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Coastal Flood Maps

Coastal Flood Maps

FEMA is issuing new maps to show current flood risks along the coasts. For many areas the risks have changed. Learn when the preliminary maps for your area will be released, and see how storm surge and wave action can affect coastal risk.

New Digital Maps For U.S. Coasts

FEMA is conducting a multi-year effort to study and map coastal flood risks, using updated data and the latest technology. By 2018, new flood maps will be released for more than 75 percent of coastal areas. The new maps will replace those that are based on old studies, some of which were performed more than 30 years ago. Flood risks change over time due to land development, erosion, increasing storm intensity, and other causes. In addition, mapping technologies have improved. Therefore, the risks shown on the new digital maps may be higher or lower than on earlier maps. The maps are used for flood insurance rating purposes and are known as Flood Insurance Rate Maps (FIRMs).

See the flood map update schedule

High-Risk and Moderate- to Low-Risk Areas

The maps delineate areas of high flood risk, defined as Special Flood Hazard Areas (SFHAs). These areas have a 1 percent or greater chance of flooding in any year. Within an SFHA, most mortgage lenders require building owners to have flood insurance. For flood insurance rating purposes, the maps show different zones, each corresponding to a different level of risk. For coastal areas, the high-risk zones must take into account risk from not only the storm surge, but also from wind-driven waves. The maps currently do not project the effects of sea level rise due to climate change. They show the current risk, based on historical data and modeling results. A typical new coastal map will show the following:

The Limit of Moderate Wave Action (LiMWA) is the inland boundary line of waves with heights between 1.5 and 3 feet

Zone VE—a high-risk area where storms drive waves landward at heights of 3 feet or more.

Coastal Zone AE—a high-risk area subject to wave heights of 1.5 to 3 feet. For flood insurance purposes, this zone is treated as Zone AE; however, communities are encouraged to regulate construction to include Zone VE standards as these waves can still cause significant damage to coastal structures.

Zone AE—a high-risk area subject to waves less than 1.5 feet in height. This will be separated from the Coastal AE zone by the Limit of Moderate Wave Action (LiMWA). A LiMWA may not always be present, in which case, only Zone AE is shown.

Zone X—areas of moderate risk (shown as a shaded zone X) or low risk (zone X). While the risk is reduced, nearly 25 percent of all flood claims come from these zones.

CBRA Zones—In 1982, Congress passed the Coastal Barrier Resources Act (CBRA) to protect barrier islands, known as Coastal Barrier Resources Systems. A subsequent act in 1990 tripled the size of the system and created Other Protected Areas (OPAs). These CBRA zones are along the coastlines of the Atlantic Ocean, Gulf of Mexico, and Great Lakes. Federal spending and financial assistance are restricted, and flood insurance is not available for buildings constructed after their area became a CBRA zone or OPA.

Learn more about flood maps and flood zones.

Coastal Zones

Learn about the three basic coastal zones and one new zone (LiMWA) in the new NFIP maps. Watch Now

Using the Base Flood Elevation

The elevation that floodwaters will reach or exceed during the 1 percent annual chance flood (also known as the "100-year" flood) for a given location is called the Base Flood Elevation (BFE). Essentially, that elevation separates a high-risk zone from a moderate- to low-risk zone, and those zones are separated by a line on the Flood Insurance Rate Maps (FIRMs). One thing to keep in mind, however: Floodwaters do not stop at a line on a map.

Flood insurance rates are calculated using a number of factors, but a key factor for homes in high-risk areas is the elevation of a property compared to the BFE. To determine these elevations and the cost of insurance, you will need to provide your insurance agent an Elevation Certificate. If you do not have a recent one, check with your local floodplain manager to see if one is on file. If not, you will need to hire a surveyor to complete the Elevation Certificate.

Learn more about elevation and Elevation Certificates.

When Coastal Flood Maps Change

A new map may show that your community's flood risks have changed. For a given property, the risk may be higher or lower than before. If a new map shows your property at higher-risk (mapped from a moderate- to low-risk zone into a high-risk A zone, or from a high-risk A zone to an even higher risk V zone), or shows a higher BFE, you may still be able to save on flood insurance. The NFIP's grandfathering option allows rates to be calculated based on a previous zone or lower BFE. However, be aware that a provision of the Biggert-Waters Flood Insurance Reform Act of 2012 (BW-12) that has not yet been implemented may alter the grandfathering option in the future.

What's My Flood Risk?

Visit FEMA's Flood Map Service Center to locate your flood map to help determine your flood risk.

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Last Updated: Tuesday, 27-Sep-2016, 1:47 PM (EDT)

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