A report by the Natural Resources Defense Council puts a number, if not a face, to the idea that federal flood maps in effect when Sandy hit vastly underestimated the extent of likely flooding: 289,719.
That is the number of people who lived in parts of New York City that were inundated by Sandy and yet were not part of the 100-year flood zone, as mapped by the Federal Emergency Management Agency.
By comparison, the environmental group determined that about 206,000 people actually lived inside the boundaries of the 100-year flood zone: a 33-square mile area that includes large parts of some shoreline neighborhoods, such as the Rockaways, the East Shore of Staten Island and Coney Island, Brooklyn.
In other words, Sandy affected more people who lived outside the flood zone than inside it.
“There were tens of thousands of people, hundreds of thousands who were outside the flood zone and yet were hit by floodwaters,” said Kim Knowlton, the report’s co-author and a senior scientist at NRDC.
Bill McDonnell, deputy regional director of mitigation for FEMA, said the agency bases its flood maps on past events, but that municipalities are welcome to impose stricter standards reflecting sea level rise.
In the past, FEMA has said the maps were not intended to predict the extent of flooding by such an extreme storm as Sandy, which is considered by some researchers to be a 700-year storm. The agency has since redrawn even its 100-year flood zone to be far larger than the old one. The new map has not yet been finalized.
The NRDC, in its report, argued that even the proposed flood zone does not go far enough because it does not anticipate the effects of sea level rise.