North Carolina North Carolina White Oak River Basin White Oak River Basin

PlanPlanDecember 19, 2000

North CarolinaNorth CarolinaCooperating Technical Cooperating Technical State Flood Mapping State Flood Mapping Program OverviewProgram Overview

Purposes of the NFIPPurposes of the NFIP

1. Make flood insuranceavailable

2. Identify floodplainareas and flood risk zones

3. Provide framework for a community’s floodplain management ordinances

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

Importance of Updated Importance of Updated Flood Hazard InformationFlood Hazard Information

North Carolina’s North Carolina’s Flood Mapping Flood Mapping

ProgramProgram 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

Why North Carolina Is Why North Carolina Is Undertaking This Undertaking This

ProjectProject State’s vulnerability to hurricanes

and 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

Why North Carolina Is Why North Carolina Is Undertaking This Undertaking This

ProjectProject 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

FEMA’s mapping budget is finite North Carolina receives only one updated

flood study for one county per year Many counties and communities lack

resources to take on this responsibility

Program Program ComponentsComponents

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

Digital FIRMDigital FIRM

Digital FIRM=

Flood DataBase + Topography +

Funding for this Funding for this Program Program

In August 2000, North Carolina General Assembly approved funding for first six river basins ($23 million)

FEMA has contributed $6 million, as well as in-kind professional services

North Carolina is also working with other Federal partners to secure additional funding

Benefits of North Benefits of North Carolina’s CTS Carolina’s CTS

ProgramProgram 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

Benefits of North Benefits of North Carolina’s CTS Carolina’s CTS

ProgramProgram 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

White Oak River White Oak River BasinBasin

Located in the southern coastal plainof North Carolina

Includes 4 separate river drainage systems (New, North, White Oak, Newport Rivers and tributaries)

Comprised of portions of 4 counties and 14 municipalities

Scoping Phase for Scoping Phase for White Oak River White Oak River

BasinBasinThe Scoping Phase determines: What areas are floodprone and

need flood hazard data developed What methods will be used to

generate flood hazard data How the data will be presented on

FIRMs

Scoping Phase for Scoping Phase for White Oak River White Oak River

BasinBasin Research/inventory all available

elevation, flood hazard, and digital base map data

Assess existing flood hazard data on effective FIRMs

Determine appropriate technical method for developing up-to-date flood hazard data and establish priority level

Five Steps of Scoping Phase

Step 1 — Initial Research Step 1 — Initial Research and Community and Community

CoordinationCoordination

State held “kickoff” meeting with county and local floodplain administrators

Obtained community mapping needs Effective Flood Insurance Study (FIS) and

FIRM information was researched Post-Hurricane Floyd data was evaluated Research and mapping needs were

entered into GIS-enabled scoping database

Step 2 — Initial Scoping Step 2 — Initial Scoping MeetingsMeetings

State held meetings with each county to present research results and discuss flood mapping needs

Input gathered from communities on proposed study priorities and analysis methods

Identified potential resources of local GIS base map data

Step 3 — Draft Basin PlanStep 3 — Draft Basin Plan

Plan for developing updated flood hazard data and countywide DFIRMs

Comprised of results from research and county and community input

Includes listing of flooding sources to be updated within the basin, technical methods, and projected schedule

Step 4 — Final Scoping Step 4 — Final Scoping MeetingMeeting

THIS IS WHERE WE ARE TODAY!

All impacted counties and communities invited

Draft White Oak River Basin plan presented

Provides final opportunity for input

Step 5 — Final Basin PlanStep 5 — Final Basin Plan

Draft Basin Plan will be revised following the Final Scoping Meeting

Watershed Concepts, Inc., will develop proposals for the State

White Oak River Basin Plan will be finalized and distributed to impacted counties and communities

Production phase will then begin

North Carolina North Carolina White Oak Basin MeetingWhite Oak Basin Meeting

QQUESTIONS ON THE UESTIONS ON THE SCOPING PHASESCOPING PHASE

? ? ?? ? ?

Draft White Oak Draft White Oak River Basin PlanRiver 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

Base MapsBase Maps

Countywide Digital FIRM Production will be based on the following: U.S. Geological Survey (USGS) Digital

Orthophoto Quadrangles (DOQs), based on 1998 Aerial Photography

Local GIS data for streams, political boundaries, and roads may be used to supplement the DOQs

Topographic DataTopographic Data

Will be acquired using airborne Light Detection and Ranging (LIDAR)

Will be acquired during the Winter2000-2001 flying season

Will produce an equivalent to a approximately 2-foot contour interval map in floodplains

Digital Elevation Models (DEMs) will be generated to be used for modeling

RecommendedRecommendedStudy AreasStudy Areas

Five study options: Detailed study (riverine) Detailed study (coastal) Redelineate using updated topographic

data Approximate study Use current effective information (not

selected for any areas)

Detailed Study — Detailed Study — RiverineRiverine

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

Areas to be StudiedAreas to be Studiedin Detailin Detail

Detailed Study — Detailed Study — CoastalCoastal

This method produces the following: Floodplain mapping for areas along

open coast and embayments Designations as Zones AE or VE

No detailed coastal studies are proposed

RedelineationRedelineation

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

Approximate StudyApproximate 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.

Use of Effective Use of Effective InformationInformation

This method involves no new analyses or floodplain mapping

Effective FIS and FIRM data is digitized and fitted to updated base map

This method is not anticipated to be used for any communities in the White Oak River Basin

Variations from Variations from Community-Identified Community-Identified

Needs & PrioritiesNeeds & Priorities

Necessary to deviate from community-identified needs and priorities due to: Conflicting needs and priorities

identifiedby contiguous communities sharing a flooding source

Less dense development In these instances, the State used a

quantitative ranking system to determine methods

Digital FIRMsDigital 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

Schedule for FIRM Schedule for FIRM ProductionProduction

Community Review and Community Review and Due ProcessDue Process

Preliminary FIRMs provided when White Oak 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

Community Review and Community Review and Due ProcessDue Process

Many counties and communities will need to update their floodplain management ordinances

Communities will be given a 6-month period to do so

NCDEM and FEMA will coordinate this effort with affected communities

North Carolina North Carolina White Oak Basin MeetingWhite Oak Basin Meeting

QQUESTIONS ON THE UESTIONS ON THE

DRAFT BASIN PLANDRAFT BASIN PLAN

? ? ?? ? ?