is Europe’s largest, handling more than 140,000 ships annually, and an economic engine that directly employs 90,000 workers. Transportation companies and other port-related businesses employ tens of thousands of additional workers.

The Maeslantkering was completed in 1997 and has been used only twice to block a storm surge, in November 2007 and again in January 2018. The Maeslantkering is the final piece of the Delta Works, a construction program started by the Dutch government after the catastrophic floods of 1953, when a surge blown from the North Sea rushed through the estuaries of Zeeland, North Brabant and South Holland killing more than 1,800 people. 

The series of dams and movable barriers, which stretch along the southern Dutch coastline, was designed to resist a storm so severe that, according to computer projections, it could happen only once every 100,000 years.

“After the big flood of 1953, the Dutch people said this can never happen again,” says Jeroen Kramer, a press officer at the Keringhuis, an information center located next to the Maeslantkering. Delegations from coastal cities around the world visit the Keringhuis, along with other water control innovations around Rotterdam, seeking ideas they can use back home.  

“Our goal for the future is that only one person will die every 100,000 years because of a flood, and that’s unbelievably high,” says Kramer. “I always say we have a big advantage in the Netherlands. We started centuries ago [with guarding against floods], so we have more knowledge at this time. That’s why we have to make sure this knowledge goes to all countries.”

On a recent visit, Kramer took me on a tour of the Maeslantkering and explained how it works. Here are some of the highlights:

*It takes two hours to fully close the Maeslantkering barrier – half an hour for the two arms to float out to the middle of the New Waterway, and 90 minutes for the gate to sink to the bottom.

*It also takes a couple of hours to open the Maeslantkering. “There’s a lot of pressure to open the barrier as soon as possible after a storm passes … it costs a lot of money when the shipping lane is closed and ships are waiting.” Each day about 300 ships pass through the New Waterway on their way to the Rotterdam Port or toward the North Sea.

*The Maeslantkering is controlled by computers that use a closed-circuit system to prevent hacking. The computer system monitors sea levels every 10 minutes during the storm season, and it’s programmed to shut the gate when water levels reach three meters. “That’s when the computer says now we have to close because it’s getting dangerous.” Storms that head toward Rotterdam from the northwest put the system on high alert. “Because of where we’re positioned in relation to the English Channel, all the water is pushed to this narrow spot off the Dutch coast.”

*When the gate is signaled to close, the two arms float toward the middle of the New Waterway, where they meet. The hollow tubes and walls that comprise the arms then fill with water and sink into the channel’s bed, forming a 22 meter-high wall. Pressure from the storm surge is transferred to ball joints located on either side of the channel. “The whole construction is like a big human arm, and the ball joint is like a shoulder. These are the largest ball joints in the world, each is 10 meters wide. You will notice that the steel arms are all interlocking triangles, which are the strongest design and can handle the most force.”

*When it’s time for the Maeslantkering to be re-opened, the computer signals 30 pumps inside the gate to push water out of the steel tubes. “The 30 pumps can pump out the water in 90 minutes. Then the walls come up again and we can sail the arms back to the open position.”

*The New Waterway is 17 meters deep, and the Maeslantkering wall is 22 meters high. “That means we can handle five meters of extra water … the 1953 storm measured 3.85 meters at Hoek van Holland. So we could block a tidal surge that’s a meter higher than the 1953 level … we’re in good shape even with rising sea levels and climate change. The height of the wall is high enough to hold back the water.”

*When the Maeslantkering opened in 1997, it was the first storm surge barrier of its kind. Since then, the idea of using two movable arms to guard busy shipping lanes against storm surges has been emulated by other cities around the world, including St. Petersburg and New Orleans. 

*The Maeslantkering closed for just the second time in its 21-year history in January 2018, when it closed for five hours. “We did this because we wanted to test the barrier during an actual storm. The water didn’t come higher than 2.72 meters during the January storm, but the computer was programmed to close the gate when the water level reached 2.6 meters rather than three meters.” The barrier is tested annually in September when the weather is usually calm. “It was a real storm test for us. The government has mandated that we need to do this kind of test every seven years.”

*”Everything about the Maeslantkering is Dutch. The design and engineering. Even the materials, except for one part of the ball joint which comes from the Czech Republic.” In typical Dutch fashion, no single architect or engineering firm is named as heading the project; rather, the credit is shared by all who were involved in its design and construction.

Kramer, a gregarious guide, was born and raised in Hoek van Holland. “I was born in an area where there are big storms and winds every year. So I have a strong feeling about everything we do here because I know what can happen.” 

Kramer looks forward to a storm that puts the Maeslantkering and other Delta Works systems to a real test. “The only reason I hope for a storm like that is I know we are safe. When I was young I wasn’t very happy when a big storm was coming in. But with these barriers now, it’s safe.”