FEMA is Revising its Levee Analysis and Mapping Approach

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FEMA is assessing the approach used to analyze areas on the landward side of non-accredited levees on Flood Insurance Rate Maps (FIRMs), and is developing more precise methods to identify flood hazards in these areas.

FEMA's Existing Analysis Method for Levees

When preparing a flood risk study, FEMA treats accredited levees (levees that meet the requirements of Title 44, Chapter 1, Section 65.10 of the Code of Federal Regulations, or 44 CFR § 65.10) as providing protection against a 1-percent-annual-chance (or 100-year) flood event. In other words, FEMA assumes that an accredited levee will prevent the flow of water on the landward side of the levee during a 1-percent-annual-chance flood. Levees that cannot be shown to meet the criteria in 44 CFR § 65.10 are non-accredited. FEMA's current procedures when analyzing the flood hazards associated with non-accredited levees assume that the levee does not sufficiently reduce flood risk, and that the water would flow both on the landward side of the levee and on the side of the flooding source.

The Need to Change FEMA's Levee Analysis Approach

Although FEMA's current procedures are technically sound, FEMA recognizes the benefits of a more precise modeling approach to determine flood zones and establish insurance rates. FEMA has been engaged in a comprehensive review of its National Flood Insurance Program to identify reforms that will enable us to better address flood risks. A part of that review has included working with members of Congress and other stakeholders regarding FEMA's approach to mapping flood risk with respect to levees. As a result, FEMA has developed a revised set of procedures that account for several typical non-accredited levee scenarios. These scenarios characterize actual conditions that a community may encounter when addressing non-accredited levees or levee systems.

The Process

FEMA convened a multidisciplinary Project Team with representatives from FEMA, the U.S. Army Corps of Engineers (USACE), and experts from the academic and engineering communities. The Project Team explored a spectrum of options, evaluated analysis and mapping methods for multiple levee scenarios, assessed their feasibility using several key criteria, and solicited feedback from internal and external stakeholders.

The selected methods were then tested for effectiveness in representative case studies using a select number of theoretical situations that simulated real life examples that communities might face. Following this testing process, an Independent Scientific Body (ISB) made up of recognized experts and certified professional engineers was convened by the National Institute of Building Sciences (NIBS) to review the methods and provide comments. Information about the ISB panel can be found at http://floodsrp.org/panels/. The Panel ID for this effort is FEMA061711.

Community Involvement in the Development Process

FEMA recognizes the importance of community involvement in developing revised procedures and incorporating feedback from local stakeholders and officials who may be impacted by them. Following the review of the revised procedures by the ISB, FEMA convened a Community Roundtable with a representative number of local executives, floodplain managers, and levee owners to gather their feedback on the revised procedures. More information is available in the Community Roundtable fact sheet.

FEMA has provided the public an opportunity to hear about the revised procedures. FEMA has made the approach available for public review and comment through the Federal Register.

Once the revised analysis and mapping procedures for non-accredited levees have been fully vetted with a wide array of stakeholder groups, FEMA will develop guidance on how the process will work and on how to implement the procedures. FEMA will solicit feedback and comments from key external stakeholders and flood risk study practitioners to help with developing the guidance.

Public Review Period

From December 15, 2011 to January 30, 2012, the public had the opportunity to provide input on the levee analysis and mapping approach developed by FEMA. The “Public Review and Comment” period is a federally regulated process for receiving, managing and incorporating stakeholder feedback.

During the 45-day period, FEMA received over 1400 individual points from over 160 commenters. Following the Public Review Period, FEMA will compile and analyze the data and work on appropriate revisions to the approach over the coming months.

The “Revised Analysis and Mapping Procedures for Non-Accredited Levees: Proposed Approach for Public Review” is available on the FEMA Library until the approach is finalized.

In addition to the Public Review document available, FEMA held three online public webinars from December 21, 2011 to January 12, 2012. Over 400 attendees participated in the webinars, heard the presented approach, and had the opportunity to ask clarifying questions. A copy of the narrated public webinar presentation with slides is available for download. Questions and answers from the Forums will be available soon.

Benefits of the New Approach

There are several benefits to the revised analysis and mapping procedures as they are currently being presented:

  • Improved models and tools that may provide more precise flood risk information behind non-accredited levees
     
  • The ability to analyze the hazard associated with specific levee reaches, rather than the entire system. This will include identifying individual reaches that are fully compliant with FEMA's regulations for being accredited
     
  • Increased flexibility with no one, broad procedure that will apply in all cases. Rather, FEMA will work with the local community to address their specific levee situation and
     
  • A more collaborative levee evaluation process that works with a Local Levee Working Group.

Important Considerations for Communities Affected by the New Approach

FEMA is NOT seeking regulatory changes to 44 CFR §65.10 during this process. Regulatory changes would not be feasible given the time sensitivities for this revised analysis and mapping effort. Levee owners will still be required to provide the documentation and certifications as outlined in 44 CFR § 65.10 for levees and levee systems to be shown on the map as accredited.

The revised procedures will result in a change to the way FEMA analyzes areas on the landward side of non-accredited levees. However, FEMA cannot determine whether a community's Special Flood Hazard Area (SFHA) will increase or decrease based on the revised procedures until FEMA collaborates with the community and conducts the levee-specific analysis.

If a flood risk study in your community is impacted by non-accredited levees or levee systems, it likely has been placed on hold during development of the revised analysis and mapping procedures. For questions or comments about a study in your particular community, please contact your FEMA Regional Office.

If a community wishes to move forward on a project before the new levee analysis and mapping approach is implemented, it can submit a formal written request to the Regional Office including the community name, levee name, request for issuance of panels for their community, and a statement requesting the finalization of maps. If the Region determines it is feasible to move forward, the project can continue using the current approach.

As part of this collaborative process, FEMA will provide targeted outreach materials and briefings to explain the revised analysis and mapping procedures and how they are different from the current approach.

Residual Flood Risk Must Still Be Mitigated

Although the analysis and modeling of levee-affected areas has been placed on hold, the flood risk that these levee systems were built to reduce still remains. No levee can completely eliminate flood risk. Living with levees is a shared responsibility, and local community officials and communities as a whole should remain engaged in flood risk management activities. It's important for all to know the risk, know their role in helping to reduce that risk, and what specific actions they can take, including the purchase of flood insurance to further reduce the financial risk associated with living and working in levee-affected areas.

For More Information

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Last Updated: 
08/01/2012 - 14:04
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