FEMA Flood Insurance Rate Maps

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FEMA Flood Insurance Rate Maps

By: Danny Greenwood

For: Geog 483 Nature of Geographic Information Systems, Spring 2013 Assignment: Project 3

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Abstract:

In an attempt to regulate flood insurance rates uniformly in the United States the Federal Emergen-cy Management AgenEmergen-cy(FEMA) has created a mapping system to generalize the risk of floods based on geographic features. These maps determine policies which communities can either benefit from or become ostracize by flood risk management. The quality , accuracy, and availability of these maps is crucial to determine where and how plans and policies in all levels of government and private industry assess their risks in flood zones.

Introduction:

In 1968 the federal government created the National Flood Insurance Program to identify flood risks and to reg-ulate insurance policies(Burby, 1990). Soon after this creation congress passed a series of laws which regreg-ulated the flood insurance industry(Coble, 2013). With this change in legislation arose the need for a national mapping standard which unified and categorized flood risks into distinct zones. This provided the framework for the type of flood management standards we have today which both federal, state and local governments as well as private industry follow.

The federal governments role in flood rates became regulatory when they assessed the failure of the private insur-ance industry. Also local governments failed to assess the risks of floodplains into their building codes which helped the federal government intact a more direct role. The mismanagement by both parties demanded federal attention mainly due to the catastrophic effects of flooding on property as well as the effects on lives. In order to enact the regulation the NFIP used a method of coercion. They required all new homes and building be raised to the level of a rated 100 year flood stan-dard. The 100 year flood is not a flood that happens every 100 years but instead a flood that has a one percent probability of happening in any given year (Burby, 1990). The areas that comply to the NFIP standards are allowed to participate in the federal disaster assistance program and are qualified to purchase flood insurance.

Since the enactment of the NFIP, amendments have been made to better meet its overarching goal and to enhance participation. In 1973 the flood disaster protection act was passed and with it came methods to entice local governments and property owners to adopt the insurance programs(Burby, 2001). Failure to do so resulted in a loss of aid to help strengthen flood structures or reduce hazards. It also required that home owners with federally backed loans obtain flood insurance. This brought more participation into the program. In 1994 the program brought into effect an incentive meth-od which gave rate breaks to certain insurance holders which mitigated flometh-od hazards through better flometh-od avoidance methods.

With these measures in place and an increasing NFIP participation rate, a mapping assistance program became a very important task. FEMA set out to produce these maps and provide them to the public for floodplain management and insurance purposes. FEMA then designated standards so that insurance rates could reflect the risks of homes within certain areas. With accurately calculated risks based on actual flood hazard characteristics, FEMA expects that market incentives will improve protection of homes and the prevention of building in high risk areas.

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The Evolution of Flood Insurance Maps

As stated earlier, FEMA is the responsable agency for delivering quality and reliable flood maps to the public. Over the years the program has changed their methods of mapping as well as delivering mapping products. These changes came in light of both consumer demand and the need to provide attributal flood risks in a visual representation.

FIRM, Q3, And DFIRM Maps:

The Ferderal Insurance Rate Maps(FIRMS) are based on the studies of regions called Flood Insuarance Studies (FIS).

These studies are complied and help create the FIRM’s of counties and municipalities as well as compare maps with flood risks. The studies include analysis of waterways, geography, geology, population, flood mitigation and history, climatology, and many other factors of flood conditions specific to the study area(FEMA, 2013). These early model maps were paper based and later were digitalized on FEMA’s website, known as FIRMetts. The FIRM maps include basic hydrographic and hypo-graphic features like highways, basic roads, and waterways. Although features help with the detail of the map, the purpose of features in FIRMS’s are to reference special flood hazard zones within the area(SFHA). These hazard zones are ranked based on the chance of certain magnitude floods happening in any given year(i.e. 100yr flood). The floodplains, floodways, and elevations are categorized into the zoning process as well as zones that are not effected by floods.

The FIRM maps use vertical datum NGVD29 and NAVD88 datum based on the year that they were produced(FE-MA, 2007). The elevation values are used to measure the zones in base elevation flood levels. The base elevation flood level corresponds to the base flood known as the 100 year flood.

Figure 1: FIRMette of Sutter County, CA. Notice that there is a general level of topography (Feather River, Streets, etc.). Also notice there are distinct zones which in this example is shaded grey and labeled A. FEMA does provide a scale bar as well as information about the location and effective data. This is a primitive example of flood maps available today.

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A drastic change in technology and increasing demand for more functional maps caused FEMA to enact a policy to create spatial referenced digital maps for public use. FIRMS obviously became an outdated model due to the fact that they could not be adequately used with GIS technologies. The creation of Q3 addressed a main issue, that Flood maps without georeferenced capabilities are not practical for general use. FEMA describes Q3’s as representations of FIRM’s for desktop mapping(FEMA, 2013A). Mainly this product enhanced the capabilities of emergency response methods by FEMA as well as improving the NFIP’s flood insurance program. One main issue with Q3’s however is that they are not certified to be used to delineate flood risk boundaries (FEMA, 2013A). In fact the Q3 maps are scanned images of FIRM paper maps which have been vectorized in order to represent coordinates. Like FIRM maps, Q3 maps contain zones for flood boundaries but does

not include hydrographic and hypograpic features. Q3 data is available for purchase at the FEMA map service center(here). Q3

data is also provided by certain local or state governments, i.e. figure 2 Q3 layer which was provided by the State of Washing-ton Ecology Department. A depiction of available Q3 data by county is shown in figure 3.

X X X X X X X X X X X X A X X X X X X X X X X X X X A X X X X X X A X X X A A A A X A AE A A A A A A A X X A A A A X A A A A A A A A A A X A A A X A X A X AA A A X A X A A A _A

Sources: Esri, DeLorme, NAVTEQ, TomTom, Intermap, increment P Corp., GEBCO, USGS, FAO, NPS, NRCAN, GeoBase, IGN, Kadaster NL, Ordnance Survey, Esri Japan, METI, Esri China (Hong Kong), swisstopo, and the GIS User Community

00.51 2 Miles

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Figure 2: FEMA Q3 Map of Adams County Washington. Layered onto Topographic Base Layer.

Source: FEMA MSC DFIRM Database; Department of Ecology, Washington State; Esri Basemap. Created by Daniel Greenwood (25 April, 2013)

DFIRM’s are better representations of FIRM maps as well as legal representations of flood hazard zones. They have been created to replace the Q3 digi-tal maps in an attempt to provide more accurate dig-ital GIS data(FEMA, 2005). DFIRMS are created us-ing local vector control maps or USGS Digital Ortho Quads. They are better equipped for the modern age of technology because they have been standardized to meet stricter requirements. Once FEMA obtains flood hazard zone data they convert that data into a standard projection, the traverse mercator, and stan-dard coordinate system, UTM, with NAD83 datum. This process makes the entire mapping system much more accurate and conformal than its predecessors.

An important feature that Q3 maps does not provide and DFIRMS do are base flood elevations(B-FE). Base elevation profiles are crucial for surveyors and insurers because they provide a compatible array of damage risks at certain heights in a 100 year flood occurrence. DFIRM methodology requires base ele-vation data be certified, guaranteeing more accurate measurements. In Figure 3, the base elevation is la-beled with green lines and located within the AE des-ignated flood zone. Values represent the height of a 100 year flood for that particular area(FEMA, 2000). For example, a base flood of 83 feet would result in a total rise of flood water of 83 feet in a 100 year flood scenario. Figure 3 shows these BFE’s in areas that are located along the rivers and stream floodways.

As shown in figure 3, flood zones in DFIRM’s can be represented as polygons but can also be rep-resented as line features. FEMA also provides base national geodetic control points for elevation profiles which were not depicted in the figure but are available for display. The Features in DFIRM data include water bodies, streams, transportation lines and Digital Ele-vation Models.

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Sources: Esri, USGS, NOAA

0 1 2 4Miles

N

Flood Zone 500 Year Flood A AE AH AO X X Levee Protected Base Flood Elevation

County Boundary State Highway Urban Area

Tigerline Edge Features

Sutter County FEMA Flood Zones

Figure 4: DFIRM Flood Zone Layers and Base Flood Elevations.

Source: FEMA DFIRM Database,U.S. Census Bureau Tigerline Shapefiles. Esri USGS and NOAA Basemap. Generated by Daniel Greenwood (25 April, 2013)

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sible in the new DFIRM Data. Although most of Sutter County is not completely mapped a variety of flood zone designations are made available for the unincorporated areas. Zones the start with “A” are considered the Special Flood Hazard Area’s, which means that they reside in a 100 year flood plain or a 1% annual chance flood. The 500 year flood zone flood zone (colored orange in figure 3) corresponds to a lower risk .2% chance of annual flood. Zone X is considered outside the flood hazard zone but still has insurance requirements.

Tracy Dr Augusta Ln G er m ai ne D r Ed w in D r Porto la V al le y R d Pebble Beach Dr Kevin Dr Sessler Pl Eli _Ct Sh ee na C t Sessler Dr Hazel Ave Rushing St Sa int _Jo hn_C t W in gf oot D r TRACY DR AUGUSTA LN G ERM A IN E D R PO RTO LA_V AL LE Y R_D RAJ CT PEBBLE BEACH DR KEVIN DR ED_W IN_D R SA IN T JO H N C T SES_SLE R PL SH EE N A C T ELDE N CT PI N EH U R ST D R

Sources: Esri, USGS, NOAA

FEMA Transport Lines

Tigerline Edge Features

An interesting look as line features is shown in figure 3. It is obvious from this depiction that FEMA line features have a considerable amount of error when compared to tigerline features. When showing highly detailed large scale maps FEMA line features should be used to reference flood hazard zones.

The Availability of DFIRM data has progressed steadily over the years since being mandated by congress. DFIRMS now effectively cover a majority of households in the U.S.(See figure 5). Like Q3 data, some state and local govern-ments provide DFIRM data free of charge. Data on the FEMA Map Service Center can be downloaded for a fee.

Figure 5: Tigerline and FEMA Transportation lines. Source: FEMA DFIRM Database, U.S. Census Bureau Tigerline Shapefiles. Generated by Daniel Greenwood (27 April, 2013)

Figure 6: DFIRM Data Availability.

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Controversies and Conclusion:

While changes to insurance zones are occurring with updated DFIRMS, many residents are left wondering what new zone designation their properties may fall in. Notice that in figure 3, only about a third or less of the county is actually includ-ed in the flood zone study. This is because FEMA is waiting for local approval on a new levee enhancement project which will take place sometime in the next few years. Therefore, areas that are not mapped and will not be until the local construction process is completed. This creates a problem of stretching out the DFIRM mapping process and halts construction proposals as well as consumer choices until rates are determined.

Accuracy of flood hazard areas is also a concern. Because of the workload FEMA has encountered in creating maps it has taken millions of dollars and years to complete just a portion of the participating areas. Updating these maps in order to reflect the changes in local conditions is nearly impossible. Thus NFIP rates cannot achieve the accuracy that would lead to desired market conditions and properly assessed flood condition risks. Another failure of flood maps in cooperation with FEMA’s objectives are that maps are produced more so to reflect insurance needs and less for development and planning of flood zones(Burby, 2001). Thus flood damages continue to increase instead of decrease.

FEMA has also started instituting higher rates for areas that have recent history of catastrophic flood damage. Efforts

to enhance the overarching goal of flood damage prevention have lead the way to even more legislation. New York and the East Coast is a prime example of this new policy. Proposed increases in rates due to the flooding caused by Hurricane Sandy is justified by the damage caused that proved the existing map zoning system inaccurate. FEMA gives owners a choice in high risk flood zones to either raise their homes base elevation or experience drastic increases in insurance rates. An esti-mated increase of some homes effected could see their rates jump from $1,000 a year to $15,000 a year(Samuelson, 2013). In an already stricken community this policy does not bode well. It also reflects how FEMA’s flood designations fail at really determining flood risks.

In light of the problems created by the task of mapping flood hazard zones there are also encouraging unseen added benefits from flood mapping. The improvements in emergency preparedness in times of flooding is the greatest feat. Because areas are better mapped with DFIRM data, geospatial analysts can quickly determine emergency response zones and then decipher accurate evacuation buffering zones(FEMA, 2013B). Because flood zones are provided as layers, other layers can be used to determine populations and housing characteristics which coincide with flood zones, saving both time and lives.

Overall the FEMA flood maps have come a long way. The changes from FIRMS to DFIRMS is indicative of growing needs for more sophisticated mapping products for an advanceing geospatial industry. Although there are some pitfalls as-sociated with the creation of flood maps, the fact that FEMA is moving in the right direction is encouraging.

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Burby, J. M. , Holway, R. J. (1990). The Effects of Floodplain Development Controls on Residential Land Values. Land Economics, Vol.66 (No.3) pg. 259-271 http://www.jstor.org/stable/3146728

Burby, R. J. (2001). Flood Insurance and Floodplain Management: The U.S. Experience. Environmental Hazards (2001 No.3) pg111-122

http://www.elsevier.com/locate/hazards

Coble, K. H. , Landry, C. E. , Petrolia, D. R. (2013). Risk Preferences, Risk Perceptions, and Flood Insurance. Land Economics, Vol.89 (No.2) pg. 227-245

http://muse.jhu.edu/journals/land_economics/summary/v089/89.2.petrolia.html

FEMA (2000). How To Read A Flood Insurance Rate Map Tutorial. Accessed April 25, 2013 From,

www.fema.gov/library

FEMA (2005). Digital Flood Maps: From Q3 Flood Data to DFIRMS. Accessed April 25, 2013 From,

www.fema.gov/library

FEMA (2013A). Frequently Asked Questions. Accessed April 25, 2013 From,

http://www.fema.gov/frequently-asked-questions

FEMA (2013B). GIS Tutorial Series 3. Acccessed April 27, 2013 From,

http://www.fema.gov/online-tutorials

Samuelson, (2013, April, 28) . Unfinished FEMA Flood Maps Put Sandy Victims In Limbo. Accessed April 30, 2013 From,

http://www.npr.org/2013/04/28/179568786/new-jersey-homeowners-say-flood-maps-will-add-huge-costs

Sources

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