Advisory Base Flood Elevations (ABFE) Frequently Asked Questions
Prior to Hurricane Sandy, the coastal flood study underway for the New Jersey and New York coastlines was only partially complete. Because existing Flood Insurance Rate Maps (FIRMs) for these areas were developed more than 25 years ago, and the updated FIRMs were not finalized, FEMA developed Advisory Base Flood Elevation (ABFE) maps in late 2012 and early 2013 to support reconstruction efforts using the partially completed flood study.
For most communities in the region, the ABFE maps have now been replaced by preliminary FIRMs as the most recent flood hazard information available from FEMA. An historical archive of all ABFE information released is available through the FEMA Best Available Data archive page. More information about these products is also available through the FAQ below and in the Document Library.
What are Advisory Base Flood Elevation (ABFE) maps?
Following large storms, such as Hurricane Sandy, FEMA performs an assessment to determine whether the 1% annual chance flood event, shown on the effective FIRMs adequately reflects the current flood hazard. In some cases, due to the age of the analysis and the science used to develop the effective FIRMs, FEMA determines there is a need to produce ABFEs. ABFEs are provided to communities as a tool to support them in recovering in ways that will make them more resilient to future storms.
ABFE maps were developed for the New Jersey/New York coastal region following Hurricane Sandy because in some cases, the effective FIRMs were more than 25 years old and did not accurately reflect coastal flood hazards in the area.
How were the ABFE maps developed?
The ABFEs are based on the partially completed coastal flood study underway before Hurricane Sandy. Information about the methodologies, assumptions and data sources used to develop the Advisory information is available through the New York/New Jersey Coastal Advisory Flood Hazard Information Development Report.
Where do I get the ABFE maps?
For most communities in the region, the ABFE maps have now been replaced by preliminary FIRMs as the most recent flood hazard information available from FEMA. An historical archive of all ABFE information released is available through the FEMA Best Available Data archive page.
How were the impacts of Hurricane Sandy factored into the ABFE information?
The specific magnitude and track of Hurricane Sandy were not factored into the updated coastal analysis used for the ABFEs. FEMA uses statistical probabilities of historic storms as part of the updated coastal analysis, which does not include any individual event from past history. Historical storms of similar paths and magnitudes to Hurricane Sandy are accounted for within the statistical analysis, and the inclusion of Hurricane Sandy would not affect the outcomes of ABFEs or the depiction of the advisory flood zones. More information is available in the New York/New Jersey Coastal Advisory Flood Hazard Information Development Report.
Why do the ABFE maps show some elevations lower than Hurricane Sandy elevations?
ABFEs are based on the 1% annual chance flood event. ABFEs may show elevations lower than Hurricane Sandy in certain areas because Sandy was a more extreme event than the 1% annual chance flood in those areas. The elevations of the 1% annual chance flood are the National Flood Insurance Program standard for floodplain management. It is important to note that buildings constructed to this standard are still vulnerable to the effects of larger events like Hurricane Sandy.