Michigan Surveying, Inc.

Michigan Surveying, Inc.

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Flood Terminology Explained

Base Flood - The flood having a 1% chance of being equaled or exceeded in any given year.

Base Flood Elevation (BFE) - The elevation shown on the Flood Insurance Rate Map (FIRM) for Zones AE, AH, A1-A30, AR, AR/A, AR/AE, AR/A1-A30, AR/AH, AR/AO, V1-V30, and VE that indicates the water surface elevation resulting from a flood that has a 1% chance of equaling or exceeding that level in any given year.

Basement - Any area of the building, including any sunken room or sunken portion of a room, having its floor below ground level (subgrade) on all sides.

Breakaway wall - A wall that is not part of the structural support of the building and is intended through its design and construction to collapse under specific lateral loading forces, without causing damage to the elevated portion of the building or supporting foundation system.

Elevated Building - A building that has no basement and has its lowest elevated floor raised above the ground level by foundation walls, shear walls, posts, piers, pilings, or columns. Solid foundation perimeter walls are not an acceptable means of elevating buildings in V and VE zones.

Elevation Certificate - A certificate that verifies the elevation data of a structure on a given property relative to the ground level. The Elevation Certificate 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 the rating of flood insurance policies.

Enclosure - That portion of an elevated building below the lowest elevated floor that is either partially or fully shut-in by rigid walls.

Federal Emergency Management Agency (FEMA) - The federal agency within the Department of Homeland Security that is tasked with responding to, planning for, recovering from, and mitigating against man-made and natural disasters.

Flood - A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is the policyholder's property) from one of the following:

  • Overflow of inland or tidal waters

  • Unusual and rapid accumulation or runoff of surface waters from any source

  • Mudflow

  • Collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above

Flood Hazard Boundary Map (FHBM) - Official map of a community issued by the Federal Insurance Administrator, where the boundaries of the flood, mudflow, and related erosion areas having special hazards have been designated.

Flood Insurance Rate Map (FIRM) - Official map of a community on which the Mitigation Division Administrator has delineated both the special hazard areas and the risk premium zones applicable to the community.

Flood Zone (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 the area.

Floodplain - Any land area susceptible to being inundated by floodwaters from any source.

Floodplain Management - The operation of an overall program of corrective and preventive measures for reducing flood damage, including but not limited to, emergency preparedness plans, flood control works, and floodplain management regulations.

Lowest Floor - The lowest floor of the lowest enclosed area (including a basement). An unfinished or flood-resistant enclosure, usable solely for parking of vehicles, building access, or storage in an area other than a basement area, is not considered a building's lowest floor provided that such enclosure is not built so as to render the structure in violation of requirements.

National Flood Insurance Program (NFIP) - A federal program enabling property owners in participating communities to purchase insurance protection against losses from flooding. This insurance 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.

Non-Special Flood Hazard Area (NSFHA) - An area in a low to moderate risk flood zone (Zones B, C, X) that is not in any immediate danger from flooding caused by overflowing rivers or hard rains. However, it’s important to note that structures within a NSFHA are still at risk.

Participating Community - A community for which the Mitigation Division Administrator has authorized the sale of flood insurance under the NFIP.

Special Flood Hazard Area (SFHA) - A FEMA-identified high-risk flood area where flood insurance is mandatory for properties. An area having special flood, mudflow, or flood-related erosion hazards, and shown on a Flood Hazard Boundary Map or a Flood Insurance Rate Map as Zone A, AO, A1-A30, AE, A99, AH, AR, AR/A, AR/AE, AR/AH, AR/AO, AR/A1-A30, V1-V30, VE, or V.

Standard Flood Insurance Policy (SFIP) - Policy issued to insure a building and/or its contents.

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 the area.


Use of acronyms and initials has been limited, but some terms are used so often the acronyms are practical and of assistance to the reader.

BFE -Base Flood Elevation
CBRA -Coastal Barrier Resources Act
CBRS -Coastal Barrier Resources System
CLOMA -Conditional Letter of Map Amendment
CLOMR -Conditional Letter of Map Revision
CLOMR-F -Conditional Letter of Map Revision Based on Fill
CRS -Community Rating System
DHS -U.S. Department of Homeland Security
FDPA -Flood Disaster Protection Act
FEMA -Federal Emergency Management Agency
FHBM -Flood Hazard Boundary Map
FIRA -Flood Insurance Reform Act
FIRM -Flood Insurance Rate Map
FIS -Flood Insurance Study
ICC -Increased Cost of Compliance
LODR -Letter of Determination Review
LOMA -Letter of Map Amendment
LOMC -Letter of Map Change
LOMR -Letter of Map Revision
LOMR-F -Letter of Map Revision Based on Fill
NFIP -National Flood Insurance Program
NFIRA -National Flood Insurance Reform Act
OPA -Otherwise Protected Areas
PMR -Physical Map Revision
RCBAP -Residential Condominium Building Association Policy
SDF - Special Direct Facility
SFHA -Special Flood Hazard Area
SFHDF -Standard Flood Hazard Determination Form
SFIP -Standard Flood Insurance Policy
WYO -Write Your Own

Courtesy of FEMA-National Flood Insurance Program www.FEMA.gov