North Carolina TarPamlico River Basin Plan

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North Carolina Tar-Pamlico River Basin Plan

• Final Scoping Meetings
• January 30 and 31, 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 be consistent with USGS DOQ
  tiling scheme

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Community Review and Due Process

• Preliminary FIRMs provided when Tar-Pamlico 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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Tar-Pamlico River Basin

• Extends from its headwaters in the north central
  Piedmont section of North Carolina to the
  Atlantic Ocean
  
• Most of the upstream portion (Tar River) is
  freshwater, whereas the downstream portion (the
  Pamlico River) is entirely estuarine
  
• Comprised of portions of 19 counties and 53
  municipalities

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Scoping Phase for Tar-Pamlico 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
• Two separate Final Scoping Meetings
• January 30th - Greenville, NC
• January 31st - Tarboro, NC
• Draft Tar-Pamlico 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 Meetings
  
• Watershed Concepts, the States Floodplain
  Mapping Contractor for the Tar-Pamlico River
  Basin, will develop proposals for the State
  
• Tar-Pamlico River Basin Plan will be finalized
  and distributed to impacted counties and
  communities
  
• Production phase will then begin

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North Carolina Tar-Pamlico River Basin Meeting

• QUESTIONS ON THE SCOPING PHASE
• ? ? ?

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Draft Tar-Pamlico 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
(contd)
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Riverine Areas to be Studied in Detail
(contd)
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Riverine Areas to be Studied in Detail
(contd)
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Riverine Areas to be Studied in Detail
(contd)
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Riverine Areas to be Studied in Detail
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Redelineation

• This method requires the following
• DEMs
• 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
• DEMs
• 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 Tar-Pamlico River Basin
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Schedule for FIRM Production
(contd)
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Schedule for FIRM Production
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Community Review and Due Process

• Preliminary FIRMs provided when Tar-Pamlico 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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North Carolina Tar-Pamlico River Basin Meeting

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