New York City’s flood maps haven’t been updated in 14 years, potentially putting tens of thousands more New Yorkers in harm’s way and leaving them without a means of paying for damage if a storm should hit.
That’s according to researchers at the New School, who tracked new construction and population changes in six flood-prone neighborhoods between 2007 and 2018. Currently, a Federal Emergency Management Agency (FEMA) map last updated in 2007 determines how much of New York City is at risk of flooding—and which homeowners are required to reference by law when purchasing flood insurance.
The study shows that due to a steady stream of building developments, these high-risk flood zones have become denser, putting more people in these budding communities in the path of dangerous and destructive floodwaters than before Superstorm Sandy. Income levels have dropped across some of these neighborhoods, making it harder for them to prepare for future natural disasters.
And the current flood zones in these neighborhoods are potentially 46% larger than they appear on the official maps in circulation, the researchers found.
“Flood risk is much more complex than a hard-drawn line that identifies what is and what isn’t,” said Pablo Herreros-Cantis, a research fellow at the New School’s Urban Systems Lab, who presented the work in June at a climate conference organized by Columbia University’s Earth Institute.
FEMA proposed an updated map for New York City, which found that twice as many buildings as before were at risk of flooding. It was supposed to go into effect in 2015, but the city appealed it, arguing that its flood zones were overestimated and would force homeowners to buy unnecessary or overly expensive insurance. A new floodplain map is due out in 2024, but in the meantime, developers and homeowners are operating off the outdated version. (Developers building in the proposed flood zone do have to include some resiliency measures until a new map is ratified, according to the city.)
To get a clearer picture of the current flood risk, Herreros-Cantis and his team focused on six neighborhoods across the five boroughs: City Island/Co-Op City in the Bronx, Coney Island in Brooklyn, the Lower East Side and East Harlem in Manhattan, the Rockaways in Queens, and Stapleton in Staten Island.
FEMA High-Risk Flood Zones For Coney Island, Official 2007 Map vs. Proposed 2015 Map
All were hit hard by Hurricane Sandy, and all include “potential environmental justice areas”—defined in New York state law as communities with a large proportion of low-income residents or residents of color that may be disproportionately affected by pollution caused by the government. The researchers studied land use and census data in these neighborhoods between 2007 and 2018. They also compared these data between the official and preliminary flood zones.
All the neighborhoods recorded building development in flood zones between 2007 and 2018. In Co-Op City, the number of buildings in the floodplain increased by 17% during this period, while East Harlem also added thousands of residential units in flood-prone areas.
If you build it, they will come, and new residents flocked to these flood zones during the same period. The floodplain populations of Coney Island and the Rockaways increased by 7% and 12%, respectively.
“There’s a lack of a clear understanding about what the flood risk is,” said Herreros-Cantis. “And at the same time, things are happening and development is happening and population growth on the coastline is happening.”
Those changes coincided with other shifts that increased the vulnerability to harm after flooding. Both East Harlem and the Lower East Side became home to a larger share of elderly residents during the period studied. Stapleton saw a 35% spike in households below the poverty line. Poverty also increased in Coney Island and East Harlem.
“How able are you to combat extreme weather events that happen? And prepare for them [and] rebuild after they hit? All of that has to do with income,” said Sonal Jessel, director of policy at WE ACT for Environmental Justice, who wasn’t involved in the study. Past studies show that poor or elderly communities have a harder time fleeing floodwaters, finding a safe place to stay during a disaster and rebuilding in the aftermath.
FEMA’s updated map would add 11% more people to the high-risk flood zones in the New School’s study and expand their land area by 46%. But many of those new additions are wealthier, on average, than the people living in the original floodplain. So the newcomers might have an easier time coping with floods while members of the original community continue to struggle.
Moreover, the 2007 and 2015 maps are based on past storms and assume a stable climate, so they don’t show how risk might increase as the city grapples with the effects of climate change, noted Bernice Rosenzweig, professor of environmental studies at Sarah Lawrence College, who was not involved in the study. The maps also don’t reflect the susceptibility of different neighborhoods to flooding from extreme rainfall, like the kind that deluged roads and subway stations during Tropical Storm Elsa in early July.
We are already at risk from flooding, even in a stable climate.
“We are already at risk from flooding, even in a stable climate,” Rosenzweig said. “It’s a technological and scientific challenge to understand and manage that risk as it is. But that’s going to be greatly exacerbated with climate change.”
Beginning in October, FEMA will calculate threats using a new method called Risk Rating 2.0, which will include heavy rainfall and other sources of flooding not covered by the current maps. And the New York City Panel on Climate Change uses FEMA’s 2015 map as a baseline to predict neighborhoods’ flood risk through the end of the century.
WNYC/Gothamist contacted the mayor’s office for comment, and a spokesperson pointed to a press release from May citing a new set of city rules that restricts the construction of nursing homes in flood-prone areas and allows for more updates that shore up buildings against flooding, like elevating electrical equipment. Jessel says the city should prioritize the most vulnerable flood-prone neighborhoods for such efforts—and soon.
“We’re experiencing the extreme weather events today,” she said. “Massive flooding and rainstorms and massive heat waves. And so the people that are affected first and worst by that should get the investment first when it comes to protection.”
Ultimately, Herreros-Cantis says, drastic action is needed: city officials must accept that “controlling and regulating and even limiting the densification of waterfronts in the city is a climate adaptation measure that is going to be needed at some point.”