This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
As New York, New Jersey and the rest of the northeastern U.S. come to grips with Hurricane Sandy's impact, some leaders there are realizing that two debilitating hurricanes in as many years there are a sign that infrastructure there needs rethought, not just rebuilt.
Postmortem assessments of Sandy's impact should include a "fundamental rethinking of our built environment," New York Governor Andrew Cuomo said Wednesday during a press conference. "The challenge is not just to build back but to build back better than before."
Cuomo called the storm, which has claimed more than 30 lives so far, "frightening" and described scenes around the city that sounded like something out of Michael Bay movie—including lower Manhattan's Ground Zero site flooding and sections of the nearby West Side Highway submerged beneath more than 1.5 meters of water. Overflow from the Hudson River also covered tracks and lapped at the platform along an eight-kilometer stretch of a Path Train tunnel connecting lower Manhattan with New Jersey, the governor added.
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The city's subway tunnels and underground infrastructure are normally an asset for moving millions of commuters and residents around on a daily basis. During a storm of Sandy's magnitude—"when the Hudson River was intent on meeting the East River," Cuomo noted—they become a liability, particularly because the subways share space underground with much of the city's electrical infrastructure.
Getting water out of these tunnels is one of the main orders of business, Cuomo said. Sandy flooded seven subway tunnels, three of which had been pumped clear as of the press conference.
Water removal is perhaps the biggest challenge that hurricanes create, agrees Phil Bedient, a Rice University professor of civil and environmental engineering. New York City will have to pump out tunnels and basements and run that water into the storm sewer system. "You'll see big pipes, one foot in diameter, all throughout downtown New York as they do this work," he says. This storm sewer system flows out to the surrounding rivers, which have subsided by now.
New York City and the surrounding coastal areas present several challenges for storm protection and recovery, in particular the combination of its aging, subterranean infrastructure, high-rise buildings and dense population—all in very close proximity to the water, Bedient says.
"What's going to be unique about the East Coast's [recovery] is so much of the infrastructure there is very old," Bedient says. "The tunnels and anything to do with the infrastructure below ground is probably going to be more difficult to deal with compared with some of the more modern infrastructure that exists on the Gulf Coast."
Sandy will probably not end up being as devastating as Andrew, Katrina or Ike, but it was a lot worse than most people in the Northeast were expecting, Bedient says. Whereas New York City and the surrounding area experienced four-meter surges at Sandy's worst, Katrina and Ike hit the Gulf Coast with 8.5-meter and five-meter surges, respectively, he adds.
Bedient suggests that a three-meter-high dike around Battery Park near Ground Zero could provide some measure of protection for lower Manhattan. "It wouldn't be that hard to do, and it's worked for areas like Lake Pontchartrain in New Orleans," he says, adding that the city must weigh the cost of such a levee against, for example, the cost of Wall Street shutting down whenever a comparable storm hits. "You have to begin to think more carefully about long-term protection especially with back-to-back hits."
During his press conference, Cuomo noted that other parts of the country have designed their infrastructure to account for coastal storm flooding. "Part of this is the recognition that climate change is a reality, and it's a reality that we're vulnerable," he added. "Protecting this state from coastal flooding is a massive, massive undertaking but a conversation that is overdue and a conversation that should begin."
Image of lower Manhattan courtesy of Nosha, via Flickr.