NORTH CAROLINA FLOODPLAIN MAPPING PROGRAM COOPERATING TECHNICAL STATE

Transcription

1 NORTH CAROLINA FLOODPLAIN MAPPING PROGRAM COOPERATING TECHNICAL STATE FINAL BASIN PLAN WATAUGA RIVER BASIN Prepared by the: State of North Carolina and the Federal Emergency Management Agency December 21, 2006

2 TABLE OF CONTENTS PAGE Contact Information... iv Abbreviations and Acronyms... v I. Introduction...1 Why the State of North Carolina Created the Floodplain Mapping Program... 1 Components of the North Carolina Floodplain Mapping Program...2 Floodplain Mapping Program Funding and Work Plan...3 Program Benefits...3 II. Watauga River Basin Description...5 III. IV. Scoping Phase for the Watauga River Basin...8 Step 1 Initial Research and Community Coordination Step 2 Initial Scoping Meetings Step 3 Draft Basin Plan Step 4 Final Scoping Meetings Step 5 Final Basin Plan Elevation and Flood Data Development and Digital FIRM Production for the Watauga River Basin Base Map Topographic Data Flood Hazard Data Detailed Study Riverine Limited Detailed Study Redelineation Use of Effective Information Variations from Community-Identified Needs and Priorities Digital FIRMs V. Community Review and Due Process Date: December 21, 2006 Page i

3 TABLE OF CONTENTS PAGE List of Figures Figure 1. Total Flood Claims and Repetitive Loss Policies...1 Figure 2. Three Phases of Development and Production...3 Figure 3. Phases of the North Carolina State-wide Floodplain Mapping Program. 3 Figure 4. Watauga River Basin Vicinity Map...5 Figure 5. Watauga General Basin Map...7 Figure 6. Process for Scoping the Watauga River Basin Figure 7. Components of a Digital FIRM List of Tables Table 1. Community Information...8 Table 2a. USGS Gage Information Detailed Studied Flooding Sources Table 2b. USGS Gage Information Approximate Zone A Flooding Sources Table 3. Initial Scoping Meetings for the Watauga River Basin Table 4. Summary of Riverine Flooding Sources to be Studied in Detail Table 5. Summary of Technical Methods for the Watauga River Basin Table 6. Summary of Digital FIRMs for the Watauga River Basin Appendices Appendix A. Attendance Sheets from Initial Scoping Meetings...A-1 Appendix B. Summaries of Community-Identified Flood Mapping Needs...B-1 Appendix C. Attendance Sheet(s) from Final Scoping Meeting(s)...C-1 Appendix D. Summary of Flooding Sources to be Studied by Limited Detailed Methods.....D-1 Appendix E. Summary of Flooding Sources to be Studied by Redelineation...E-1 Appendix F. Summary of Variations from Community-Identified Needs and Priorities.F-1 Date: December 21, 2006 Page ii

4 TABLE OF CONTENTS A. Attachments 1. Community Recommendations Watauga River Basin A. County, North Carolina B. Watauga County, North Carolina 2. Final Basin Plan Watauga River Basin A. County, North Carolina B. Watauga County, North Carolina Date: December 21, 2006 Page iii

5 CONTACT INFORMATION Questions or comments about this Basin Plan can be directed to: Randy Mundt, Community Development Planner North Carolina Floodplain Mapping Program (919) x119 or Questions about the National Flood Insurance Program (NFIP) and NFIP mapping can be directed to the Federal Emergency Management Agency s Map Assistance Center toll free information line at FEMA MAP ( ) or FEMAMapSpecialist@mapmodteam.com. Date: December 21, 2006 Page iv

6 ABBREVIATIONS AND ACRONYMS The following abbreviations and/or acronyms are used throughout this Basin Plan. Abbreviation/Acronym Description BFE Base Flood Elevation CGIA Center for Geographic Information and Analysis CTS DEMs Digital Elevation Models DFIRM Digital Flood Insurance Rate Map DOQs Digital Orthophoto Quadrangles FEMA Federal Emergency Management Agency FEMA-MCC FEMA s Mapping Coordination Contractor (Dewberry) FIS Flood Insurance Study FIRM Flood Insurance Rate Map FMIS Floodplain Mapping Information System GIS Geographic Information Systems LIDAR Light Detection and Ranging MENCA Mapping and Engineering Needs Community Assessment NAVD 88 North American Vertical Datum of 1988 NCEM North Carolina Division of Emergency Management NCDENR North Carolina Department of Environment and Natural Resources NCFMP North Carolina Floodplain Mapping Program NFIP National Flood Insurance Program NGVD 29 National Geodetic Vertical Datum of 1929 TIN Triangulated Irregular Network USGS U. S. Geological Survey UT Unnamed Tributary Date: December 21, 2006 Page v

7 I. INTRODUCTION The State of North Carolina, through the Federal Emergency Management Agency s (FEMA s) Cooperating Technical Community partnership initiative, has been designated as the nation s first (CTS). As a CTS, the State has assumed primary ownership and responsibility of the National Flood Insurance Program s (NFIP) Flood Insurance Rate Maps (FIRMs) for all North Carolina communities. This role has traditionally been fulfilled by FEMA. North Carolina faces extreme hazards and consequence from hurricanes and flooding. Since 1989, there have been at least 21 federally declared disasters in North Carolina. Damages from Hurricane Floyd alone have reached $3.5 billion. As a result of Hurricane Floyd, 4,117 uninsured and under-insured homes were destroyed. Figure 1 below shows the number of flood claims and repetitive loss policies in the Watauga River Basin between the years of 1978 and The State s vulnerability to hurricanes and flooding make it crucial that communities and property owners have accurate, up-todate information about the flood risk. The updated digital Flood Insurance Rate Maps (DFIRMs) produced through this Program will help to protect the lives and property, and contribute to the general well being, of North Carolina citizens. County No. of Policies / Claims since 1978 Repetitive Loss Structures / Claims 141 / 84 7 / 15 Watauga 274 / 95 5 / 13 Figure 1. Total Flood Claims and Repetitive Loss Policies Why the State of North Carolina Created the Floodplain Mapping Program There are several reasons why the State has initiated this Program; these include the following: Approximately 55% of North Carolina FIRMs were at least 10 years old. Approximately 75% of North Carolina FIRMs were at least 5 years old. FEMA s mapping budget is finite; on average, North Carolina received only one updated flood study for one county per year. Many counties and communities have indicated that they do not have the resources to take on this responsibility. Date: December 21, 2006 Page 1

8 Components of the North Carolina Floodplain Mapping Program The North Carolina Floodplain Mapping Program involves the following: Acquisition of high-resolution topographic data and development of accurate Digital Elevation Maps (DEMs). Development of up-to-date, accurate flood hazard data and floodplain mapping. Production of seamless digital FIRM coverage state-wide: - Digital FIRMs will be produced on a state-wide basis where all counties and incorporated communities are seamlessly shown across one set of state maps. - Digital Orthophoto Quadrangles (DOQs), produced in partnership by the State of North Carolina and the U.S. Geological Survey (USGS), will be used as the primary base map. In areas where there is a locally produced base map that is more current or accurate than the DOQs, the locally developed map may be used to supplement or in place of the DOQs as the base. - Flood Elevations on the DFIRMs will be converted to the North American Vertical Datum of 1988 (NAVD 88). The North Carolina Floodplain Mapping Program (NCFMP), administratively located in the North Carolina Division of Emergency Management (NCEM) oversees and manages the Program. The NCFMP will work closely with several other state agency partners (North Carolina Geodetic Survey [NCGS], Center for Geographic Information and Analysis [CGIA], and the Floodplain Management Branch) to ensure quality map production. In the production of the Basin Plan, the NCFMP has worked in close cooperation with the Floodplain Management Branch of the NCEM to ensure that all flood hazards and NFIP issues are addressed. Additionally, after the updated flood data and maps are produced, the NCFMP coordinates with Floodplain Management to conduct training and outreach to assist communities in utilizing the new data and maps to implement floodplain management and hazard mitigation activities. The NCFMP has also implemented a state-of-the-art, dynamic Floodplain Mapping Information System (FMIS) to analyze, maintain, and archive maps and associated flood hazard data. The FMIS also serves to present and distribute the mapping data and associated reports to the public via the Internet without the user needing to have sophisticated Geographic Information System (GIS) software. An additional component of the Program is a real-time flood forecasting and inundation mapping capability. The North Carolina Flood Warning System is currently being piloted in the Tar-Pamlico and Neuse River Basins. The development of topographic and flood data and production of state-wide digital FIRM panels will have three phases (Figure 2): (1) scoping, (2) flood map production, and (3) Community Review and Due Process (post-preliminary process). Date: December 21, 2006 Page 2

9 Scoping Flood Map Production Community Review and Due Process Figure 2. Three Phases of Development and Production Flood Mapping Program Funding and Work Plan In August 2000, the North Carolina General Assembly allocated $42.8 million to the Floodplain Mapping Program. FEMA has contributed an additional $30.65 million toward the Program as well as in-kind contribution of engineering, mapping, and program management services. The State has also worked with other Federal partners to secure additional needed funding. Based on the General Assembly s directive, work began on the six eastern river basins as shown in Figure 3 (Phase I Cape Fear, Lumber, Neuse, Pasquotank, Tar-Pamlico, and White Oak). Work was initiated on six additional river basins in 2003 (Phase II Chowan, Roanoke, Yadkin, Catawba, Watauga, and New). Work on the remaining five basins (Phase III Broad, French Broad, Little Tennessee, Hiawassee, and Savannah) started in the summer of 2005 and the General Assembly of North Carolina provided an additional $10 million. Figure 3. Phases of the North Carolina Floodplain Mapping Program Program Benefits The North Carolina State-wide Floodplain Mapping Program will provide many benefits to North Carolina communities, property owners, and citizens. These include: The updated flood hazard data will provide current, accurate information for North Carolina communities and property owners to make safe siting and design Date: December 21, 2006 Page 3

10 decisions when rebuilding from flooding disasters, building new structures and infrastructure, and retrofitting existing structures. The use of the updated data by communities for floodplain management will dramatically reduce long-term flood losses to the State of North Carolina, its communities, and its citizens. Updated flood hazard data will alert those at risk of flooding of the need to purchase flood insurance protection. It will be faster and more cost effective to update digital FIRMs. Current, updated base maps and the digital format of the FIRMs will allow users to make more efficient, precise flood risk determinations. The resultant digital FIRMs will be the official NFIP maps; these digital FIRMs will also be used by communities for floodplain management purposes. The digital format of the digital FIRMs will allow use with GIS for analysis and planning. The digital Floodplain Mapping Information System (FMIS) will allow online access to all map users 24 hours a day without requiring sophisticated GIS software. The DEMs being developed will be useful for almost any engineering or planning application, such as site design, storm-water management, transportation planning and design, and spill response. This report summarizes and provides details about the scoping phase that was completed for the Watauga River Basin and how the results of this scoping effort were used to develop a plan for developing updated flood data and state-wide digital FIRMs for counties and communities located within the Watauga River Basin. This report also describes the process and schedule for completing the map production and community review phases. Date: December 21, 2006 Page 4

11 II. Watauga River Basin Description The Watauga River Basin, is located within the Blue Ridge Province of the Appalachian Mountains of western North Carolina. This basin is nestled between the French Broad and Catawba River Basins to the south and the New River basin to the north. The watershed drains north to northwest from North Carolina to Tennessee. Figure 4. Watauga River Basin Vicinity Map The Watauga River Basin is composed of the headwaters and tributaries of the Elk River and the Watauga River. The Elk River, the principal tributary of the Watauga River, and the Watauga River flow into Watauga Lake in Tennessee. The Watauga River and Elk River are headwater tributaries of the Holston River system and flow northwest from North Carolina to Tennessee and has approximately 303 streams. These waters flow into the Tennessee River and eventually into the Mississippi River and the Gulf of Mexico. Elk Falls, located in County on the Elk River, is 65 feet in height and is known to have one of the largest and deepest plunge pools of any waterfall in the State. This is a well known swimming, sunbathing and gathering place for students from the local colleges. Date: December 21, 2006 Page 5

12 The basin is the second smallest in the state, encompassing only 184 square miles of watershed. The basin contains approximately 270 miles of freshwater streams and rivers. The upper portion of the Watauga River and most tributaries support a good trout fishery; this intergrades with a cool-water fishery (smallmouth bass) in the middle and lower section of the river. Most tributaries are trout streams, although sedimentation may reduce the quality of the fisheries in some of these streams. The basin contains approximately 283 miles of freshwater streams and rivers. The topography of the Watauga River Basin is mountainous. Steep slopes limit developable land for construction and agricultural uses, which are concentrated in the valleys. Roads are commonly situated along the flooding sources. According to the United States Department of Agriculture Natural Resources Conservation Service (USDA-NRCS) National Resources Inventory of 1992 the land cover is approximately 56% forested, 24% pasture, 8% urban, 8% other (rural transportation & associated rights-of-way, small water areas [water bodies less than 40 acres in size and streams less than ½ mile wide] and census waters [large water bodies consisting of lakes and estuaries greater than 40 acres and rivers greater than ½ mile in width] and 4% uncultivated cropland or agriculture. Land cover in the basin is dominated by forest and pasture lands. Between 1982 and 1997, land-use identification shows urban and developed land increased by 8,200 acres and forestlands decreased by 8,000 acres. The Watauga River Basin is home to many natural resources including various rock types, unusual wetlands, and a range of elevations. Two of the more significant sites n the Southern Appalachian Mountains are Grandfather Mountain and Roan Mountain Massif, where rare plants and animals dwell. This basin contains several high quality mountain bogs. Bogs are defined as wet spongy ground areas or poorly drained, usually acid, areas rich in accumulated plant material, frequently surrounding a body of open water, and frequently having a unique flora and fauna. Mountain bogs are saturated with water most of the year and may have thick layers of moss underlain by peat moss and are acidic. These bogs are often small and do not make up a significant portion of the landscape; however they support many atypical plants and animals, including bog turtles. Unfortunately, about 90% of mountain bogs in North Carolina have been destroyed. Date: December 21, 2006 Page 6

13 Figure 5. Watauga General Basin Map The economy of the Watauga River Basin is largely supported by the presence of a major state university (Appalachian State University), thriving year-round tourism, broad-based retail, agricultural and forest products, and transportation-related businesses. Watauga County has one of the lowest annual unemployment rates in the State and 45% of the properties are absentee-owned. One-third of all new building permits in the county are attributed to seasonal housing. The Town of Boone and Watauga County are home to at least 35 manufacturing firms which employ up to 300 Date: December 21, 2006 Page 7

14 employees per firm. These home-grown companies manufacture and distribute items such as: leather products, wood furniture components, indoor metal furniture, candies and mints, log homes, and specialty paint systems. County, too, has a low unemployment rate (4.3% as recorded in 2003) and is an agricultural-based county where over 80% of the lands are farmed. 11% of the County residents work in manufacturing, while 25% are professionals, 16% work in production, and 20% work in sales. Flooding in the Watauga River Basin occurs as a result of poorly constructed roads and flash-flooding caused by the steep terrain. and Watauga Counties are partially located within the Watauga River Basin and are summarized in Table 1 below. Community Name County Participation Status Date of Current NFIP Map AVERY COUNTY AVERY Regular/Participating 9/28/1990 BANNER ELK, TOWN OF AVERY Regular/Participating 1/15/1988 ELK PARK, TOWN OF AVERY Regular/Participating 4/15/1986 LINVILLE AVERY Non-Participating Not Mapped CROSSNORE AVERY Regular/Participating 8/19/1986 SUGAR MOUNTAIN AVERY Non-Participating Not Mapped NEWLAND AVERY Regular/Participating 12/4/1984 GRANDFATHER VILLAGE AVERY Non-Participating Not Mapped BLOWING ROCK WATAUGA Regular/Participating 1/17/1997 BEECH MOUNTAIN, TOWN OF WATAUGA Regular/Participating 1/17/1997 BOONE, TOWN OF WATAUGA Regular/Participating 1/17/1997 SEVEN DEVILS, TOWN OF WATAUGA Regular/Participating 1/17/1997 WATAUGA COUNTY WATAUGA Regular/Participating 9/21/1998 Table 1. Community Information III. SCOPING PHASE FOR THE WATAUGA RIVER BASIN The State worked closely with FEMA and Dewberry to complete the scoping phase for the Watauga River Basin counties and communities in the winter of Stated simply, scoping is determining what areas are floodprone and need to have flood hazard data developed, what methods will be used to generate that hazard data, and how the data will be presented on the DFIRMs. For the Watauga River Basin, the comprehensive scoping phase entailed: Date: December 21, 2006 Page 8

15 Researching and inventorying available elevation, flood hazard, and digital base map data that may be useful for preparing updated digital FIRMs; Assessing existing flood hazard data (for example: flood elevation profiles, floodplain boundaries, floodways, coastal hazard zones) on effective FIRMs for adequacy; Providing outreach to, and receiving input from, counties and communities regarding their needs for updated DFIRMs; Identifying data that needs to be developed or acquired, such as digital base maps, DEMs, or field surveys of stream channels, hydraulic structures; Determining the proposed scales and paneling scheme for state-wide digital FIRM production; and Developing a schedule for completion of updated flood hazard data and digital FIRM production. For flooding sources within the basin, the flood hazard data from the effective FIRMs was assessed for adequacy in consultation with the impacted counties and communities. For areas where the existing flood hazard data was deemed to be inadequate or outdated, a priority level was established and the most appropriate method of developing updated data was selected based on the: Type and extent of man-made and natural changes within the floodplain and/or watershed; Quality of data available; and Existing and/or proposed levels of development affected by the flooding source. The process followed for completing the scoping is shown in Figure 6 and is described further below. Date: December 21, 2006 Page 9

16 Scoping Flood Map Production Step 1 Step 2 Step 3 Step 4 Step 5 Initial Research & Community Coordination Initial Scoping Meeting Draft Basin Plan Final Scoping Meeting Revise Draft Basin Plan Technical & Cost Proposals for Contractors Finalize Basin Plan Figure 6. Process for Scoping the Watauga River Basin Distribute Final Basin Plan to Communities Analysis and Mapping Date: December 21, 2006 Page 10

17 Step 1 Initial Research and Community Coordination The State held two central kickoff meetings in 2003 with county and community floodplain administrators, engineers, and planners on June 30, 2003 in Weldon and on July 8, 2003 in Statesville. The objectives of the meetings were to overview the State s CTS Agreement with FEMA and the North Carolina Floodplain Mapping Program, inform the floodplain administrators of the process that will be followed to develop updated mapping, and encourage them to be an active participant in the process. A questionnaire regarding the communities mapping needs was mailed prior to the meeting and distributed to those community representatives in attendance. This questionnaire contained pointed questions designed to help each community systematically ascertain its flood mapping needs. The county and community officials were encouraged to complete the questionnaire and submit it either digitally via or in a hardcopy delivered by the US Postal Service. Technical support was available for completion of the questionnaire through the State. Completed questionnaires were received by the State from the following counties and communities in the Watauga River Basin: Elk Park and Watauga County Additionally, the State completed research of community mapping needs as per its September 2000 Cooperating Technical Community agreement with FEMA, Assessment of Community Mapping Needs. Further, FEMA and Dewberry conducted research of effective Flood Insurance Study (FIS) and FIRM information and other relevant data available for each community in the FEMA Flood Mapping Archives and FEMA s Mapping Needs Update Support System database. This database contains information on community mapping needs collected over the past few years through community surveys. Up-to-date analyses for 5 stream gages located in the Watauga River Basin were obtained from the USGS for Detailed and Approximate Zone A studied flooding sources. The revised gage analyses were compared with effective FIRM information to determine the need for restudy of the flooding sources on which these gages are located. As part of this assessment, the 1% annual chance (100-year) discharge and 1% annual chance water-surface elevation were compared. Tables 2a and 2b outline this information for 5 stream gages in the Watauga River Basin. Date: December 21, 2006 Page 11

18 Table 2a. USGS Gage Information USGS Detailed Studied Flooding Sources 100-year Discharge (cfs) 100-year WSEL (ft) Gage Flooding Source Effective Gage Effective Gage Cove Creek 5,200 5,722 2,684 N/A Watauga River 36,051 39,160 2,632 2,634 N/A not applicable because stream is currently not studied by detailed methods *All elevations are referenced to the North American Vertical Datum of 1988 (NAVD 88) USGS Gage Table 2b. USGS Gage Information Approximate Zone A Flooding Sources 100-year Discharge (cfs) 100-year Elevation (NGVD) Effective Zone Flooding Source Effective Gage Zone A Elk River 76,510 N/A Zone A Peavine Branch 50 N/A Zone A Elk River 20,380 2,825 Zone A N/A not applicable because stream is currently not studied by detailed methods *All elevations are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29) The results of the initial research and responses to the community questionnaires were entered into a GIS-enabled scoping database: Mapping and Engineering Needs Community Assessment (MENCA). This database was used to generate Initial Scoping Projects for each community; these projects were used to conduct the Initial Scoping Meetings (Step 2). Step 2 Initial Scoping Meetings The State held meetings in each county in the Watauga River Basin to present the results of the initial research to the county and its communities and to discuss their flood mapping needs. Elected officials, planners, floodplain administrators, emergency managers, engineers, surveyors and GIS staff were invited from the county and each incorporated community, including those communities that do not participate in the NFIP. The meetings were held at the County Seat or other readily accessible locations. FEMA and Dewberry staff attended to provide program and technical support during the meetings. NCEM Floodplain Management Branch staff attended the meetings to exchange contact information with community Floodplain Administrators, establish contact with non-participating communities, and distribute copies of the current North Carolina model Flood Damage Prevention Ordinance. Table 3 summarizes the initial Date: December 21, 2006 Page 12

19 scoping meeting dates with each community. Meeting attendance sheets are included as Appendix A. Please note that portions of some counties in the Watauga River Basin are contained in other river basins. The initial scoping meetings were conducted on a county-wide basis and covered all areas of each county and community in the county irrespective of the basin. Table 3 contains a list of communities with the location and date of initial scoping meetings held for each community. Only those communities located entirely or partially within the Watauga River Basin are listed in Table 3. Table 3. Initial Scoping Meetings for the Watauga River Basin Community Meeting Location Meeting Date (s) County Banner Elk, Elk Park, Village of Sugar Mountain, County Watauga County Seven Devils, Blowing Rock, Boone, Watauga County 175 Linville Street Newland, NC 971 West King Street Boone, NC November 20, 2003 November 19, 2003 At the initial scoping meetings, the State, NCEM Floodplain Management Branch, and Dewberry representatives met individually, or in groups, with the county and its incorporated communities representatives to: Provide a brief overview of the Floodplain Mapping Program purpose, objectives, and goals; Review the research results for each community using the Initial Scoping Package; Discuss the community s mapping needs and response to the questionnaire; and Identify available local data such as base maps, topographic data, ongoing studies, etc. In assessing the communities flood mapping needs, emphasis was placed on: of future development; New or proposed crossings, encroachments, and flood controls; Historically flooded areas; Out-of-date or inadequate data on current FIRMs; Existing data mismatches with contiguous communities; and Out-of-date FEMA analyses (detailed or approximate). For flooding sources identified in the meeting as having a flood mapping need, the community was asked to provide input on proposed study priorities and analysis methods. Date: December 21, 2006 Page 13

20 Appendix B contains tables summarizing the community-identified flood mapping needs, suggested type of study, and priorities for each community within the Watauga River Basin. Attachments 1A and 1B depict these community-identified needs and priorities. Also, as part of the initial scoping effort, CGIA met with county GIS staff to inventory the availability of local GIS data to identify potential base map data resources for the Floodplain Mapping Program. Information collected from the survey form was entered into MENCA for Elk Park in County and Watauga County for the Watauga Basin. Step 3 Draft Basin Plan Based on the results of the Initial Scoping Meetings, the State synthesized the research and the community input. These results were used to develop the Draft Basin Plan for developing updated flood hazard data for the basin and for producing state-wide DFIRM panels for the affected counties and communities within the Watauga River Basin. Section IV of the Draft Basin Plan included a list of flooding sources to be updated within the basin, including the technical method of update (detailed, limited detailed and redelineation) and reach limits and stream miles to be updated. Section IV also included a comprehensive list of counties for which state-wide DFIRM panels will be produced including digital base map source to be used and proposed DFIRM paneling and tiling scheme. Lastly, Section IV also included a projected schedule for completing the basin studies and state-wide preliminary DFIRMs. Step 4 Final Scoping Meetings The draft Watauga River Basin Plan was sent to & Watauga Counties and the communities and posted on the State s website on March 10, Subsequently, the State held Final Scoping meetings for the Watauga River Basin counties and communities. The communities Chief Elected Officer, Floodplain Administrators, Planners, Engineers, GIS staff, Building and Zoning Officials were invited from each county and incorporated community in the basin to the Final Scoping Meetings. The objective of the Final Scoping Meeting is for the State to overview the Draft Basin Plan, including the proposed scope, schedule for the project, and provide an opportunity for additional county and community input or suggested changes to the Draft Basin Plan. Individual meetings, for and Watauga Counties, were scheduled for community leaders to meet with representatives from the State and Dewberry. This Final Basin Plan summarizes the comments and/or feedback received during the Final Scoping Meetings and includes the Final Scoping Meeting Attendance Sheets in Appendix C. Date: December 21, 2006 Page 14

21 Step 5 Final Basin Plan After the Final Scoping Meetings were held, the Draft Basin Plan was revised, as necessary, to produce this Final Basin Plan. This Final Basin Plan contains specific information regarding comments that were received and how the Draft Basin Plan was revised and why. The State then requested that its Flood Mapping Contractor prepare a technical and cost proposal to execute the components of the revised draft Watauga River Basin Plan. After negotiations between the State and the Flood Mapping Contractor, if the cost estimate indicates that the Basin Plan can be executed within the State s available budget for the Watauga River Basin, the Basin Plan will be finalized. However, if the negotiated cost estimate indicates that the Basin Plan cannot be executed within the State s available budget, the State may have to modify the scope of the project. This was not the case with the Watauga Basin Plan. Once the Watauga River Basin Plan is finalized, the Final Basin Plan will be posted on the State website, with a description and explanation of any changes made from the Draft Basin Plan for the public to view and download. Date: December 21, 2006 Page 15

22 IV. ELEVATION AND FLOOD DATA DEVELOPMENT AND DIGITAL FIRM PRODUCTION FOR THE WATAUGA RIVER BASIN The State s flood mapping contractor will develop digital elevation data, conduct engineering flood hazard analyses, and prepare floodplain delineations for the flooding sources in the Watauga River Basin and produce state-wide preliminary DFIRMs for the affected communities within the Watauga River Basin. Figure 6 shows how the base map, topographic data, and flood data will be used to build a DFIRM. Each component is discussed further in the following sections. + + Base Topography Flood Data = Digital FIRM Figure 7. Components of a Digital FIRM Base Map Locally produced digital orthophotography will be used as the base map for state-wide DFIRM production, provided that it meets FEMA s base map standards. If local imagery is not available, the U.S. Geological Survey (USGS) Digital Orthophoto Quadrangles (DOQs), based on 1998 aerial photography, will be used. The base maps will be supplemented with stream and river centerlines, shoreline, political boundaries, and road name data from other sources; this may include locally available GIS data. The specific local GIS data to be used to supplement the DOQs will be determined on completion and assessment of the CGIA s GIS surveys as discussed in Section III of this Final Basin Plan. Topographic Data Watershed Concepts, under contract with the State, acquired digital topographic data of the Watauga River Basin using airborne Light Detection and Ranging (LIDAR). This LIDAR data was acquired during the Spring flying season. The topographic data satisfies a vertical root-mean-square error (RMSE) accuracy standard of ±25 cm (±1.8) feet accuracy at the 95% confidence limit (or roughly equivalent to a 2.2 foot contour interval map) in floodplain areas. All elevations are Date: December 21, 2006 Page 16

23 referenced to the NAVD 88 and reflect orthometric heights. Variably spaced, bare-earth digital topographic data in ASCII point file format is combined with imagery (either flown concurrently with the LIDAR data or using existing digital orthophotos) to establish a Triangulated Irregular Network (TIN) to include selected breaklines used for hydraulic modeling. Furthermore, uniformly spaced Digital Elevation Models (DEMs), with 20 ft. x 20 ft. or 50 ft. x 50 ft. post spacing, are generated in multiple file formats. These topographic data will be primarily used for floodplain modeling and mapping for counties and communities in the Watauga River Basin (described below). However, the data will also be useful for other State and county engineering and planning applications using ARC/INFO and other GIS software and will be available through the State s online Information Management System described earlier in this plan. It is planned for these data to be available online in the fall of Flood Hazard Data In developing flood hazard data for each of the flooding sources in the Watauga River Basin, the State s Flood Mapping Contractor will utilize one of four options available. These are described below. All flood elevations will be referenced to the NAVD 88. All analyses and mapping will comply with FEMA s regulations, guidelines, and specifications for NFIP mapping. 1. Detailed Study Riverine This method entails using the TINs, supplements them with field surveys for channel bathymetry, bridge/culvert opening geometry, and channel and floodplain characteristics, to conduct fully detailed hydrologic and hydraulic analyses and floodplain mapping. This will include analyses of the 10%, 2%, 1%, and 0.2% annual chance flood peak discharges, water-surface elevations, profiles, and determination of a floodway. Riverine areas studied in detail will be designated as Zone AE on the updated digital FIRMs. Flood profiles and base flood elevations will be referenced to NAVD 88. Table 4 summarizes the riverine flooding sources and reach descriptions within the Watauga River Basin that will be studied using detailed methods. The estimated number of hydraulic structures is an approximation of the number of culverts, bridges, dams, and weirs along the reach to be studied in detail. These estimates were made based on the number of major road crossings using CGIA data and from the flood profiles in the current FIS report. Attachments 2A and 2B depict the specific reaches to be studied in detail. Date: December 21, 2006 Page 17

24 Table 4. Summary of Riverine Flooding Sources to be Studied in Detail Municipality County Flooding Source Downstream Limit Upstream Limit ; Town of Banner Elk ; Town of Banner Elk Watauga Watauga Elk River Horse Bottom Creek Shawneehaw Creek Sugar Creek Whitehead Creek Hanging Rock Creek Brushy Fork Laurel Fork Approximately 500 feet upstream of Elk River Parkway At the confluence with Hanging Rock Creek At the confluence with Elk Creek At the confluence with Elk River At the confluence with Elk River At the confluence with Elk River Approximately 600 feet downstream of State Hwy 421 At the confluence with Watauga River At the confluence of Sugar Creek Just downstream of Guignard Lane Approximately 150 feet upstream of Villa Cas Ave Approximately 0.40 mile upstream of Hardee s Lane Approximately 0.5 mile upstream of Chime Hill Drive Approximately 105 feet downstream of Dobbins Road (SR 1337) Approximately 675 feet upstream of Adams Cemetery Road (SR 1375) Approximately 350 feet upstream of George Wilson Road (SR 1105) Approx. Reach Length (miles) Estimated Number of Hydraulic Structures Date: December 21, 2006 Page 18

25 Table 4. Summary of Riverine Flooding Sources to be Studied in Detail (continued) Municipality County Flooding Source Downstream Limit Upstream Limit Watauga Watauga River NC/Tennessee Border At the Watauga/ County boundary Approx. Reach Length (miles) Estimated Number of Hydraulic Structures TOTAL Date: December 21, 2006 Page 19

26 2. Limited Detailed Study This method entails using the TINs being produced as part of the North Carolina Floodplain Mapping Program, without adding field-surveyed bathymetric or bridge/culvert opening geometric data, to conduct hydrologic and hydraulic analyses. In addition, this method does not include field surveys that determine specifics on channel and floodplain characteristics. However, bridge and culvert opening data from North Carolina Department of Transportation maintenance records is incorporated into the hydraulic analysis models. Limited detailed study will result in the delineation of the 1% annual chance floodplain boundaries and base flood elevations. These will be designated as Zone AE on the newly generated DFIRMs. Limited detailed study will also determine widths of the non-encroachment area at all studied cross sections. The nonencroachment widths given at modeled cross sections can be used by communities to enforce floodplain management ordinances that meet the requirement defined in 44 CFR 60.3(c)(10). This information will be provided in the Flood Insurance Study report to facilitate local floodplain management. The limited detailed study is a buildable product with a supporting engineering model that can be upgraded to full detailed study at a later date by adding field-surveyed river or stream channel and bridge/culvert opening geometric data. All flooding sources currently designated as Zone A on the effective FIRMs that are not being studied by detailed study methods will be reanalyzed using this limited detailed study method. In most cases, currently unmapped areas identified by communities as being a priority will be studied by the limited detailed study method unless they are otherwise being studied by detailed methods. Attachments 2A and 2B depict the specific reaches to be studied using limited detailed methods. Additionally, limited detailed study will be considered for unmapped flooding sources, with an emphasis on those in developed areas with a drainage area larger than 1-square mile. However, some floodprone areas with lesser drainage areas may also be mapped based on known hazards, level of development, and community-identified needs. Appendix D summarizes the flooding sources and descriptions within the Watauga Basin that will be studied using limited detailed methods. 3. Redelineation This method involves no new analyses; rather, the effective FIS and FIRM data will be fitted to the updated base map using the new LIDAR-derived topographic data. Floodways and cross section locations are digitized from the effective FIRMs and Flood Boundary and Floodway Map. Flood profiles and base flood elevations are converted from NGVD 29 to NAVD 88. Date: December 21, 2006 Page 20

27 where this technique is used will be designated as Zone AE on the updated DFIRMs. This technique is useful for riverine, lacustrine, and coastal flooding sources where the effective FIS engineering analyses are adequate but the topographic data used to delineate the floodplain boundaries is not sufficiently detailed or up-to-date. The redelineation method will be used for all flooding sources within the Watauga River Basin that are currently studied in detail on current FIRMs and that are not being restudied in detail as part of this Basin Plan. Appendix E summarizes the flooding sources and descriptions within the Watauga Basin that will be redelineated. 4. Use of Effective Information This method involves no new analyses or floodplain mapping; rather, the effective FIS and FIRM data will be digitized as is and fitted to the updated DFIRM. Use of this method is normally limited to areas of known flooding not associated with a coastal or riverine flooding source (isolated ponding and swamp areas, for example) that are designated as Zone A on the effective FIRM where conventional hydrologic and/or hydraulic modeling methods could not be used to determine a 1% annual chance water surface elevation. This method will not be used in the Watauga Basin Plan mapping. Table 5 summarizes the estimated number of linear miles for each method to be applied in the Watauga River Basin. Attachments 2A and 2B depict the technical methods to be applied to each flooding source within the Watauga River Basin based a combination of Community Requests and State Recommendations. Table 5. Summary of Technical Methods for the Watauga River Basin Technical Method Detailed Study Riverine Limited Detailed Study Redelineation Use of Effective Information Total Estimated Linear Miles miles miles miles 0.70 mile miles The Watauga River Basin Study, which will include completion of the DEMs and preparation of updated flood hazard data, is scheduled to be completed by Date: December 21, 2006 Page 21

28 Variations from Community-Identified Needs and Priorities In some Basin Plans, it was necessary to deviate from the needs and technical methods identified by a county or community. The State used a quantitative ranking system to address all community needs identified for detailed study based on several factors. These factors included: The age of the effective FIRM analyses (studies based on older analyses receive a higher ranking) Likely flood mapping impacts (the greater the anticipated change to the flood elevation and/or floodplain boundary, the higher the ranking) Level of development (areas of more dense existing or anticipated development receive a higher ranking) Historical flood information (if gage data, high-water marks, inundation mapping, or community experience indicate a mapping problem, the higher the ranking) Mismatches with contiguous communities (significant mismatches in flood elevations and/or floodplain boundaries between adjacent communities receive a higher ranking) Whether any mitigation planning has been developed or is in the process of being developed (if so, the community receives a higher ranking) Appendix F summarizes the areas where the flood data development described above as part of this Final Basin Plan differs from the community-identified needs and priorities. Digital FIRMs Using the base maps and flood hazard data described above, DFIRMs will be produced in seamless state-wide format, including the unincorporated areas of each county in the Watauga River Basin and its incorporated communities on one set of DFIRM panels. The DFIRMs will depict flood hazard and related data (floodplain and floodway boundaries, base flood elevations, cross sections, and flood insurance zone designations) and non-engineering reference features (road names and locations, stream and river centerlines, shorelines, corporate boundaries, airports, schools, and bench marks). Because the counties within the Watauga River Basin are partially located in adjacent river basins (Catawba, Yadkin, French Broad and New), completion of the final effective state-wide DFIRMs will be dependent on completion of the basin studies for the adjacent basins. However, when the Watauga River Basin Study is completed, state-wide preliminary DFIRMs will be issued for the portions of counties and communities within the Watauga River Basin. (The community review and due process phases are discussed in more detail in Section V of this Final Basin Plan.) DFIRM panels will be tiled using the NCFMP tiling scheme and will be produced at either 1 =500 (for panels with detailed study or urban areas) or 1 =1,000 (for panels with Date: December 21, 2006 Page 22

29 only limited detailed study or rural areas). Table 6 summarizes the number and scale of DFIRM panels, the proposed schedule, and other basins affecting each county. Table 6. Summary of Digital FIRM Panels for the Watauga River Basin County Total DFIRM Panels * 1 = 500 * 1 = 1,000 * Projected Preliminary Date for Watauga Portion Fall 2007 Watauga Fall 2007 Other Basin(s) Projected Preliminary Date French Broad: 2007 Catawba: September 2006 New: 2008 Yadkin: 2007 *Includes total estimated DFIRM panels in county, not including adjacent basins. Also includes multi-county panels that are also counted for contiguous counties. V. COMMUNITY REVIEW AND DUE PROCESS As discussed in Section IV of this Basin Plan, when the Watauga River Basin Study is completed, state-wide preliminary DFIRMs will be issued to the impacted counties and communities for the portion of the county within the Watauga River Basin. As shown in Table 6 in Section IV, the state-wide preliminary DFIRM panels for the Watauga River Basin are anticipated to be issued by the fall of Subsequently, a preliminary DFIRM meeting will be held for county and community officials to present the results of the Watauga River Basin Study and state-wide preliminary DFIRM panels, answer questions, and explain administrative procedures. Shortly after the preliminary DFIRM panels are issued, a statutory 90-day appeal period will be initiated to allow counties, communities, and/or citizens to submit technical or scientific data to FEMA and the State to refute or contest new or revised base flood elevations and base map data shown on the preliminary DFIRMs and otherwise provide comments on the preliminary DFIRMs. Any and all appeals will be evaluated and resolved by FEMA in close coordination with the State, Dewberry, and the State s Flood Mapping Contractor. As the contiguous basin studies impacting a split-basin county are completed, state-wide preliminary DFIRM panels will be issued for the remaining portion(s) of the county. A preliminary DFIRM meeting will be held for those basins and the statutory 90-day appeal period will be provided and all appeals will be evaluated and resolved. After issuing preliminary DFIRM panels for all areas of a county and evaluating and resolving all appeals and community comments, the state-wide preliminary DFIRM panels will be finalized. FEMA s Map Service Center will print and distribute the official Date: December 21, 2006 Page 23

30 DFIRMs to be used for flood insurance rating purposes. Additionally, the State will post the final state-wide DFIRMs on its Floodplain Mapping Information System for distribution and access to communities and the public via the Internet. During the community review and due process phase, many counties and communities will need to update their floodplain management ordinances; the communities will be given a 6-month period to adopt the updated DFIRMs and incorporate the DFIRMs into their ordinances. The NCEM Floodplain Management Branch and FEMA will coordinate this effort with the counties and communities that need to update their ordinances. Date: December 21, 2006 Page 24

31 APPENDIX A ATTENDANCE SHEETS FROM INITIAL SCOPING MEETINGS County November 20, 2003 Name Title/Agency Phone David Vance County Emergency Management Coordinator (828) Robert Wiseman County Manager (828) Gerry Benfield Jason Vance Bill Cook David Webb Butch Sholar Ordinance Administrator/Planning & Zoning, County High Country Council of Governments Town Administrator, Town of Banner Elk Public Works Director, Village of Sugar Mountain Assistant Emergency Management Coordinator, County (828) (828) (828) (828) (828) James Seaberg GIS Director, County (828) Connie Guinn Town Clerk, Town of Elk Park (828) Mary M. Shaw NFIP Planner, NCDEM (919) x226 Joan Craft Dewberry (703) Ed Curtis Scoping & Outreach Coordinator NCFMP (919) x369 Date: December 21, 2006 Page A-1

32 APPENDIX A ATTENDANCE SHEETS FROM INITIAL SCOPING MEETINGS (CONTINUED) Watauga County November 20, 2003 Name Title/Agency Phone David Law Town Manager, Town of Seven Devils (828) Kevin Rothrock Planning Director, Town of Blowing Rock (828) Frank Hayes Land Surveyor, Appalachian PLS & C (828) George Cole Planning Supervisor, Town of Boone (828) James Perry Environmental Planner, Town of Boone Planning & Inspections (828) Jimmy Warren Planning & Inspections, Watauga Co. (828) Randy Woodrow Planning & Inspections, Watauga Co. (828) Rick Sacbibit Dewberry (703) Mary M. Shaw NFIP Planner, NCDEM (919) x226 Joan Craft Dewberry (703) Ed Curtis Scoping & Outreach Coordinator, NCFMP (919) x369 Date: December 21, 2006 Page A-2

33 Appendix B SUMMARIES OF COMMUNITY-IDENTIFIED FLOOD MAPPING NEEDS The tables on the following pages provide summaries of flood mapping needs that have been identified by the counties and/or communities. County and Incorporated Community-Identified Mapping Needs Identifier Flooding Source Community Type of Study Priority Ranking Effective Zone County and Town of A Elk River Detailed Study High 1 A Banner Elk B Hanging Rock Creek Town of Banner Elk Detailed Study High 2 AE with Floodway C Shawneehaw Creek County Detailed Study High 3 AE without Floodway D Whitehead Creek Town of Banner Elk Detailed Study High 4 X E Sugar Creek Town of Banner Elk Detailed Study High 5 AE with Floodway F Little Elk Creek Trib 6 Town of Elk Park Limited Detailed Study High 9 X G Little Elk Creek Trib 6.1 Town of Elk Park Limited Detailed Study High 10 X Date: December 21, 2006 Page B-1