As a result, FEMA’s modeling overestimates the size (or extent) of the one-percent-annual-chance (aka 100-year) floodplain (i.e., where waters will reach during a flood that has a one percent chance of occurring each year). The City found technical and scientific errors in FEMA’s modeling that overestimate the height of flood waters during a one-percent-annual-chance flood event, the “Base Flood Elevation (BFE),” by between 1 and 2.5 feet across the city. **In October 2016, FEMA announced that it agreed with the City’s findings,** and that it would work with the City to revise the 2015 Preliminary FIRMs and issue new maps in the coming years that better reflect current flood risk. In June 2015, New York City filed a technical appeal of the Preliminary FIRMs. The issuance of the Preliminary FIRMs and FIS marked the first step in the official flood map update process, which included a public comment and a 90-day technical appeals period. In January 2015, FEMA released Preliminary Flood Insurance Rate Maps for New York City as well as the Preliminary Flood Insurance Study (FIS) for New York City, a narrative report of the city’s flood hazard. Find out more about understanding FEMA’s Flood Maps. Each flood zone tells homeowners what the risk is for flooding at their property. This area is also referred to as the Special Flood Hazard Area (SFHA) or the 100-year floodplain, and is broken down into smaller areas called flood zones. This high risk area has a one percent chance of flooding in any given year, and a twenty-six percent chance of flooding over the life of a thirty-year mortgage. These maps identify areas that are at high risk to flooding. In the end, the exact location matters less than the overall effect it has on the community and the City.FEMA creates Flood Insurance Rate Maps (FIRMs) that highlight flood risk and determine flood insurance and building code requirements. For instance, if the block next to yours flooded, there is a high likelihood that your block would be affected since you may not be able to go to the grocery store on that block, use that street for public transportation, or access the school nearby. Rebuild by Design chose an approach to include all block groups that touch the floodplain because we were able to use updated data, it gives a clearer picture of who will be most affected. New York City uses census data from 2010 2) New York City used an approach which counts floodplain blocks as those census (city) blocks whose geographic center intersects the PFIRM 2015 floodplain. These numbers are higher than New York City’s own estimates for multiple reasons: 1) These maps use data from American Community Survey which provides only block groups from 2018. The 2100 floodplain is derived from NPCC3’s 2100 100-year floodplain projection. The 2050 floodplain is derived from NPCC3’s 2050 100-year floodplain projection. The current floodplain boundaries are derived from PFIRM 2015. A block group is a contiguous cluster of census blocks, or city blocks.ĭownload maps here: Citywide, The Bronx, Manhattan, Queens, Brooklyn, and Staten Island.Īccording to US Housing and Urban Development’s (HUD) 2018 income brackets, a family of 3 is considered low income if their household income is less than $75,120. Using the American Community Survey (2018) population data, all NYC block groups that intersect the 100-year floodplain were included. Past disasters, such as Hurricane Sandy, and our recent experience with Covid-19, have laid bare the reality that these events disproportionately hurt the most vulnerable populations which can include characteristics such as socioeconomic status, race, ethnicity, language, age, health, and household composition. If the impacts of climate change are left unabated, by 2100, this number could rise to 2.2 million. Those communities have a 1% chance of experiencing a major disaster every year. We found that 14 percent of New Yorkers – 1.3 million people – live within or adjacent to the 100-year floodplain. Analyzing the floodplain reveals a larger story – the number of New Yorkers who are highly vulnerable to increased coastal storms is even higher than New York City has accounted for. As climate change causes a rise in sea levels and increases the likelihood of flooding and major storms, we need to better understand who will be at risk during these events.
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