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Big U: New York's Solution to the Sea Level Rise
New York will break ground on “the Big U”, a series of barriers to protect Manhattan from sea-level rise and violent storms.
Jeff Goodell, Can New York Be Saved in the Era of Global Warming? Rolling Stone, July 5, 2016.
Souce:
Almost every coastal city in the world is vulnerable to sea-level rise, but nowhere is there more at stake than in New York. In purely economic terms, the New York metropolitan area is responsible for almost 10 percent of the U.S. gross domestic product and is the largest financial hub in the world.
In a world of rapidly rising seas, New York is better prepared than many coastal cities. As anyone who has seen the rock outcroppings in Central Park knows, much of Manhattan is built on 500-million-year-old schist, which is impervious to saltwater. There is plenty of high ground, not just in Upper Manhattan, in Washington Heights, but also along a ridge that runs diagonally through Queens and Brooklyn. Finally, the city has brains and money and attitude – New York is not going to go down without a fight.
But in other ways, New York is surprisingly vulnerable. First, it's on an estuary. The Hudson River, which runs along the West Side of the city, needs an exit. So, unlike a harbor city such as Copenhagen, you can't just wall off the city from the rising ocean. Second, there are a lot of low areas in Brooklyn, Queens and, most important, Lower Manhattan, which has been enlarged by landfill over the years. If you compare the map of damage from Sandy in 2012 with a map of Manhattan in 1650, you'll see they match pretty well – almost all the flooding occurred in landfill areas. The amount of real estate at risk in New York is mind-boggling: 71,500 buildings worth more than $100 billion stand in high-risk flood zones today, with thousands more buildings at risk with each foot of sea-level rise. In addition, New York has a lot of industrial waterfront, where toxic materials and poor communities live in close proximity, as well as a huge amount of underground infrastructure – subways, tunnels, electrical systems. And because of changes in ocean dynamics, as well as the fact that the ground beneath the city is sinking as the continent recovers from the last ice age, seas are now rising about 50 percent faster in the New York area than the global average.
Hurricane Sandy, which hit New York in October 2012, flooding more than 88,000 buildings in the city and killing 44 people, was a transformative event. It did not just reveal how vulnerable New York is to a powerful storm, but it also gave a preview of what the city faces over the next century, when sea levels are projected to rise five, six, seven feet or more, causing Sandy-like flooding (or much worse) to occur with increasing frequency. It fundamentally calls into question New York's existence.
By 2030 or so, the water in New York Harbor could be a foot higher than it is today. Even with a foot or two of sea-level rise, streets will become impassable at high tide, snarling traffic. Then the big storm will come, as it always does. But if you add a foot or two of sea-level rise to a 14-foot storm tide, you have serious trouble. Water will flow over the aging sea walls at Battery Park and onto the West Side, pouring into the streets, into basements, into cars, into electrical circuits, finding its way into the subway tunnels.
In the aftermath, it's not hard to imagine how this will play out: Businesses that don't need to be in Lower Manhattan will move to Midtown, others to Westchester County or the New Jersey suburbs. The economic engine of the city will sputter. Rents and property values will fall, eviscerating the tax base. Throughout the city, people with money will begin moving to higher ground, leaving the poor behind in polluted swamps of abandoned buildings along the waterfront.
To protect against storms like Hurricane Sandy, the city will break ground on what’s called the East Side Coastal Resiliency Project, an undulating 10-foot-high steel-and-concrete-reinforced berm that will run about two miles along the riverfront. It's the first part of a bigger barrier system, known informally as "the Big U," that someday may loop around the entire bottom of Manhattan, from 42nd Street on the East Side to 57th Street on the West Side.
Big U was one of the winning proposals in Rebuild by Design sponsored by the U.S. Department of Housing and Urban Development. It's the love child of a collaboration headed by the Bjarke Ingels Group, the hot Danish firm that has designed a number of playful buildings around the globe. As far as walls go, the Big U is designed to be a nice one,a wall with benefits.
The barrier will be covered with grass and trees in many places, as well as benches and bike paths – it's the East Side equivalent of the High Line, the hugely popular elevated train track on the West Side that has been transformed into an urban park.
source: http://archinect.com/news/article/101030520/a-closer-look-into-the-big-u-big-s-winning-proposal-for-rebuild-by-design
There are plans in the works to build other walls and barriers in the Rockaways and on Staten Island, as well as in Hoboken, New Jersey, across the Hudson River. But this project in Lower Manhattan is the headliner, not just because the city may spend $3 billion or more to construct it, but also because Lower Manhattan is some of the most valuable real estate on the planet.
Building walls around a city is an idea that is as old as cities themselves. In the Middle Ages, walls were built to keep out invading armies. Now they are built to keep out Mother Nature.
Obviously, if they are built right, they work. More than a quarter of the Netherlands is below sea level; without walls, dikes and levees, much of the nation would be a kingdom of fish. New Orleans exists today only because of its enormous levees. Virtually every coastal city in the world is defended by sea walls of one kind or another.We can't keep building walls forever. Sometimes they are necessary, but we also realize that we have to learn to live with the water. If it is not built right, a wall can create as many problems as it solves."
For one thing, there's always a question about what level of protection the barrier is designed to provide. In parts of the Netherlands, barriers are required to protect from a one-in-10,000-year flood; in New York, most government agencies require protection only for a one-in-100-year flood plus 30 inches of sea-level rise. A barrier like the Big U would in theory be designed to protect from another Sandy, but not much more.
Another obvious problem is that barriers only protect the people who are behind them. The first stage of the Big U is clearly about protecting the Wall Street. But how long will it be before Red Hook, an economically diverse neighborhood in Brooklyn that was also heavily damaged by Sandy, gets a barrier? Worse, a wall around Lower Manhattan might actually deflect more water into Red Hook. "It might keep water out of Manhattan, but it could make the problem worse for people in Brooklyn, not better."
The most pernicious problem might be complacency. Barriers, dikes and levees make people feel safe, even when they are not. As sea levels rise in the next century, even a $3 billion wall won’t keep Lower Manhattan above water.
Other planners are skeptical and suggest solutions like elevating the coastline or creating a series of islands to act as a natural barrier. Perhaps the boldest idea for how to protect New York was called the Blue Dunes, a 40-mile-long chain of islands that a group of scientists and architects proposed building in the shallow water about 10 miles off the coast of New York. From the city, they would have been invisible, but together they would have formed a protective necklace of sand running from New Jersey to Long Island. the Blue Dunes were a brave and innovative proposal to absorb the wave energy of the Atlantic Ocean before it hit the city, lower the impact of high tides and buy the city time to recalibrate for sea-level rise. The idea, proposed by a group headed by Dutch landscape architect Adriaan Geuze as part of the Rebuild by Design competition, would have been controversial, expensive and disruptive to anyone with a sentimental attachment to a "natural" coastline.
In the end, there is only one real solution for sea-level rise: moving to higher ground. The logic is simple: In the long run, it's cheaper simply to buy people out of their homes than to keep paying for them to be rebuilt after storms (it also moves people out of harm's way).
For New York, this is just the beginning of the story. The city is going to be dealing with rising seas for decades, even centuries. If it's going to survive, fortifying New York will require more than just walls – it will require a radical rethinking of the relationship between the city and the people who live in it. New York has always defined our idea of what a city is and can be," Now, New York may well define our idea of urban survival in a future of rapidly rising seas.