Coastal Flood Risk Study Process

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United States map showing the preliminary map release schedule through color coding.

In this page you will find information about the efforts to scientifically study and understand coastal risks as part of the FEMA’s Risk Mapping, Assessment and Planning (Risk MAP) effort in partnership with other federal agencies, states, regional authorities, tribal nations, communities and non-profit organizations. 

The expansion of communities into undeveloped coastal areas increased during the last several decades. This development puts many citizens at risk from coastal storms and flooding along the Atlantic and Pacific Oceans, the Gulf of Mexico and the Great Lakes. In addition, the current Flood Insurance Rate Maps (FIRMs) are outdated in many coastal areas due to the age of the data and methodologies used in producing the effective FIRMs, some of which date back to the mid-to-late 1970s. Major changes in National Flood Insurance Program (NFIP) policies and methodologies have occurred since the effective date of many coastal studies, creating the need for updates to reflect more detailed and complete hazard information. FEMA is updating the flood hazard information presented in coastal Flood Insurance Studies (FISs) and on Flood Insurance Rate Maps (FIRMs) where updates are needed in populated coastal areas.

Information about Coastal Flood Insurance Rate Maps (FIRMs)

  • A Flood Insurance Rate Map is an official map of a community on which FEMA has delineated Special Flood Hazard Area (SFHAs)  applicable to the community. As part of its Risk MAP effort, FEMA scientists and engineers work with other federal, state, regional, community, tribal, non-profit, nongovernmental and private-sector partners to determine the flood risk for properties along the populated U.S. coastline. If you live in a populated area along the coast, your community may have recently received or, may soon receive, an updated coastal FIRM and FIS.

  • Within the coastal Special Flood Hazard Area (SFHA), there are two primary zones: Zone VE and Zone AE.  Zone VE, also known as the Coastal High Hazard Area, has a wave component that is three feet in height or greater. The coastal Zone AE has a wave component of less than 3 feet in height.  Base Flood Elevations (BFEs) will vary in each zone. Changes in flood zones and BFEs can have a significant impact on building requirements and flood insurance costs. BFEs may differ dramatically within a small area because waves can diminish in size over a short distance upon encountering obstructions or steep ground. Some areas also have a Limit of Moderate Wave Action (LiMWA) shown on the FIRM, which is the location where the 1-percent-annual-chance wave height equals 1.5 feet. To communicate the higher risk that exists in the area, FEMA began showing the LiMWA on Flood Insurance Rate Maps because the 1.5-foot breaking wave in the LiMWA zone can potentially cause foundation failure. Communities are encouraged to adopt building construction standards similar to Zone VE in those areas.

  • For more on Coastal Zones and LiMWA, see the graphic below and click to watch the Coastal Zones/LiMWA Animation.

    Animated graphic of the coast showing the base flood elevation, stillwater elevation and other coastal terms while describing flood zones and the Limit of Moderate Wave Action.
  • Flooding occurs not only in high-risk V-zones and A-zones but also in low to moderate risk areas, shown as X Zones on a FIRM. Anyone can be financially vulnerable to floods. People outside of high-risk areas file over 20% of NFIP claims and receive one third of disaster assistance for flooding.

  • Throughout the lifecycle of each coastal flood risk study, FEMA encourages community and public involvement and feedback. The regulatory requirements for coordination with community officials, including the appeal process, are documented in the Code of Federal Regulations at Title 44, Chapter I, Parts 66 and 67.

  • After a FIRM has been adopted, there are several processes available to change the map due to map scale limitations or manmade or natural changes in floodplains. Contact your local Floodplain Administrator or a Map Specialist at the FEMA Map Information eXchange toll free, at 1‑877-FEMA MAP or by email at FEMAMapSpecialist@riskmapcds.com for more information. 

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The Coastal Flood Risk Study Process

  • The coastal Flood Insurance Rate Map (FIRM) update process begins in the Discovery phase, in which FEMA meets with coastal communities, state representatives and other stakeholders to share data and collaboratively determine needs and identify the best path forward. 

  • The coastal FIRM update is generally conducted along the entire state coastline or across an entire lake basin (i.e., for the Great Lakes). This approach saves technical and data-gathering resources over the traditional county-by-county FIRM update approach. In addition to providing more accurate flood risk information, these studies make efficient use of limited tax dollars by generating new data that can be used to support other studies on coastal erosion, land use planning, estuaries/wildlife habitat and other coastal topics. Given the size and scope of these studies, a multitude of partners and communities work in cooperation towards a common goal. 

  • After a study is conducted, preliminary FIRMs and FISs are distributed within each affected community. Information about the analysis used to create the new preliminary FIRMs is included in the FIS in order to provide transparency to the community and enable them to evaluate the technical approach and the science behind the study. 

  • The FIRM is referred to as the "regulatory product” of the study, meaning the FIRM is used to determine who must buy flood insurance and where flood plain development regulations apply. Under the Risk MAP Program, additional "non-regulatory products” may also be included to help communities and property owners plan for resilience. An example of such non-regulatory products include a coastal depth grid, which shows how deep the water would be during the 1-percent chance flood at any given location, areas where the risk is greater than on the previous map, wave heights and severity of flooding and erosion risk determination.

  • Following issuance of the Preliminary FIRM, FEMA Regional Offices will usually hold formal coordination meetings with community officials and open houses for the public to explain changes to the FIRM, answer questions and obtain feedback.

  • Afterward, a 90-day appeal period will be initiated, during which time the community and others may appeal the proposed flood hazard information by submitting scientific or technical data that proves the flood hazard information is shown in error on the preliminary FIRM and/or FIS. Please note all comments or appeals to FIRMs should be submitted through the community, therefore community officials should be contacted with any concerns. For additional information on FEMA's appeals process, please see the Changes to FEMA's Appeal Process Fact Sheet.

  • At the end of the 90-day appeal period or upon resolution of all appeals, FEMA will issue a Letter of Final Determination (LFD) that establishes that the flood hazard information is final. The LFD initiates the six-month compliance period during which the community must adopt or amend its floodplain management regulations to reflect the updated flood hazard information shown on the FIRM and FIS.

  • The FIRM and FIS will become effective following the six-month compliance period. After the six-month compliance period, flood insurance will be required for properties that are shown on the FIRM in the Special Flood Hazard Area (SFHA) and have a federally regulated or insured lender. The final FIRM will be available at a community’s local map repository and online through FEMA’s Map Service Center.

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To find out the progress of your community’s coastal mapping project, please visit the Risk MAP Progress website through Risk MAP webpage. This website offers an interactive map that allows users to zoom in, locate their community and click to learn about the project status (i.e. time frame for their preliminary and effective maps). A browser plug-in may be required to use this tool. If your community is participating in the NFIP, paper copies of the FIRMs and FIS reports are on file at the “Community Map Repository.”

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Last Updated: 
10/16/2014 - 08:59
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