New York labours to raise flood defences a decade after Hurricane Sandy

In April, authorities in Battery Park City, a neighbourhood on Manhattan’s south-west tip, began painting sections of the lamp posts along the waterfront light blue. This was not a matter of decor. Rather, it was an attempt by local authorities to impress upon residents just how high the tide may climb in future storms. From lamp post to lamp post, the light blue portions ranged from 9-13 feet above an esplanade that is, itself, 10 feet above sea level.

© Battery Park City Authority

“Standing next to these poles and looking at them really strikes a chord,” said BJ Jones, the president of the Battery Park City Association, which oversees the neighbourhood. “It’s a good visual besides looking at maps of flood plain elevation.”

Saturday marks 10 years since Hurricane Sandy made landfall in New York City, killing 43 residents, causing $19bn in damage — much of it from flooding — and awakening residents to a vulnerability many had not previously appreciated. As that anniversary approaches, the city’s efforts to improve defences in low-lying neighbourhoods such as Battery Park City are at last becoming visible, even if they are still far from complete.

Building codes have been tightened. More than $11bn in federal funds have been spent to repair properties and infrastructure, and in many cases reinforce them to better withstand future floods. Perhaps most dramatically, workers have at last broken ground on the first of a ring of new defences that will, perhaps by 2030, gird lower Manhattan.

“New York is much better protected than it was a decade ago — and it’s also still nowhere near where it needs to be,” is how Rohit Aggarwala, New York City’s chief climate officer, assessed the situation.

NYPD officers stand guard next to barriers used to prevent flooding at the South Street Seaport as New York City braced for tropical storm Isaias in August 2020
NYPD officers stand guard next to barriers used to prevent flooding at the South Street Seaport as New York City braced for tropical storm Isaias in August 2020 © Eduardo Munoz Alvarez/Corbis/Getty Images

Certainly, New Yorkers’ mentality has changed. Prior to Sandy, Aggarwala was working on sustainability issues for Mayor Michael Bloomberg when he encountered a real estate lobbyist who rejected the suggestion that buildings’ mechanical systems might be removed from basements and placed on higher floors so they would be less vulnerable to floods.

“‘That’s the craziest thing I’ve ever heard. There’s rentable space on the second floor!’” Aggarwala recalled the lobbyist complaining.

The idea seemed less crazy after 2mn residents lost power due to Sandy, in some cases for weeks. At Bellevue Hospital, hundreds of patients had to be evacuated after the failure of back-up power systems whose critical components were located in the basement and swamped by the East River.

New York began studying the lessons of Sandy almost immediately, and then drafting a series of plans — and then revised plans — to adapt for the future. The objective, according to Aggarwala, is not to prevent all flooding but to try to ensure that critical systems can return to service within hours — not days — if water rushes in.

After 400 years of a relatively mild climate, the city is not only facing the growing risk of coastal flooding but also extreme heat and interior flooding from larger storms that drop more rain.

“Every time we plant a tree or repave a sidewalk or build a road” it should in some way be regarded as a climate resiliency project, Shaun Donovan, who led the Obama administration’s Hurricane Sandy Task Force, said at an event this week to commemorate the 10-year anniversary.

So far, the effort has been “plodding”, according to a report released earlier this month by New York City’s comptroller. It also warned that the city faced mounting danger as ever more of its property fell into an expanding flood zone. By 2050, that will encompass more than a quarter of its public housing.

That assessment may change now that work has begun in earnest on a U-shaped barrier of defences to protect lower Manhattan from rising sea levels. Engineers have broken ground on a section that will protect the east side, below 25th Street, and will do so any day now on a companion that will hug Battery Park City on the south-west edge of the island.

The objective is to prepare for what city forecasters predict a 100-year storm might bring in the year 2050, by which time sea levels are expected to be 2.5 feet higher than they are today. To achieve that, engineers have planned a series of hidden — and not-so-hidden — interventions along the Battery Park esplanade.

In some places, they will take the shape of a physical wall or retractable floodgate. In others, it is the introduction of undulating berms along a cycle route. Then there is Wagner Park, which is particularly low ground. It will be raised 10-feet with extensive use of landfill and clever landscaping. What looks like tiered seating in a public park will, in fact, be a barrier against rising seas.

Construction workers at the site of a flood defence project on the east side of Manhattan
Construction workers at the site of a flood defence project on the east side of Manhattan © Ed Jones/AFP/Getty Images

“You wouldn’t really know walking by it that it’s a flood resiliency component,” said Gwen Dawson, who oversees planning and design for the Battery Park City Authority.

Battery Park City was, itself, once water. The residential development was created in the 1970s on land reclaimed from the Hudson River with millions of cubic feet of soil excavated from the base of the nearby World Trade Center. Developers incorporated a small seawall, but nothing of the magnitude necessary to deal with coming storms.

“There was not any serious consideration of sea level rise or the impact of climate change,” said Dawson. “What we found out in Sandy is that we were very close to having much worse outcomes.”

It was always going to take time to devise a coherent system, say city officials, while adhering to the constraints of federal contracting laws. Another drag on the process has been the difficulty of winning public approval to alter public spaces — even in a city where residents overwhelmingly accept the threat posed by climate change.

“It was: ‘Oh, you’re ruining our park.’ No, we’re saving it,’” Gernot Wagner, a Columbia University economist who serves on the city’s panel on climate change, said, recalling the civic battles that erupted over plans to fortify the east side.

At the local level, where so many decisions are made, too many incentives point in the wrong direction, Wagner complained. After a disaster, for example, local politicians inevitably vow to rebuild things as they were, and the federal government supplies money to do so.

Still, he seemed more inclined to celebrate than despair as the Sandy anniversary neared. “It took almost a decade,” said Wagner, “but now it’s happening.”

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