*Indicates that a definition is taken, with minor editing, from the Federal Emergency Management Agency Website.1
The terms are ordered so that each definition(s) builds on a previous definition(s) and thus are not listed alphabetically as in a glossary.
Flood*: A general and temporary condition of partial or complete inundation of normally dry land area.
Floodplain*: Any land area susceptible to being inundated by water from any source.
Flood frequency: Probability, expressed as a percentage, that a given flood stage elevation will be equaled or exceeded in any given year.
Direct physical loss by or from flood*: Loss of or damage to insured property caused directly by a flood.
Flood risk: The expected direct physical loss (flood damage) in any year from a range of floods with a specified frequency.
1% annual chance flood*: A flood stage elevation that has a 1% chance of being equaled or exceeded in any given year; also known as a 100-year flood or base flood.
Mitigation*: Action to reduce or prevent future damage, preferably before a disaster strikes (see Floodplain management).
Floodplain management*: The operation of an overall program of corrective and preventive measures for reducing flood damage, including an emergency preparedness plan, flood-control works, and floodplain management ordinances (see Mitigation).
Community*: A political entity that has the authority to adopt and enforce floodplain ordinances (engage in mitigation) for the area under its jurisdiction as a requirement of the National Flood Insurance Program. In most cases, a community is an incorporated city, town, township, borough, or village or an unincorporated area of a county or parish.
Flood hazard boundary map*: Official map of a community issued by FEMA on which the boundaries of the flood, mudflow, and related erosion areas of varying flood risk have been designated.
Special flood hazard area*: The land in the floodplain within a community that is subject to a 1% or greater chance of flooding in any given year. Also called the regulatory floodplain.
Base flood elevation*: The elevation of surface water resulting from a flood that has a 1% chance of occurrence in any given year.
Negatively elevated structure*: A structure in the Special Flood Hazard Area with a ground floor elevation below the BFE.
National Flood Insurance Program flood zone*: A geographical area shown on a Flood Hazard Boundary Map or a Flood Insurance Rate Map that reflects the severity or type of flooding in a Special Flood Hazard Area. Zones associated with the letter A refer to flood elevations associated with the 1% annual chance flood. Zones associated with the letter X have a lower flood risk than those associated with the A zone. V zones are areas where the Base Flood Elevation also includes storm surge and wave effects.
Flood insurance rate map*: Official map of a community on which FEMA has delineated Special Flood Hazard Areas, Base Flood Elevations, and risk premium zones applicable to the community.
Map Revision*: A change in the Flood Hazard Boundary Map or Flood Insurance Rate Map for a community that reflects revised zone, base flood, or other relevant information.
Pre-FIRM building*: A building constructed or substantially improved on or before December 31, 1974, or before the effective date of the initial Flood Insurance Rate Map of the community, whichever is later.
Subsidy: Direct financial assistance intentionally given to a business or individual and paid from general government revenues.
Cross-subsidy: Direct financial assistance intentionally given to a business or individual by using a good or service paid for by charging higher prices to other users of the good or service.
Actuarial pricing principles: A set of guidelines recognized by professional actuaries as guides for setting premiums. A rate should reflect the expected value of future claims, provide for all the costs of risk transfer (insurance program administration), and provide for all costs associated with individual risk transfer by trying to avoid cross-subsidization among policyholders. If those three principles are met, premiums should not be excessive, inadequate, or unfairly discriminatory (American Academy of Actuaries, 2012).
National Flood Insurance Program servicing agent*: A corporation, partnership, association or any other organized entity that contracts with FEMA to service insurance policies as direct business.
Write-Your-Own program*: A cooperative undertaking of the insurance industry and FEMA that began in October 1983. It operates within the context of the NFIP and involves private insurance carriers that issue and service NFIP policies.
Rating: The guidance used by an NFIP servicing agent to calculate the premium for a specific property. The guidelines are in NFIP rating tables and are used to estimate premiums on the basis of various characteristics, NFIP flood zone locations, elevations, and coverage levels.
Elevation certificate*: A certificate that verifies the elevation data on a structure on a given property relative to the ground level. It is used by local communities and builders to ensure compliance with local floodplain management ordinances and is also used by insurance agents and companies in setting premiums for flood insurance policies.
NFIP risk-based premium: The premium for a group of policies that, as legislative and administrative constraints allow, will meet actuarial pricing guidelines.
Pre-FIRM subsidized premium: A premium made available to owners of properties that were located in a Special Flood Hazard Area before the first Flood Insurance Rate Map for the community was issued. The rate per $1,000 of coverage for the first $60,000 of coverage is less than the NFIP full-risk rate. There is no cross-subsidization in the NFIP full-risk rating table to offset the loss of premiums revenues due to the lower than NFIP full-risk premiums.
Grandfathered premium*: A premium for a post-FIRM building that was constructed in compliance with the floodplain management regulations in effect at the start of construction. Such a premium will continue even if a FIRM revision results in a higher Base Flood Elevation. There is a cross-subsidization in the NFIP full-risk rating table to offset the loss of premium revenues due to the lower than NFIP full-risk premiums.
Community Rating System (CRS)*: A program developed by FEMA to provide incentives for communities that have gone beyond the minimum NFIP floodplain management requirements and developed extra measures to provide protection from flooding.
Community Rating System discounted premiums: Discounted premiums reduced from NFIP full-risk premiums that are available for some properties in a community if the community adopts one or more NFIP flood risk management actions. The discount varies with the community actions and is available to properties that would be paying NFIP full-risk premiums and are in a Special Flood Hazard Area. There is cross-subsidization in the NFIP full-risk rating table to offset the loss of premium revenues due to the lower than NFIP full-risk premiums.
Mandatory purchase*: The requirement, under the provisions of the Flood Disaster Protection Act of 1973, that individuals, businesses, and others buying, building, or improving property that is located in identified Special Flood Hazard Areas in participating communities to purchase flood insurance as a prerequisite for receiving any type of direct or indirect federal financial assistance (for example, any loan, grant, guaranty, insurance, payment, subsidy, or disaster assistance), if the building or property is the subject of or security for such assistance.
Takeup rate: Ratio of the number of properties that have NFIP flood insurance policies to the number of eligible properties. Takeup rate can be affected by the mandatory purchase requirement and by voluntary purchase decisions of property owners and renters.