Reuters

Once the city recovers, it will have to decide what to do about the next storm.

As recovery from Hurricane Sandy gets underway, The New York Times has teed up the all-important question of what can be done to prevent similar floods in the future. Governor Andrew Cuomo is already saying the city should consider better flood protections. The Times reports that such a system could cost up to $10 billion, but with Sandy expected to cause several times that in damage, and with sea levels certain to rise, the city may have no other choice.

Even before Sandy hit, critics warned that New York’s flood protection plan was inadequate. Back in September, an engineer at Stony Brook’s Storm Surge Research Group told the Times the city "lacked a sense of urgency" about the situation. The city countered that its size and population makes a "resilience strategy" — stressing recovery rather than prevention — more realistic.

That’s not to say the city has failed to consider flood prevention strategies. Recent long-term proposals range from a relatively simple expansion of wetlands around the city’s coastal edges, to the more considerable construction of sea gates that could block out a storm surge, to elaborate designs for movable barriers that would prevent tidal floods from reaching Manhattan. Immediate measures include better pump equipment and floodgates for the city’s subway system and underground infrastructure.

But the situation will only get worse. By the end of this century, experts believe a third of the city’s streets will be at risk for flooding, up from just 11 percent today. New York recently placed 17th on a recent list of 20 cities most vulnerable to coastal flooding in the coming decades. Rainfall is expected to increase even as the amount of time between major storm surges is expected to decrease:

With that in mind, it's time to shift from consideration to implementation. The 2011 report that predicted a storm like Sandy offered strategies for adapting to a future in which flooding becomes more common. (“If existing infrastructure is not upgraded and adapted to the new demands posed by climate change … it will put the neglected regions, their economies, and, in the worst cases, lives in jeopardy,” the report said.) The report called out two European models in particular as "well-planned, flexible, and foresighted projects": the Delta Waterworks system in the Netherlands, and the Thames Estuary Project in London.

The Delta Works are a series of dams, levees, and surge barriers implemented (over many decades) after a major flood back in 1953. Reporter John McQuaid, who examined the Dutch flood-control system in the aftermath of Hurricane Katrina, writes at Forbes that similar protections make sense for New York. Not only is that system designed to withstand a 1-in-10,000 year flood, writes McQuaid, but mandatory reviews and upgrades ensure that "the level of protection stays the same as the threat evolves."

The Thames Estuary Project was established in 2002 as London’s long-term flood management plan after six years of study. The project incorporates and enhances the massive Thames Barrier, a series of movable gates that span the river, which became operational back in 1982. The barrier has closed as a preventive measure more than a hundred times since its completion, but experts now believe it requires modifications to protect against rising sea levels.

Finding a cost-effective approach to disaster prevention is no easy task, and Governor Cuomo, as well as Mayor Bloomberg and other public officials, have a hard job ahead of them. At the same time, they will never have more popular backing for a prevention plan than right now. Recovery from Sandy should and will come first. The moment that’s done isn’t a moment too soon to start preparing for the next one.

Chart from a 2011 synthesis report on climate change in New York state.

Top image: Joseph Leader, vice president and chief maintenance officer of New York City Transit and Metropolitan Transit Authority (MTA), stands in a flooded stairwell which leads down to a platform at the flooded South Ferry-Whitehall Subway Terminal. (Mike Segar/Reuters)

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