Flood Hazards

The term "100-year flood" is misleading. It is not the flood that will occur once every 100 years. Rather, it is the flood elevation that has a 1 percent chance of being equaled or exceeded each year. Thus, the 100-year flood could occur more than once in a relatively short period of time. The 100-year flood, which is the standard used by mo st Federal and state agencies, is used by the National Flood Insurance Program (NFIP) as the standard for floodplain management and to determine the need for flood insurance. A structure located within a special flood hazard area shown on an NFIP map has a 26 percent chance of suffering flood damage during the term of a 30-year mortgage. (From: http://www.fema.gov/faq/faqDetails.do?action=Init&faqId=1014.)

For most waterways, the floodway is where the water is likely to be deepest and fastest. It is the area of the floodplain that should be reserved (kept free of obstructions) to allow floodwaters to move downstream. Placing fill or buildings in a floodway may block the flow of water and increase flood heights. Because of this, your community will require that you submit engineering analyses before it approves permits for development in the floodway. (From: http://www.fema.gov/plan/prevent/fhm/fq_fld01.shtm.)

Floodplains are the lowland and relatively flat areas adjoining inland and coastal waters, and those other areas subject to flooding. (From: A Unified National Program for Floodplain Management, FEMA, 1986.)

There are several ways to access flood zone information:
Contact your local government and ask to be directed to the department in charge of the Community Map Repository to view the hard copy FIRM. A listing of some community contact numbers can be found at this link http://www.fema.gov/fema/csb.shtm.

The Mitigation Division, a component of the Federal Emergency Management Agency (FEMA), manages the National Flood Insurance Program. The three components of the National Flood Insurance Program (NFIP) are:


Nearly 20,000 communities across the United States and its territories participate in the NFIP by adopting and enforcing floodplain management ordinances to reduce future flood damage. In exchange, the NFIP makes Federally backed flood insurance available to homeowners, renters, and business owners in these communities. Community participation in the NFIP is voluntary.

In addition to providing flood insurance and reducing flood damages through floodplain management regulations, the NFIP identifies and maps the nation's floodplains. Mapping flood hazards creates broad-based awareness of the flood hazards and provides the data needed for floodplain management programs and to actuarially rate new construction for flood insurance.

From: http://www.fema.gov/about/programs/nfip/index.shtm

For "Answers to Questions About the National Flood Insurance Program" go to http://www.floodsmart.gov/floodsmart/pages/about/nfip_about.jsp

The Elevation Certificate (FEMA Form 81-31) is an important administrative tool of the NFIP. It is used to determine the proper flood insurance premium rate; it can be used to document elevation information necessary to ensure compliance with community floodplain management regulations; and it may be used to support a request for a Letter of Map Amendment (LOMA) or Letter of Map Revision based on fill (LOMR-F).

Because a FEMA Elevation Certificate is needed before most flood insurance policies can be issued under the NFIP, communities are encouraged to obtain and maintain Elevation Certificates so that residents and businesses can easily obtain flood insurance. In order to participate in the NFIP Community Rating System (CRS), communities must require and maintain the Elevation Certificate for all new and substantially improved structures.

Under the NFIP, communities are required to obtain the elevation of the lowest floor (including basement) of all new and substantially improved structures and maintain a record of all such information [44 CFR 60.3(b)(5) - Requirement to Obtain Lowest Floor Elevation in Zone A; and 44 CFR 60.3 (e) (2) Requirement to Obtain Elevation of Lowest Horizontal Structural Member in Zone V]. A community''s permit file must have an official record that shows new buildings and substantial improvements in all identified Special Flood Hazard Areas (SFHAs) are properly elevated. This record is needed to show that buildings constructed in the floodplain are compliant with the community's floodplain management ordinance. While communities can create their own forms for documenting elevation information, Communities participating in the Community Rating System (CRS) are required to use the FEMA Elevation Certificate for documenting the elevation of various building elements (section C of the Elevation Certificate) and for documenting building compliance including the lowest floor determination (section G of the Elevation Certificate which is the Community Information section). The advantage of using the Elevation Certificate is that it will help the property owner in obtaining flood insurance since this form is used in determining a flood insurance rate.

Elevation Certificate http://www.fema.gov/library/viewRecord.do?id=1383

FEMA Elevation Bulletin http://www.fema.gov/library/viewRecord.do?id=1727

For further information, go to:

http://www.fema.gov/plan/prevent/floodplain/nfipkeywords/elevation_certificate.shtm

(From: http://www.fema.gov/plan/prevent/fhm/fq_term.shtm)

Zone A
Zone A is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the Flood Insurance Study by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no Base Flood Elevations or depths are shown within this zone. Mandatory flood insurance purchase requirements apply.

Zone AE and A1-A30
Zones AE and A1-A30 are the flood insurance rate zones that correspond to the 100-year floodplains that are determined in the Flood Insurance Study by detailed methods. In most instances, Base Flood Elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.

Zone AH
Zone AH is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding with a constant water-surface elevation (usually areas of ponding) where average depths are between 1 and 3 feet. The BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.

Zone AO
Zone AO is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. The depth should be averaged along the cross section and then along the direction of flow to determine the extent of the zone. Average flood depths derived from the detailed hydraulic analyses are shown within this zone. In addition, alluvial fan flood hazards are shown as Zone AO on the FIRM. Mandatory flood insurance purchase requirements apply.

Zone AR
Zone AR is the flood insurance rate zone used to depict areas protected from flood hazards by flood control structures, such as a levee, that are being restored. FEMA will consider using the Zone AR designation for a community if the flood protection system has been deemed restorable by a Federal agency in consultation with a local project sponsor; a minimum level of flood protection is still provided to the community by the system; and restoration of the flood protection system is scheduled to begin within a designated time period and in accordance with a progress plan negotiated between the community and FEMA. Mandatory purchase requirements for flood insurance will apply in Zone AR, but the rate will not exceed the rate for unnumbered A zones if the structure is built in compliance with Zone AR floodplain management regulations.

For floodplain management in Zone AR areas, elevation is not required for improvements to existing structures. However, for new construction, the structure must be elevated (or floodproofed for non-residential structures) such that the lowest floor, including basement, is a maximum of 3 feet above the highest adjacent existing grade if the depth of the base flood elevation (BFE) does not exceed 5 feet at the proposed development site. For infill sites, rehabilitation of existing structures, or redevelopment of previously developed areas, there is a 3 foot elevation requirement regardless of the depth of the BFE at the project site.

The Zone AR designation will be removed and the restored flood control system shown as providing protection from the 1% annual chance flood on the NFIP map upon completion of the restoration project and submittal of all the necessary data to FEMA.

Zone A99
Zone A99 is the flood insurance rate zone that corresponds to areas of the 100-year floodplains that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No BFEs or depths are shown within this zone. Mandatory flood insurance purchase requirements apply.

Zone D
The Zone D designation on NFIP maps is used for areas where there are possible but undetermined flood hazards. In areas designated as Zone D, no analysis of flood hazards has been conducted. Mandatory flood insurance purchase requirements do not apply, but coverage is available. The flood insurance rates for properties in Zone D are commensurate with the uncertainty of the flood risk.

Zone V
Zone V is the flood insurance rate zone that corresponds to the 100-year coastal floodplains that have additional hazards associated with storm waves. Because approximate hydraulic analyses are performed for such areas, no BFEs are shown within this zone. Mandatory flood insurance purchase requirements apply.

Zone VE
Zone VE is the flood insurance rate zone that corresponds to the 100-year coastal floodplains that have additional hazards associated with storm waves. BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply.

Zones B, C, and X
Zones B, C, and X are the flood insurance rate zones that correspond to areas outside the 100-year floodplains, areas of 100-year sheet flow flooding where average depths are less than 1 foot, areas of 100-year stream flooding where the contributing drainage area is less than 1 square mile, or areas protected from the 100-year flood by levees. No BFEs or depths are shown within this zone.

For general information, go to FEMA's FLOODSMART.GOV website, http://www.floodsmart.gov/floodsmart/pages/index.jsp and click on "Estimate Your Premium." Consult with your insurance agent to get actual premium costs or get assistance locating an agent at the above website using the "Find an Agent" button.