Nearly 85,000 buildings in New York City are officially in a flood zone, according to a report released by the City Comptroller Scott Stringer last Wednesday, on the two-year anniversary of Hurricane Sandy. Almost half of those structures are in Brooklyn.

More than 400,000 people live in these zones, and Stringer’s report estimates that the property value at risk is upwards of $129 billion.

Moving the Frontline

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

The report, “ON THE FRONTLINES,” analyzed updated maps from the Federal Emergency Management Agency 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.

FEMA’s flood maps for New York City have not been re-issued in any meaningful way since they were created in 1983. Small expansions or updates are occasionally released; Stringer’s report compares a 2010 update with overhauled versions proposed at the end of 2013. Those maps should take effect in 2016.

According to Stringer’s analysis, “FEMA’s revised maps depict a greatly expanded floodplain that places almost three and a half times as many structures in high-risk zones and anticipates greater severity of flooding for those buildings already in the flood zone.”

Properties included in the expanded flood zones 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.

The value of properties located within flood zones has also increased accordingly. The Comptroller’s Office estimates that $129,139,514,673 worth of structures are now at risk — an increase of more than 120 percent over previous maps.

In Manhattan and Staten Island, the value more than doubles. In Brooklyn, it triples.

Maps with Consequences

Storm damage from Hurricane Sandy. Photo credit: Pamela Andrade via Creative Commons.

The new FEMA flood zones 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.

The National Flood Insurance Program uses floodplain maps to determine insurance rates for homeowners.

The expansion of the flood zone means that mandatory insurance rates could spike for thousands of New Yorkers by as much as 18 percent.

Researchers identified 28,000 homes that within the zones that could see insurance rates soar from $400 to between $5,000 and $10,000 for the same amount of coverage.

These dramatic increases pose an enormous hardship to thousands of New Yorkers. According to a study conducted by the Center for New York City Neighborhoods, more than 30 percent of homeowners in the floodplain earn less than 60 percent of the New York City Area Median Income.

FEMA Maps Fall Short

Despite the expanded coverage of FEMA’s new maps, some critics say they actually don’t go far enough.

In April, Natural Resources Defense Council released a report stating that the new FEMA maps are already based on outdated data that does not take into account future effects of climate change, including sea level rise that has occurred in the last 10 years.

In the summer of 2012, Congress passed the Biggert-Waters Flood Insurance Reform Act, which requires FEMA to update maps while taking into account the “best available science regarding future changes in sea levels, precipitation, and intensity of hurricanes.” But because the New York City region’s FEMA maps have been underway since 2010, they are exempt from the law.

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.

Click for a larger version. Graphic via NRDC.

“As a result, [FEMA maps] continue to underestimate the people, buildings and critical infrastructure at risk from flooding during future storms” states NRDC.

Investment and Reforms Needed

Flooding in downtown Manhattan after Hurricane Sandy. Photo credit: Patrick McFall via Creative Commons.

With more than $129 billion worth of property now officially at-risk from flooding, Stringer concludes that the City must move forward with “the necessary investments to protect our homes, our businesses and our neighborhoods from the future effects of climate change.”

These investments include surge barriers, artificial reefs, dunes, jetties, living shorelines, and floodwalls, which “have the potential to transform the City’s topography and protect our coastal areas.”

However, FEMA’s current mapping process does not take into account resiliency efforts, even though these enhancements “are proven to help stem the effects of localized flooding and substantially lower flood risk.” That means New Yorkers could continue to pay high flood insurance rates even though the risk of flooding has gone down.

“FEMA should be required to regularly review the efficacy of implemented resiliency measures on a regional basis, with an eye toward reducing premiums for homeowners in region’s that have chosen to invest in fortifying their shorelines,” states the report.

With Sandy’s historic impact still being felt two years later, it’s clear that effective preparation for the next storm—and effective protection of citizens—will require coordination and collaboration at all levels of government.