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National Flood Insurance Program

US Federal insurance program

  • 19 min read
  • 9 chapters

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Through Insurance, Flood and Reinsurance

Flood insurance was generally provided by private insurers beginning in 1895, but after the Great Mississippi Flood of 1927, most private insurers concluded that flood risk was uninsurable at a price that consumers could afford given the catastrophic nature of flooding, as well as difficulties in creating accurate risk assessments for policy pricing and risks of adverse selection.

The NFIP is managed and administered by the Federal Emergency Management Agency (FEMA) through the Federal Insurance and Mitigation Administration (FIMA). The program is designed to provide an insurance alternative to disaster assistance to meet the escalating costs of repairing damage to buildings and their contents caused by floods. As of August 2017, the program insured about 5 million homes (down from about 5.5 million homes in April 2010), the majority of which are in Texas and Florida. The cost of the insurance program was fully covered by its premiums until the end of 2004, but it has had to steadily borrow funds since, primarily due to Hurricane Katrina and Hurricane Sandy, accumulating $25 billion of debt by August 2017. In October 2017, Congress cancelled $16 billion of NFIP debt, making it possible for the program to pay claims. The NFIP owes $20.525 billion to the U.S. as of December 2020.

Floodplain definition

The Federal Emergency Management Agency (FEMA) defines the floodplain as the area that would be flooded by a base flood, which is "the flood which has a one percent chance of being equaled or exceeded in any given year". In this sense, a base flood is synonymous with a 100-year flood and a floodplain is synonymous with a special flood hazard area. This base flood "is used in the National Flood Insurance Program (NFIP) to indicate the minimum level of flooding to be used by a community in its floodplain management regulations." FEMA explains regulatory floodplains in some places including hills as "critical determinations are made by evaluating your community’s rainfall and river flow data, topography, wind velocity, tidal surge, flood control measures, building development (existing and planned) and community maps."

Scientists and engineers use statistical analysis of streamflow data to determine the likelihood of flood elevations. Theoretically, in any given year:

  • a 100-year flood has a 1 percent chance (1/100 = 0.01 or 1 percent) of occurring and,
  • a 500-year flood has as a 0.2 percent chance (1/500 = 0.002 or 0.2 percent) of occurring.

However, these expected flood elevations actually occur more or less often than expected.

44 CFR § 9.4 defines parts of the floodplain as follows:

  • Floodway means that portion of the floodplain which is effective in carrying flow, within which this carrying capacity must be preserved and where the flood hazard is generally highest, i.e., where water depths and velocities are the greatest. It is that area which provides for the discharge of the base flood so the cumulative increase in water surface elevation is no more than one foot.
  • Flood Fringe means that portion of the floodplain outside of the floodway (often referred to as "floodway fringe").

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