New York sea defences boosted by Dutch expertise

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Disastrous flooding in New York? Scientists from Amsterdam’s VU University are helping the US metropolis – built for the most part on islands – to withstand rising sea levels. But they’ve swapped their Dutch know-it-all manner for “a bit of humility”.

The first presentation of the Dutch plan for New York ended abruptly. “We were perhaps a bit too know-it-all, telling them what they should do, like construct really high dykes,” explains Jeroen Aerts, the VU’s professor of climate and water risk. “We were back on the street in no time, because it was all too dear and New York isn’t the Netherlands. Then, we went away to learn how they make plans and implement measures here.”

That was five years ago. The VU’s Institute for Environmental Studies has in the meantime become involved in the plans to make New York’s more than 800 kilometres of coastline ‘climate-proof’. While they were in New York for interim meetings, Professor Aerts and his colleague, Wouter Botzen, talked about last September’s Hurricane Irene.

The threat of flooding was serious enough that Mayor Michael Bloomberg ordered the evacuation of hundreds of thousands of people from low-lying neighbourhoods. In the end, the Big Apple wasn’t hit by major flooding. In the future though, higher water levels combined with more severe hurricanes could mean that storm surges are catastrophic.

Wall Street
“Then, people could be killed,” explains oceanographer Malcolm Bowman. “Then, the water will be sloshing down Wall Street. Important infrastructure will be hit: hospitals, sewers, communication lines.”

Professor Bowman was responsible for the New York planners and the Dutch VU scientists first getting together. “Bowman was really interested in the Dutch approach,” explains Professor Aerts. “Our dykes and storm surge barriers.”


Flood insurance
The Dutch team went to work on the plans and ideas New York already had. Advising, rather than telling people what they should be doing? “Yes, with a bit more humility,” laughs Professor Aerts. “And, I’d like to stress that we can learn a thing or two from the Americans. They’re much keener on coping for yourself, your own responsibility - flood insurance, for instance. We don’t have that in the Netherlands. That’s something we can take onboard.”

Flood insurance is an important part of the VU plan for New York. “There are two ways to motivate people to take measures,” says Dr Botzen.

“You can impose all kinds of tough construction regulations. But, you can also give people positive incentives – for example, by offering reductions on insurance premiums. That’s how you guide them into building less in risk areas.”

Green roofs
Higher dykes and storm surge barriers are still options in the Dutch plan, but for the time being they’re not pushing them so much. The VU scientists are putting forward environmental measures such as the extension of the salt marshes at Jamaica Bay near Kennedy Airport. These would serve as buffer zones to absorb the waves produced by higher seas. “A small-scale measure, such as green roofs on skyscrapers, would absorb rain water for a time, only later releasing it into the sewers,” says Professor Aerts.

New York is earmarking hundreds of millions of dollars to develop and protect its coastline. The Dutch advice on how to deal with climate change has been integrated into the city’s long-term plans. However, American politicians seem to be particularly difficult when it comes to the notion of climate change. Isn’t that a problem? Professor Aerts:

“Even if you don’t believe in climate change, New York will still have to take measures. Over the next 30 years, New York will get a million or so new residents. Most of them will go to live in flood-risk areas, because there’s space there and it’s beautiful. You have to consider long-term anti-flooding measures for that reason alone, because far more people will be living close to the water.”