Floodplain map


FEMA, FIRMs, and Flood Hazard Areas

03 September 2019 Edwin Friedrichs

Edwin Friedrichs, PE, PTP, discusses the meaning behind key terms that describe major precipitation events.


Discussions by government officials and water resources professionals about major precipitation events typically contain references to somewhat unfamiliar terms such as FEMA, FIRMs, or Flood Hazard Areas. But what do these terms truly mean?

Federal Emergency Management Agency

FEMA (Federal Emergency Management Agency) is an agency of the U.S. Department of Homeland Security initially created by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive Orders on April 1, 1979. The agency’s primary purpose is to coordinate the response to a disaster that has occurred in the U.S. and overwhelms the resources of local and state authorities.

Flood Insurance Rate Maps

A FIRM (Flood Insurance Rate Map) is created by FEMA and then utilized by the National Flood Insurance Program (NFIP) for floodplain management and insurance purposes. Digital versions of these maps are referred to as DFIRMs.

A FIRM generally shows:

  • Roads and map landmarks
  • Base flood elevations
  • Flood zones
  • Floodplain boundaries

As a property owner, a FIRM can be used to get a reliable indication of the flood zone designation of a particular parcel of land. It should be noted that these maps are constantly being updated due to changes in geography, construction and mitigation activities, and the understanding of changing meteorological conditions. Therefore, for the most up-to-date information, contact your insurance agent, insurer, or community floodplain manager. For more information about FIRMs, visit the FEMA Map Service Center. (NOTE: FIRMs do not include all types of flood risk and are meant to be used as a tool and not an exhaustive source.)

Flood Hazard Areas

Flood hazard areas identified on the Flood Insurance Rate Map are identified as a Special Flood Hazard Area (SFHA). A SFHA is defined as the area that will be inundated by the flood event having a 1% chance of being equaled or exceeded in any given year. The 1% annual chance flood is also referred to as the base flood, or the 100-year flood.

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