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DHS FEMA NFIP Services - eWaterwark Article
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Mid-Course Adjustment: Flood Maps
If you want to know how to get to where you are going, you'll probably consult a paper map or online
mapping service. In the world of flood mitigation, preparedness, and response, those who want to locate
risks within the floodplain consult FEMA's Flood Insurance Rate Maps (FIRMs).
Today, millions of people in the United States and its territories depend on the accuracy of the FIRMs
for information about where and how to build safely, rate policies for flood insurance coverage, manage
development, site mitigation projects, and rebuild after floods occur. FEMA is committed to providing
consumers with up-to-date, accessible, and accurate flood hazard mapping information.
Modernizing FEMA's Maps
Flood Map Modernization is a multiyear Presidential initiative supported by Congress that is
directed at improving and updating the Nation's flood hazard identification maps. The updated maps
will reflect new data as well as improved technologies for identifying flood hazards.
With any long-term initiative, it is a good practice periodically to evaluate the original goals,
seek feedback from stakeholders, and make adjustments as appropriate to ensure that the initiative
is being implemented in the best manner possible.
When the Map Modernization initiative approached the halfway point in its funding, FEMA performed
a mid-program evaluation that considered input from Congress, the U.S. Government Accountability
Office (GAO), the Department of Homeland Security's Inspector General, and other stakeholders. As
a result of this evaluation, FEMA is now implementing changes to its Map Modernization Program that
will result in better-targeted and more accurate flood data, as well as the production of digital
flood maps for a significant portion of the United States.
A Targeted Shift
From the beginning of this initiative in 2003, Map Modernization has focused on creating a digital
flood layer for all communities at risk of flooding. However, recommendations from stakeholders
during the initiative's first years have indicated a preference for FEMA to focus on developing
flood maps that meet new higher standards for mapping and for a shift in resource allocation to
those communities that have the most significant flood risk, even though it would result in a delay
in map production for communities with a lower risk of flooding.
FEMA believes the "adjusted" course it is now implementing for Map Modernization is responsive to user
and Congressional input and, based on improved data collected as part of the initiative, reflects a
sound direction for the future. The Map Modernization Program's modified objectives are now: (1)
producing new digital products; (2) providing new, updated, or validated engineering analyses; and (3)
integrating the 2005 Floodplain Boundary Standard into the digital maps.
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Original Course |
Adjusted Course |
| Percentage of mapped stream and coastal miles meeting 2005 Floodplain Boundary Standard |
57% |
75% |
| Percentage of mapped stream and coastal miles with new, updated, or validated engineering analysis |
22% |
30% |
| Percentage of population covered by maps with new, updated, or validated engineering analysis |
15% |
40% |
| Percentage of land area of continental United States covered by digital flood maps |
100% |
65% |
| Percentage of U.S. population covered by digital flood maps |
100% |
92% |
This table shows that, with the adjusted course, more engineering analysis will take place and there
will be a higher level of compliance with the Floodplain Boundary Standard than would have been
possible under the course originally intended. On the other hand, there will be a decrease in the
total land area being mapped and the percentage of the U.S. population receiving a digital map
product.
The Floodplain Boundary Standard
In response to input from Congress and the GAO as well as recent experience gained in converting
paper maps to digital format, FEMA implemented an additional mapping standard midway through the
initiative that is related to the conversion of digital flood boundaries. This new standard is
called the Floodplain Boundary Standard, and it requires matching the available flood boundary from
the paper map to the best available topographic information, and then merging both into the digital
format. This process results in a digital map whose floodplain boundary line corrects any
discrepancies in the paper map's boundary that may have existed either because topographic information
was insufficiently detailed when the paper map was created or as a result of the conversion process.
Map Modernization Progress Report
The major advances FEMA has made in the process for modernizing FIRMs for the United States are
listed below.
Standardized Guidelines
FEMA's release of Guidelines and Specifications for Flood Hazard Mapping Partners was a major
achievement in coordinating and fostering accuracy and consistency in flood mapping. This document
and its appendixes define the technical requirements and product specifications for flood hazard
maps and related NFIP products, and also reflect changes to processes and products that have come
about with Map Modernization, such as data capture standards and guidelines.
The MHIP
Another critical implementation aid developed by FEMA is the Multi-Year Flood Hazard Identification
Plan (MHIP), which details FEMA's plan for prioritizing and delivering modernized flood maps
nationwide. A standardized procedure for annually refining the MHIP is based on input from States
and other stakeholders.
Floodplain Boundary Standard
Section 7 of FEMA's FY04-FY08 MHIP established a Floodplain Boundary Standard that must be met for
a map to be considered "modernized." Guidance on implementation of the standard was issued to mapping
partners in September 2005. This single step goes a long way toward alleviating the concerns of map
users that boundaries improperly drawn on the paper maps would simply be transferred to the digital
maps. With the Floodplain Boundary Standard in place, this potential inaccuracy is avoided.
Mapping Information Platform
In 2004, FEMA launched the Mapping Information Platform (MIP), a Web-based infrastructure that
provides the ability to manage, extract, share, and produce mapping information. FEMA's mapping
partners post and share data developed for flood study projects on the MIP. The site is enhanced
continually to provide upgraded engineering and mapping tools to FEMA's mapping partners.
Risk-Based Mapping Priorities
FEMA uses a process called sequencing to compare flood risks between communities and then prioritize
mapping for the higher risk area. Based on a series of factors (such as population and growth,
housing units, flood insurance policies and claims, and repetitive flood losses), every county in
the U.S. has been assigned a "risk factor" that is used by FEMA when determining allocation of
study funds and priorities. In general, counties with the highest risk factor are high-priority
targets for new maps. Sequenced priorities are communicated to the FEMA Regions and to the State,
where further adjustments in priority may be based on local conditions.
Census Block Groups
Beginning with Fiscal Year 2006 funding (October 1, 2005), sequencing has been based on prioritized
census block groups rather than on prioritized counties. Block groups are the smallest geographic
unit for which the U.S. Census Bureau tabulates sample data. This adjustment allows for additional
focus on those areas that comprise 90 percent of the Nation's flood risk, and account for 92 percent
of the Nation's population.
Although 10 percent of the flood risks in the country have received a lower priority as a result
of the Map Modernization Program's mid-course adjustment, it remains FEMA's goal to map 100
percent of the United States.
Stream Mile Measurements
The improved detail and accuracy available with digital mapping techniques is enabling FEMA to
shift from using map panels to using stream miles (including shoreline for the open ocean, lakes,
and ponds) as a measure of progress. There are roughly 3 million stream and coastal miles of
floodplains in the United States. Approximately 1 million of these lie within Federal lands such
as national parks and military bases. Of the remaining 2 million stream and coastal miles that are
or could be at risk of flooding due to development, about 1 million have been the subject of some type
of flood hazard analysis.
Initially, counting map panels was a convenient way to inventory flood maps because each covered a
given area and the number remained fairly constant for a region. With the development of Geographic
Information Systems (GIS) technology, the scale of a flood map now can readily be tailored to
whatever its use. Therefore, the size of the "panels" and the number of panels needed to cover the
country are no longer constant.
On the other hand, the number of stream and coastal miles in the U.S. is fixed and thus provides a
standard against which progress can be measured. Using stream miles rather than rectangular panels
also allows depiction of a specific potential hazard so that differing vulnerabilities to flooding
can be targeted individually. Further, use of stream miles permits more precise identification of
areas that need additional attention, such as new flood data or a review of whether the mapping
standards are being met along that reach of stream. As a result of the mid-course adjustment, 40
percent of the U.S. population will have maps that encompass stream miles based on new, updated,
or validated engineering analysis.
Map modernization will not eliminate the use of panels. They continue to be an effective tool for
allowing insurance agents and building officials to make key insurance and mitigation decisions that
are tied to a specific panel location, and aid in tracking past decisions.
Looking Ahead
From the inception of the Map Modernization initiative and continuing through to the present,
there always has been an identified need for a post-Map Modernization phase that will account
both for map maintenance and for other unmet needs. Specifically, areas that must be addressed
during that phase include:
- Completion of a digital flood layer for the Nation, focusing on the low-risk areas that were
not addressed during the Map Modernization initiative
- Meeting additional needs for new flood data that either had not been identified or could
not be accommodated during the initiative
- Normal maintenance activities associated with the 5-year review mandated under Section 575
of the National Flood Insurance Reform Act of 1994 that 20 percent of the existing maps will be
evaluated each year to determine what revisions and updates are needed
- Ensuring that, as technology improves, the modernized maps and the process FEMA uses to
produce them evolve as well
The conversion from a paper map system to a digital system is a monumental step forward and
revolutionizes how flood maps are maintained, stored, and distributed. The use of digital tools is
resulting in dramatically improved efficiency in the process of making, using, and updating flood
maps and also enhancing their accuracy.
FEMA's mid-course adjustment in implementing the Map Modernization initiative will yield cost-effective
benefits in terms of timely realization of digital flood map coverage for those areas in which it is
most needed. Over the long term, these modernized flood maps will more accurately portray flood hazards
so that risks to life and property can be assessed and appropriate action taken.
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| Last Modified:
Friday, 21 January 2011 |
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