Modernizing Flood Maps

April 25, 2003
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FEMA’s Map Modernization Plan provides many opportunities for surveyors.



The Federal Emergency Management Agency (FEMA) developed the Map Modernization Plan to update its 100,000 panel flood map inventory and modernize the Flood Hazard Mapping Program, a plan to provide communities with updated, accurate and extensive information, resulting in safer communities. Since the plan was established in 1997, it has continually evolved as new products, processes and technical specifications have been developed, but its purpose remains the same: to use state-of-the-art technology to alert and educate the public of the risks of flooding. If fully funded, the Map Modernization Plan will revolutionize flood hazard mapping and provide numerous opportunities to surveyors, engineers and map makers who support FEMA’s mapping program.

FEMA’s Map Modernization Plan

Flooding stands as the single most pervasive disaster hazard facing the nation. It causes $6 billion in property damages annually with losses continuing to rise. However, flood hazard maps represent the nation’s greatest tool in protecting citizens from the devastation of flooding. FEMA estimates that, if map modernization is fully implemented, more than $48 billion of potential flood damage will be avoided over 50 years through the safer siting and design of new buildings and infrastructure.
    The cornerstones of map modernization are to cost-effectively:

  • Develop accurate flood hazard data for all floodprone areas nationwide to support sound floodplain management and prudent flood insurance decisions;

  • Provide the maps and supporting data in digital format to improve the efficiency and precision with which mapping program customers can use this information;

  • Integrate community and state partners into the mapping process to build on local knowledge and enhance community ownership of new products; and

  • Improve customer services to speed processing of flood map orders and raise public awareness of flood hazards.

Map modernization has yet to be implemented because funding for FEMA’s Flood Hazard Mapping Program has been limited. However, the 2003 federal budget that President Bush signed on Feb. 20, 2003, includes a $150 million down payment on map modernization, which will be used to upgrade the nationwide flood map inventory. FEMA plans to stretch this funding by obtaining an aggregate state/regional/local contribution of at least 20 percent for all newly initiated projects with a mapping partner. In addition, the Bush Administration has indicated a long-term commitment to map modernization. The president’s budget for the U.S. government for 2004 proposes $200 million in new discretionary funding for flood hazard mapping.

Strategy for Implementing Map Modernization

The preferred format for upgraded flood maps will be countywide digital Flood Insurance Rate Maps (FIRMs) that meet new specifications. Flood map upgrades and new flood maps will fall into three major categories:
  • Level 1 - Flood Map Upgrade: This includes converting manually produced, paper maps to new FIRM specifications using a current, digital base map; enhancing, when cost-effective, the flood theme (e.g., redelineation of floodplain boundaries using improved topography or limited detailed studies to update approximate flood zones); incorporating the results of Letters of Map Change; and fixing mismatched flood hazard information across community and county boundaries.

  • Level 2 - Flood Map Upgrade: This includes updating flood hazard data through a more comprehensive study or restudy of flooding sources as well as all of the components in a Level 1 flood map upgrade. A Level 2 map upgrade provides more detailed flood hazard data and is significantly more expensive than a Level 1 map. This additional detail may be necessary for land use management purposes, especially in rapidly developing communities that allow floodplain development.
  • Flood Map Creation: This involves developing flood hazard data and producing digital FIRM products for flood-prone communities currently unmapped by FEMA.

FEMA plans to allocate the $150 million in new funding to mapping projects in all states. The proposed approach for the initial upgrade of the flood map inventory using the 2003 funding will be:

  • Level 1 flood map upgrades of larger numbers of maps with flood hazard data improvements when possible;

  • More comprehensive Level 2 flood map upgrades for communities with the most pressing flood data needs; and

  • Creating digital flood maps for the most at-risk, flood-prone, unmapped communities.

Level 2 upgrades and flood map creations will require significant engineering work and support from surveyors. These upgrades involve detailed studies, which are performed to develop new flood hazard data such as water-surface elevations and floodway encroachments. Detailed studies are engineering analyses that require surveys of channel bathymetry, bridges, culverts and weirs.

All funding will be obligated to projects in 2003, and the map upgrades will be completed from 2003 through 2006. During this period, the primary focus of FEMA’s mapping staff at the national and regional offices will be to manage and oversee the initiation and completion of mapping projects and further build the capabilities of FEMA’s state and local partners.

Digital map with an aerial image base map and flood hazard data developed using high-resolution elevation data and a detailed engineering analysis.

Map Modernization Case Study

The cooperation between FEMA and the North Carolina Floodplain Mapping Program (see POB articles posted at www.pobonline.com on May 1, 2001; May 31, 2001; May 3, 2002; and Oct. 31, 2002) provides an excellent example of the new flood mapping paradigm. Through this partnership, which includes 15 other federal agencies and numerous county and municipal agencies, the state is planning to produce approximately 10,000 new flood maps using a unique map format that serves both state and federal needs.

By bringing more than $26 million in state funding and aggressively coordinating with numerous partners, North Carolina has prepared over 1,000 flood maps for 12 counties in the past year. Previously, the flood maps for only one North Carolina county were updated per year. Several components of the program demonstrate how FEMA’s Map Modernization Plan will be implemented and how it will revolutionize flood hazard mapping, including:

Basin-Wide Approach

Engineering and mapping is scheduled in three phases and geared toward river basins as opposed to political subdivisions. Hydrologic and hydraulic analyses performed for an entire watershed can be performed seamlessly and more efficiently due to economies of scale.

Extensive Scoping

Scoping determines what areas are flood-prone and need to have flood hazard data developed, what methods will be used to generate that hazard data and how that data will be presented on new FIRM panels. Previously, when a flood mapping effort was initiated, only 10 to 20 percent of the flooding sources in a community were considered for new analysis. Under the North Carolina program, the extensive scoping effort reviewed data for all flooding sources in a community using a five-step process that allowed for public input during each step.

Remote Sensing

New digital elevation data have been acquired for 26,475 square miles in North Carolina using LiDAR (Light Detection and Ranging). This technology has provided high-resolution topographic data now used for all new engineering analyses and floodplain delineations.

Automated Analyses

Technology now allows automated hydrologic and hydraulic techniques to take advantage of capabilities within GIS or other software applications to support the production of flood maps and supporting databases. North Carolina’s program has emphasized engineering studies and developing flood elevations for areas currently mapped with approximate flood zones. With the availability of high-resolution, digital elevation data, automated analyses are being performed along 8,970 stream miles for only 20 percent of the cost of detailed studies prepared just several years earlier.

Paper FIRM developed in the 1980s using manual cartographic techniques.

Digital Data

In the past, the products distributed for a flood study included a report and paper maps. Under the Map Modernization Plan, flood maps will be digitally produced and allow other products, such as standard and enhanced databases, to be distributed. All new maps and digital supporting data (e.g., aerial imagery, vector base mapping, topographic data and databases) are provided via the Internet, improving customer service and enhancing public awareness of flood risk.

Outreach & Training

An important component of the state’s program is an extensive community outreach strategy, which includes the creation and maintenance of a public website (www.ncfloodmaps.com) to disseminate information. Training is provided to assist community officials in using the new data and maps to implement floodplain management activities. By reaching key stakeholders in a proactive manner, it is believed that the maps will be used to their full potential and will promote further discussion in local governments regarding pre-disaster planning.

Creating a Reality

Surveyors, engineers and map makers who support FEMA’s mapping program are employing emerging tools and implementing innovative ideas to produce cost-effective flood maps. The 2003 federal budget provides funding to not only begin the update of the nation’s flood maps, but to continue to upgrade processes to take advantage of technological advances. Opportunities are provided and the needs and expectations of flood mapping stakeholders and the public are met.

More information is available on FEMA’s website at www.fema.gov/mit/ tsd/mm_main. htm.

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