North Carolina Cape Fear River Basin Plan

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North Carolina Cape Fear River Basin Plan

• Final Scoping Meetings
• March 6, 7, and 8, 2001

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North CarolinaCooperating Technical State Flood
Mapping Program Overview
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Purposes of the NFIP

• 1. Make flood insuranceavailable
• 2. Identify floodplainareas and flood risk zones
• 3. Provide framework for a communitys floodplain
  management ordinances

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Importance of Updated Flood Hazard Information

• With up-to-date flood hazard data
• Map users can make prudent siting, design, and
  flood insurance purchase decisions
• Communities can administer sound floodplain
  management programs

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North Carolinas Flood Mapping Program

• Program established to implement the Cooperating
  Technical State (CTS) Partnership with FEMA,
  signed September 15, 2000
• Ownership and responsibility for Flood Insurance
  Rate Maps (FIRMs) delegatedto State

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Organization of the CTS Flood Mapping Program
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Why North Carolina Is Undertaking This Project

• States vulnerability to hurricanesand flooding
• 14 federally declared disasters since 1989
• Hurricane Floyd damages 3.5 billion
• 4,117 uninsured/under-insured homes destroyed as
  result of Hurricane Floyd
• Accurate, up-to-date flood hazard information
  crucial to protect livesand property

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Why North Carolina Is Undertaking This Project

• Hurricane Floyd revealed flood hazard data and
  map limitations
• Age of North Carolina FIRMS
• 55 at least 10 years old
• 75 at least 5 years old
• FEMAs mapping budget is finite
• North Carolina receives only one updatedflood
  study for one county per year
• Many counties and communities lack resources to
  take on this responsibility

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Benefits of North Carolinas CTS Program

• Current, accurate data for sound siting and
  design decisions
• Better floodplain management to reduce long-term
  flood losses
• Updated data to alert at-risk property owners of
  the need for flood insurance
• Faster, less expensive FIRM updates

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Program Components

• Developing flood hazard studies through community
  mapping needs analysis (Scoping)
• Acquiring high-resolution topographic data and
  accurate Digital Elevation Models (DEMs)
• Conducting engineering studies
• Generating countywide digital FIRMs (DFIRMs)
• Designing and implementing state-of-the-art,
  dynamic IT infrastructure
• Supporting real-time flood forecasting and
  inundation mapping capability

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Digital FIRMs
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Digital FIRMs

• Digital FIRMs will be produced in a countywide
  format
• Will depict all flood hazard data
• FIRM panels will probably be consistent with the
  State land records 10,000 by 10,000 tiling
  scheme

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Community Review and Due Process

• Preliminary FIRMs provided when Cape Fear River
  Basin Study is complete
• 90-day appeal period
• Preliminary Countywide FIRMs provided when
  adjacent basin studies are complete
• All appeals evaluated and resolved
• Final Effective FIRMs provided and made available
  by the State on its Information Management System

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Additional Benefits of the CTS Program

• Digital format to allow
• More efficient, precise flood risk determinations
• Geographic Information System (GIS) analysis and
  planning
• Online access 24 hours a day
• DEMs will be useful for almost any engineering or
  planning application

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Cape Fear River Basin

• Extends from its headwaters near Greensboro and
  High Point in the north central Piedmont region
  of North Carolina to the Atlantic Ocean near
  Wilmington and Cape Fear
• Largest river basin in North Carolina,
  encompassing an area of approximately 9,300
  square miles
• Encompasses all or parts of 29 counties and 110
  municipalities

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Scoping Phase for Cape Fear River Basin

• The Scoping Phase determines
• What areas are floodprone and need flood hazard
  data developed
• Determine appropriate technical method for
  developing up-to-date flood hazard data and
  establish priority level
• How flood hazard data will be presented on FIRMs

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Step 4 Final Scoping Meeting

• THIS IS WHERE WE ARE TODAY!
• All impacted counties and communities invited
• Three separate Final Scoping Meetings
• March 6th Haw River, NC
• March 7th - Fayetteville, NC
• March 8th Burgaw, NC
• Draft Cape Fear River Basin plan presented
• Provides final opportunity for input

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Step 5 Final Basin Plan

• Draft Basin Plan may be revised following the
  Final Scoping Meeting
• Greenhorne OMara, the States Floodplain
  Mapping Contractor for the Cape Fear River Basin,
  will develop proposals for the State
• Cape Fear River Basin Plan will be finalized and
  distributed to impacted counties and communities
• Production phase will then begin

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North Carolina Cape Fear River Basin Meeting

• QUESTIONS ON THE SCOPING PHASE
• ? ? ?

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Draft Cape Fear River Basin Plan

• Summarizes scoping phase
• Outlines how base maps and topography will be
  acquired
• Proposes engineering methods by which each
  flooding source reach will be studied
• Describes the process and schedule for completing
  the map production

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Detailed Study Riverine

• This method requires the following
• DEMs
• Field surveys
• Channel bathymetry
• Bridge/culvert opening geometry
• Channel and floodplain characteristics
• Detailed Hydrologic and Hydraulic Analyses
• 10, 2, 1, and 0.2 annual chance flood
  elevations and boundaries identified (Zone AE)
• Floodways delineated

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Riverine Areas to be Studied in Detail
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Riverine Areas to be Studied in Detail
(contd)
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Detailed Study Coastal

• This method produces the following
• Floodplain mapping for areas alongopen coast and
  embayments
• Designations as Zones AE or VE

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Coastal Areas to be Studied in Detail
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Redelineation

• This method requires the following
• Digital Elevation Data
• Effective FIS flood elevations

Proposed for all areas currently shown on
effective FIRM as Zone AE or VE and not being
restudied
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Approximate Study

• This method requires the following
• Digital Elevation Data
• Delineation of 1 annual chance floodplain
  boundaries using approximate methods
• Does not include collection/use of
  field-collected topographic data or
  bridge/culvert data

Proposed for all areas currently shown on
effective FIRM as Zone A and not being restudied
in detail.
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Use of Effective Information

• This method involves no new analyses or
  floodplain mapping
• Effective FIS and FIRM data are digitized and
  fitted to updated base map

This method is not anticipated to be used for any
communities in the Cape Fear River Basin
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Going Beyond the Minimum

• Communities are encourgaged to manage floodplain
  development according to standards that are more
  stringent than FEMA minimums.
• Benefits of adopting higher standards
• Reduced risk to lives and property, and
• Lowered flood insurance premiums, including
  possible Community Rating System discounts.

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Community Mapping Options

• Community-adopted higher standards can be
  supported by optional map features shown
  digitally in a separate GIS layer, or possibly
  printed on the FIRM, or both.
• Communities can have customized flood hazard
  data generated for their area through the NC
  Flood Mapping Program.

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Community Mapping Options (continued)

• Customized flood hazard data options
• 1 annual chance floodplains and elevations based
  on future land use conditions (in addition to
  existing conditions data),
• Wider floodways based on a reduced surcharge
  value (i.e., less than the 1-foot FEMA maximum),
  and

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Community Mapping Options (continued)

• Flood hazard data options (continued)
• Areas within a community-adopted freeboard
  contours (i.e., areas that would be inundated if
  floodwaters reached the freeboard level)

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Guidance for Communities

• The State will provide guidance to communties on
• Selecting higher standards options that meet
  community needs,
• Data the communities must provide (land use plan,
  etc.),
• Potential community cost sharing to cover
  increased mapping costs,

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Higher Standards (continued)

• State guidance (continued)
• Model Flood Hazard Damage Prevention ordinances
  that reflect enhanced floodplain management
  standards, and
• Outreach programs for citizens and businesses
  affected by newly mapped flood hazard areas or
  updated ordinances.

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Schedule for FIRM Production
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Schedule for FIRM Production
(contd)
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Schedule for FIRM Production
(contd)
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North Carolina Cape Fear River Basin Meeting

• QUESTIONS ON THE
• DRAFT BASIN PLAN
• ? ? ?