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Oklahoma's Floodplain Management 101

Chapter 1 Appendix

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Appendix 1-1: National Flood Insurance Program

Created by Congress in 1968, the National Flood insurance Program (NFIP) is a nonstructural approach for the prevention of flood damage. The Federal Emergency Management Agency (FEMA), an agency part of the U.S. Department of Homeland Security, administers the NFIP. FEMA's regional offices are responsible for much of the contact with local communities.

The NFIP has two main objectives:

  1. To enable property owners in flood-prone areas to purchase reasonably priced flood insurance; and
  2. To reduce future property loss and loss of life from floods.

In order to accomplish these goals, the NFIP requires the local community to adopt floodplain management regulations before flood insurance is available. The local regulations must meet the minimum federal requirements in order for the community to participate in the Program. In short, the NFIP provides insurance to people living in flood-prone areas to cover future flood damages, while regulating future development in the floodplain that might require further expenditures for disaster relief (see Figure 1-3).

Community participation in the NFIP is voluntary. Each identified flood-prone Community must assess its flood hazard and determine whether flood insurance and floodplain management would benefit the community's residents and economy. However, if a community chooses not to participate after the flood hazard has been identified, there are several ramifications, in addition to the availability of flood insurance, that affect property owners. By law, if a flood disaster occurs in a nonparticipating flood-prone community, no federal disaster assistance will be provided. Also, grants, loans, or guarantees made by federal agencies, such as the Small Business Administration, Federal Housing Administration, and Veterans Administration, are prohibited for acquisition or construction in identified areas.

When a community enters the first phase of the program (the emergency phase), it agrees to adopt and enforce a floodplain ordinance that meets the minimum regulatory requirements. These ordinances require the community to

  • review all building permits for new construction and determine the flood zone
  • using the best available information, require that new construction
    have the lowest floor elevated to the 100-year flood level (nonresidential structures have the option to floodproof to the same level) under the minimum regulations;
  • Apply some requirements to existing structures if substantial improvement is made (any repairs, reconstruction or improvement which equals or exceeds 50 percent of the market value of the structure);
  • Require all manufactured homes in a flood zone to be elevated and anchored to resist flotation, collapse or lateral movement; and
  • Review all subdivision proposals and require any necessary revisions to minimize the flood damage potential.

For additional requirements and explanations, refer to your local ordinances. In this phase, a limited amount of federally subsidized insurance is available for all structures in the community regardless of their flood risk.

A community is eligible to enter the regular phase of the program when FEMA completes a detailed engineering study, which defines the flood hazard areas based on hydrologic, geologic, and topographic data, and produces a Flood Insurance Rate Map (FIRM). The community must adopt more stringent floodplain ordinances to enter this phase. When a community enrolls in the regular phase, more flood insurance coverage becomes available to property owners.

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Appendix 1-2: Reading the Flood Insurance Rate Map (FIRM)

A Flood Insurance Rate Map (FIRM) (see Figure 1-4) shows the floodway special flood hazard areas inundated by 100-year flood in dark gray, floodway areas in Zone AE in dark gray with black stripes, other flood areas (Zone X) in lighter gray and other areas (Zone X) in white.

To locate a site on the map, measure the actual distance on the ground between the site of concern and an identifiable point (bridge, river channel, reference mark or other landmark). Using the map scale, convert these figures to map units and plot the site on the map. For example, the point labeled My Project is 100 feet upstream from the landmark. It is located in the Special Flood Hazard Area.

Cutting across the floodplain are a series of lines, tagged with letters, called cross sections. Flood elevations are developed for each of the cross sections and displayed on flood profiles (see Appendix 1-3).

Communities use the information from the FIRM and flood profiles to regulate development in the floodplain to meet standards of the NFIP.

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Appendix 1-3: Reading a Flood Profile

A flood profile (see Figure 1-5) is a chart showing the elevation of the water surface during a flood event at particular locations along a river or stream. Flood insurance studies determine the elevation at the cross section marks for the 10-, 50-, 100- and 500-year events. The cross section locations can be more easily seen on the Flood Insurance Rate Map (FIRM).

  1. First, check the gridscales on the profile. On the example above, each line on the horizontal axis represents 50 feet along the stream. The vertical axis lines each represent a 0.5 foot change in elevation, NGVD (National Geodedic Vertical Datum).
  2. Next, locate the point of concern on the horizontal axis. This will be the distance from the reference point on the ground, measured in Appendix 1-2. On the example above, the point of concern is about 100 feet upstream (toward the "H" cross section location marker) from the identified landmark. The point of concern is the same point referred to as "My Project" on the above example and on the Flood Insurance Rate Map (FIRM) in Appendix 1-2.
  3. Now draw a line vertically from the point located on the horizontal axis (labeled "stream distance above mouth") until it intersects the line that represents the FLOOD EVENT of concern. The example shows this line intersecting the 100-year flood line. The 100-year flood elevation is the protection level of the NFIP.
  4. Finally, to determine the elevation, draw a line horizontally from the point on the 100-year flood line to the scale on the left, which represents the ELEVATION in feet, NGVD. In the example above the point of concern, based on the 100-year flood event, is 1,134.7 feet, NGVD. The 10-year flood elevation is 133.3 ft. NGVD and the 500-year flood elevation is 1,135.25 ft. NGVD.

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Appendix 1-4: The Floodway

  • Review all development proposals to determine if they are located within a designated floodway.
  • Ensure any development or encroachment (filling, etc.) within a designated floodway area that would cause no increase in the base flood elevation.

Communities participating in the Regular Phase of the National Flood Insurance Program (NFIP) may have a detailed Flood Insurance Study completed for them by the Federal Emergency Management Agency (FEMA). This study describes flood hazards in the community and, if done in enough detail, designates a regulatory floodway.

For purposes of the NFIP, a floodway is defined as the channel of a stream, plus adjacent overbank areas, that must be kept free of encroachment so that the 1% chance flood may be carried without substantial increases (one foot or less) in flood heights. A floodway divides the floodplain into two parts: the floodway and the flood fringe. The floodway is the area of the floodplain that must be removed to carry floodwaters so that flood damages are not increased in the remainder of the 100-year floodplain flood fringe.

The purpose of this requirement is to ensure that new development does not aggravate existing flooding conditions in the community. This objective is achieved through stringent control of development within a defined portion of the floodplain called the floodway. Within designated floodways, the community must not permit any development, new construction, substantial reconstruction, use, activity or encroachment which would cause an increase in the heights of the 100-year (base) flood.

While the floodway requirement does not automatically exclude all forms of development, it does mandate that the flooding effects of new development be calculated beforehand so that adverse effects can be avoided. In general, when confronted with an application proposing new development within a designated floodway, local permit officials should assume that the development will increase flood heights unless the applicant can demonstrate otherwise. Development proposals that are found by engineering analysis to have no effect on (or to lower) flood heights are acceptable. Such developments could include a “one-for-one” replacement of an existing structure by a building of equal dimensions and displacement; projects where a new floodway encroachment is satisfactorily offset by removal of an existing obstruction or by a compensatory excavation; or proposals where an improvement in channel flow will compensate for the adverse effect of the new encroachment. Also, depending upon the hydraulic characteristics of a particular floodway at a given site, it may be possible to design a new development project that does not increase flood heights; however, once again the burden of proof must be assumed by the applicant to document the contention of “no effect on flooding”.

A community that is participating in the NFIP must make sure new development in the floodplain meets the standards of the program. Essentially, these standards require that new structures be protected from the 1OO-year flood event or 1% chance flood. The level this flood reaches is called the Base Flood (or 100-year) Elevation (BFE). If a new structure is built with its lowest floor at or above the BFE, it should be safe from flood damage. But, what happens if the BFE is increased?

BFEs can be increased by obstructions in the floodplain. For example, if dikes are constructed on both sides of a river channel, they constrict the river’s floodplain, causing floodwaters to rise and back up, increasing flood heights upstream. To avoid the possibility of raising the BFE, the NFIP asks a community to reserve a portion of the floodplain (the floodway) nearest the channel to pass floodwater without causing a significant increase.

A significant increase has been determined by FEMA to mean a maximum one-foot rise in the BFE. This means that if all areas outside the floodway are obstructed or filled in, the BFE will not be raised by more than one foot. Any obstructions placed in the floodway then would exceed the maximum one-foot rise allowed by the NFIP regulations.

The floodway is an engineering concept that has been incorporated into the NFIP floodplain management criteria. Floodways are defined as the areas of land immediately adjacent to a stream or river channel which in times of flooding actually become the enlarged stream or river channel and carry the floodwaters with the highest velocity. Floodways are calculated by FEMA for the 100-year base flood for major rivers and streams as part of the Flood Insurance Study undertaken for a community. Floodways are shown in the community’s Flood Boundary and Floodway Map and new FIRMS prepared by FEMA, and data on their width, cross-sectional area and floodwater velocity are given in the Flood Insurance Study. When floodway delineations and data have been furnished by FEMA, the community is required to adopt a “regulatory floodway” and begin enforcing the “no encroachment” requirement through its zoning ordinance.

The floodway is determined by “squeezing in” a community’s floodplain boundary (done by a computer hydraulic model) until the Base Flood is raised one foot. Sometimes the rise will be less than one foot at certain points in order to keep the increase from exceeding one foot at other points within the study area or to avoid excessive velocity. This “squeezing in” simulates building a wall from both sides of the floodplain toward the center of the channel.

The “wall” could be fill, structures, a levee or physical obstruction. When the imaginary obstruction has constricted flood flow enough to raise the Base Flood Elevation one foot, the limits of the obstruction define the boundary of the floodway.

In the past, these boundaries were placed on a Flood Boundary Floodway Map (FBFM). Since FBFMs are no longer printed, they are now placed on the Flood Insurance Rate Map (FIRM) provided to the community along with the Flood Insurance Study.

Normally, floodway boundaries are determined by computer model applying the equal degree of encroachment rule. The rule requires that the quantity of floodwaters conveyed on both sides of the watercourse be reduced by an equal percentage when developing the encroached floodway boundary.

This rule is based on the legal need to treat similarly situated property owners in a similar manner. In practice, the rule is not always followed due to many factors, including property ownership, topography, existing development patterns and comprehensive land use plans. Any of these factors may justify modifications to the equal degree of encroachment rule. As such, FEMA generally works closely with a community in identifying boundaries to make sure the floodway that is defined meets NFIP standards and community needs.

Communities that have an identified floodway on an FBFM or FIRM must not allow any development in the floodway unless it can be shown that the development will not cause an increase in flood heights. Communities do this through their development permit system.

When reviewing permit applications in the floodway, the floodplain administrator must determine the extent of development. In some cases, it is apparent that the proposed development will cause no change in the existing topography (for example, a playground). However, in most cases, the administrator will NOT be able to determine whether the development will cause a rise in base flood elevations.

When the floodplain administrator is uncertain, the permit applicant must prove to the community that the proposed floodway development, along with similar future development assumed by the equal degree of encroachment rule will cause no increase in the BFEs. The applicant must use a registered professional engineer to analyze the development plans and assess how the BFEs will be affected. Unless this analysis proves the development will cause no rise in the BFE the permit application must be denied.

Structures existing in a floodway prior to the floodway identifications are “grandfathered in” but are subject to NFIP regulations. Any substantial improvements to such structures, however, must be in compliance with the standards.

Floodway areas can be utilized. There are several development activities that will not cause an increase in the BFE, yet can sustain flood damage without great economic loss. These might include agricultural uses that do not involve structures, parking lots, loading areas or landing strips; recreational uses, such as picnic grounds, golf courses, or swimming areas; and lawns, gardens or other uses incidental to residential structures. Additions to existing structures, which do not add to ground flood area, may be allowed if they do not exceed substantial improvement criteria. An engineering analysis is the final determinant in all cases.

Having an identified floodway on a FBFM or FIRM eases a community's task of administering its floodplain ordinance. When the floodway is identified, the floodplain administrator can determine if a proposed floodplain development is in the floodway. If it is in the floodway, it will cause a rise. Without the floodway, floodplain administrators should always question whether or not proposed developments will affect existing BFEs.

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Appendix 1-5: Questions and Answers about Flood Insurance

What is Flood Insurance?

The National Flood Insurance Program (NFIP) was created to provide affordable flood insurance to property owners in flood-prone areas and promote good floodplain management so future developments will not suffer damage from flooding. The NFIP is administered by the Federal Emergency Management Agency (FEMA) and carried out by local community administrators.

Who Can Buy Flood Insurance?

Flood Insurance can be purchased by anyone in a community participating in the NFIP, whether or not their property is in the floodplain Flood insurance is voluntary unless required as a condition of a mortgage.

Where Can I Buy Flood Insurance?

Any licensed property or casualty insurance agent can sell flood insurance.

What Does It Cover?

Any walled and roofed structure can be insured from direct loss caused by the general condition of flooding. Flooding is defined as a general and temporary condition of partial or complete inundation of normally dry land by the overflow of water, or; the unusual and rapid accumulation of runoff of surface waters from any source .

What About Basements?

For flood insurance purposes, a basement is defined as having its floor subgraded on all sides. The NFIP limits flood insurance coverage in basements and in areas below the lowest elevated floor or an elevated building. Items covered include:

  • Stairways and staircases attached to buildings, not separated by elevated walkways.
  • Sump pumps.
  • Well water tanks and pumps.
  • Oil tanks (and oil in them).
  • Cisterns.
  • Gas tanks.
  • Electric junction circuit boxes.
  • Furnaces and hot water heaters.
  • Clothes washers and dryers.
  • Food freezers.
  • Air conditioners.
  • Heat pumps, and
  • Pumps and/or tanks used in conjunction with solar energy systems.

Items not covered include:

  • Finished basement walls, floors, ceilings and other improvements to a basement except those needed for fire proofing.
  • Enclosures below lowest elevated floor of elevated buildings.
  • Contents, machinery and equipment in basements, other than those specifically listed as being covered, and Contents below lowest elevated floor of elevated buildings.

How much does it cost?

Depending on if your community is in the Emergency or Regular Phase of the program, each policy premium differs.

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Appendix 1-6: FEMA Fact Sheet

FACT: Most homeowners insurance policies do not offer protection against flood damage.

FACT: Ninety percent of all disasters in the U.S. are flood related.

FACT: You are four times more likely to experience a flood than a fire if you live in a high risk flood zone, or Special Flood Hazard Area (SFHA).

FACT: Flood insurance is available through the federal government’s National Flood Insurance Program (NFIP), which is administered by the Federal Insurance and Mitigation Administration, a part of the Federal Emergency Management Agency. Flood insurance can be purchased through any licensed property/casualty insurance agent or through many private insurance companies that are now writing flood insurance under arrangements with the FIMA.

FACT: Flood insurance is required by law. Congress passed the Flood Disaster Protection Act of 1973, and the National Flood Insurance Reform Act of 1994 mandating at all federally insured or regulated lenders require flood insurance for mortgages and other loans on buildings and manufactured (mobile) homes located in SFHAs.

FACT: Almost any building with at least two walls and a roof may be insured if it is principally above ground and located in a community participating in the NFIP. Coverage is also available for buildings under construction.

FACT: The average premium for an NFIP flood insurance policy is $300 per year for approximately $85,000 worth of coverage. For those not in an SFHA, but still exposed to a risk, there is a low cost policy referred to as the Preferred Risk Policy, available for as little as $106 per year. Nearly one-third of our claims come from these lower risk areas.

FACT: Flood insurance is available for buildings in communities that have agreed to adopt and enforce sound floodplain management practices. Currently, there are over 18, 000 communities participating in the NFIP throughout the United States and our overseas territories.

FACT: While there are more than 3 million flood insurance policyholders, estimates are that of flooding.

FACT: Businesses may also be insured through the NFIP.

FACT: Contents of insurable, fully enclosed buildings may be covered by a separate policy, making flood insurance available to renters, too.

FACT: There is normally a 30-day waiting period between the time flood insurance is purchased and the time coverage is in force.

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Appendix 1-7: Principle Features of Increased Cost of Compliance (ICC) Coverage

The following are the principal features of Increased Cost of Compliance (ICC) coverage: Note all references are to the Standard Flood Insurance Policy Endorsement Number One.

  • ICC coverage responds to the enforcement of a State or local land use requirement to bring a flood-damaged structure into compliance with certain floodplain management standards during the rebuilding process.
  • The limit for increased cost of compliance (ICC) coverage is $30,000.
  • Only Standard Flood Insurance Policies (SFIPS) with Building coverage will have ICC coverage. Appurtenant structures are not eligible for ICC coverage. (See Exclusion 10.
  • The maximum amount collectible under the SFIP for both building coverage and Coverage A) and ICC (Coverage D) cannot exceed the maximum amount permitted under the Act, e.g., $250,000 for a single family dwelling.
  • ICC coverage will be available for new or renewal policies effective on or after June 1, 1997.
  • Only structures in Regular Program communities are eligible for [CC coverage. Structures insured under a Group Flood Insurance Policy or a condominium unit owner’s policy are NOT eligible for [CC coverage. (See Exclusions II and 12.)
  • Policies issued or renewed for structures while the community was in the Emergency Program are NOT eligible for [CC coverage. Once a community is converted to the Regular Program, these policies will be eligible for ICC coverage upon renewal with the payment of the ICC surcharge. (See Exclusion 1.)
  • No separate deductible applies to ICC coverage.
  • Only flood-damaged structures are eligible for the coverage.
  • Only those structures where flood damage meets the NFIP substantial or repetitive loss thresholds are eligible for ICC payments.
  • Activities eligible for ICC payments are: elevation, floodproofing, demolition, relocation, or any combination thereof.
  • ICC payments will be made to bring a structure into compliance with State or local elevation or floodproofing requirements for freeboard, i.e., an elevation above the base flood elevation. (See Eligibility, exception b.)
  • ICC payments will be made to bring a structure into compliance with State or local elevation requirements based on FEMA-issued advisory or preliminary base flood elevations which increase BFEs or change risk zones that add base flood elevations so long as such elevations are adopted by the State or community. (See Eligibility, exception a.)
  • ICC payments will be made to comply with NFIP requirements to elevate a structure in an unnumbered A zone to an elevation based on the best available elevation data. (See first paragraph after exception b of Eligibility.)
  • ICC payments will be limited to ONLY the cost to elevate a structure from the base flood elevation—applicable at the time of construction—to the current higher BFE IF the structure was NOT originally built in compliance AND IF no variance was obtained for the original construction.
  • ICC payments will be made to elevate a structure to the current BFE EVEN THOUGH the structure was not originally built in compliance so long as a variance was obtained for the original construction.
  • ICC payments will be made for demolition and any incremental costs to comply with elevation requirements for the structure during rebuilding at the same or another site.
  • All nonresidential structures are eligible for [CC payments in connection with floodproofing. Only residential structures with basements in communities that have been approved by the NFIP to floodproof basements in accordance with NFIP regulations at 44 CFR 60.6 (b) or (c) are eligible for ICC payments in connection with the floodproofing option. (See first paragraph.)
  • Repetitive loss structures are eligible for [CC payments when two conditions are met: (a) The community has adopted and is enforcing a cumulative substantial damage provision or repetitive loss provision in its floodplain management ordinance that requires action by the property owner; and (b) The property has a history of flood claims under the NFIP that satisfies the statutory definition of repetitive loss structure, i.e., two paid flood losses where the flood damage in a ten year period averages 25% of the structure’s value at the time of loss.
TASK:To adjust ICC claim for a policy rated post-FIRM with a negative elevation different when the structure was NOT built to the BFE in force at the time for construction.
A variance WAS issued. There HAS been an increase in BFE. ICC claim WILL BE ADJUSTED as usual. ICC payments will be made to elevate the structure to the new BFE.
A variance WAS issued. There has been NO increase in BFE. ICC claim WILL BE ADJUSTED as usual. ICC payments will be made to elevate the structure to the BFE.
A variance was NOTissued. There HAS been an increase in BFE. ICC claim WILL BE LIMITED to the cost of compliance to elevate the structure from the BFE at the time of construction to the current BFE.
A variance was NOTissued. There has been NO increase in BFE. ICC claim DENIED.
NOTE: If a structure WAS built to the BFE in force at the time of construction even though there is a negative elevation difference at the time of the ICC claim, the ICC claim will be paid to elevate to the CURRENT BFE.

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Appendix 1-8: ICC Claims Process

Thumbnail of ICC Claims Process diagram
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