NYC Challenges Accuracy of FEMA Flood Maps

City officials announced last Friday they will challenge new FEMA maps that greatly expand flood zones in New York City.

The federal maps, set to go into effect in 2016, would nearly triple the number of properties included in official flood zones, and affect more than 400,000 citizens.

Alternative maps proposed by the de Blasio administration would reduce the number of buildings in the proposed FEMA flood zones by nearly half. This could have a profound impact on the flood insurance burdens faced by residents.

But questions also linger about the wisdom of reducing flood zones in a post-Sandy era—and some climate experts wonder whether the FEMA maps actually go far enough.

Whose Maps are Inaccurate?

FEMA maps with 2010 updates compared to proposed 2016 FEMA maps.

Daily News reports that city officials claim up to 35% of the area FEMA designated as flood-prone is labeled inaccurately. The city argues that federal calculations used a flawed analysis of prior storms, among other reasons.

Many of the homes that would be affected by the new maps are in South Brooklyn (Canarsie), South Queens (Howard Beach, the Rockaways), and Staten Island.

As NYER has reported in the past, these new FEMA maps will have important implications for resiliency projects, human safety, and government policy, but nowhere will the impact be felt more than on individual home flood insurance rates.

Under the proposed FEMA maps, a typical home in the high-risk zones could see premiums increase from around $1,000 in 2014 to nearly $14,500 by 2030.

According to Daily News, the city hired outside engineers to create its own maps. By their estimates, only 230,000 New Yorkers live in flood zones, which include 45,000 buildings. That’s 26,500 fewer buildings than the new FEMA maps count, and 170,000 fewer people.

The review process could take more than a year to complete; no insurance changes will be made during that time.

A Post-Sandy Era

Flooded Battery Park Tunnel after Hurricane Sandy. Photo credit: Timothy Krause/Creative Commons.

While many, including U.S Senator Charles Schumer, applaud the city’s new calculations, there are others who question the wisdom (and safety) of reducing flood zones in a time of changing climate.

Indeed, there are some who wonder if FEMA’s maps actually went far enough. The Natural Resources Defense Council claims that FEMA’s maps are based on outdated data that does not take into account future effects of climate change, including sea level rise that has occurred just in the last 10 years.

In addition, NRDC found FEMA’s computer models were not calibrated against data from Hurricane Sandy. As a result “the new 100-year flood zone mapped by FEMA is significantly smaller than the area at risk of flooding assuming 3 feet of sea level rise or the surge from a Category 3 hurricane.” By comparison, Sandy was barely a Category 1 storm.

NYER will be covering additional reactions to New York City’s challenge to the FEMA maps in coming days. Stay tuned.


The City’s Flood Zones Have Expanded: Are You In One?

The number of New Yorkers living in flood zones is about to almost double. Now more than ever, it makes sense to check if you live in a flood zone.

Over 400,000 New York City residents, an increase of 84% from the current 218,088, will soon be living in flood zones.

As we reported last Fall, the Federal Emergency Management Agency has updated maps that depict which parts of New York City are at risk from a 100-year-flood—meaning areas that have a one percent chance of flooding each year.

Finalized maps will be released next year.

Properties included in the expanded flood zones have jumped from 23,885 structures in 2010 to 84,596 in 2013—an increase of more than 60,000 buildings.

The number of buildings in flood zones more than doubled in all boroughs except the Bronx, but the largest spike came in Brooklyn: more than 42,000 structures are now identified as at-risk, compared to the previous 5,648.

If you own a home or residential building in a flood zone, you will be required to purchase flood insurance. Flood insurance premiums are projected to increase significantly, a problem which the City has been trying to address.

Check out our latest story, written by contributor Samar Khurshid, to learn more about rising flood insurance rates and what they mean for New York City.

Find out even more about New York City’s flood insurance issues here.

See the latest sea level rise projections for New York City here.