When Jeroen Aerts, a Dutchman tasked with crafting a plan to defend New York City from flooding, first looked at its coastline seven years ago, he was taken aback by how vulnerable it was.
Unlike some of the other large cities around the world, such as London and Amsterdam, that have comprehensive flood defense systems with levees and storm surge barriers, New York was completely at the mercy of the elements.
I was looking at the water and wondering - where are the levees? said Aerts, a professor of environmental risk management at the VU University in Amsterdam and an adviser to New York City. Nobody was doing anything on flood risk.
As the devastation after super storm Sandy this week made all too clear, little progress has been made since Aerts first looked at the Atlantic Ocean from New York's shores. The storm caused widespread flooding, power outages, travel chaos and left more than 40 people dead in New York City. Early estimates predict it also caused up to $18 billion in economic losses in New York state alone.
New York state and city officials have started talking about the need for a comprehensive flood defense system, but many obstacles remain. According to Aerts' top estimate, it could cost as much as $29 billion to build and implement. The question of who will pay for it remains unresolved.
Most comprehensive proposals for storm surge defenses involve a system of two to four barriers, each spanning from a third of a mile (.5 km) to six miles (9.6 km) and towering about 30 feet (9 metres) above sea level. This is to be supplemented by levees, dikes, bulkheads and beach strengthening.
One of the most prominent plans calls for a 0.84-mile East River storm surge barrier from Whitestone in Queens to Throgs Neck Bridge in the Bronx, and a much longer 5.92-mile Outer Harbor barrier linking Sandy Hook in New Jersey to the Rockaway Peninsula in Long Island.
Aerts estimates storm surge barriers could cost between $10 billion to $17 billion, while additional defenses such as levees and adding sand