168 APPENDIX C: FLOODPLAIN MAPPING In 2001, the Institute for Business & Home Safety issued a report titled The Ten Most Wanted detailing the ten actions most likely to realize the greatest reduction in loss from natural disasters in the shortest time for a given investment. Their top item for flooding reads: “The highest priority should be given to improving maps of the flood plain and developing land use ordinances to avoid construction in flood-prone locations.” It is important to note that this recommendation includes two actions. The best flood maps in the world will not prevent losses without the political will to curtail continued construction in the floodplain. The first flood maps were paper Flood Hazard Boundary Maps (FHBM) and Flood Insurance Rate Maps. Flood Hazard Boundary Maps showed the boundary of the floodplain using approximate methods. Flood Insurance Rate Maps (FIRM) replaced these FHBMs. A FIRM includes a Flood Insurance Study with flood elevations and other hazard information needed to protect new construction from flood damage. Flood insurance rates for “pre-FIRM” structures, those built before the FIRM was published, are subsidized. The rates for “post FIRM” structures are based on how well protected they are from the mapped hazard. The national and local flood plain ordinances and insurance program depends on the accuracy of the flood maps. The National Flood Insurance Program (NFIP) began mapping West Virginia’s floodplains during the late 1970’s. In fact, only 49 of the 268 participating communities (municipalities and counties) joined the NFIP before 1980. Many of the maps used today are based on studies conducted over twenty years ago. Table C-1 shows the dates of floodplain maps by decades. Many of the recently revised maps may have resulted from a new flood control structure in the area, a revision to one section of the panel, or from a restudy of the area. Revisions based on a complete restudy are rare. Revisions that did not result from a complete restudy do not take into account development during the years since the first study. In addition to other problems, many of these older maps identified “Approximate A Zones” with no base flood elevation or precise flood plain
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APPENDIX C: FLOODPLAIN MAPPING In 2001, the Institute for Business & Home Safety issued a report titled The Ten Most Wanted detailing the ten actions most likely to realize the greatest reduction in loss from natural disasters in the shortest time for a given investment. Their top item for flooding reads: “The highest priority should be given to improving maps of the flood plain and developing land use ordinances to avoid construction in flood-prone locations.” It is important to note that this recommendation includes two actions. The best flood maps in the world will not prevent losses without the political will to curtail continued construction in the floodplain. The first flood maps were paper Flood Hazard Boundary Maps (FHBM) and Flood Insurance Rate Maps. Flood Hazard Boundary Maps showed the boundary of the floodplain using approximate methods. Flood Insurance Rate Maps (FIRM) replaced these FHBMs. A FIRM includes a Flood Insurance Study with flood elevations and other hazard information needed to protect new construction from flood damage. Flood insurance rates for “pre-FIRM” structures, those built before the FIRM was published, are subsidized. The rates for “post FIRM” structures are based on how well protected they are from the mapped hazard. The national and local flood plain ordinances and insurance program depends on the accuracy of the flood maps. The National Flood Insurance Program (NFIP) began mapping West Virginia’s floodplains during the late 1970’s. In fact, only 49 of the 268 participating communities (municipalities and counties) joined the NFIP before 1980. Many of the maps used today are based on studies conducted over twenty years ago. Table C-1 shows the dates of floodplain maps by decades. Many of the recently revised maps may have resulted from a new flood control structure in the area, a revision to one section of the panel, or from a restudy of the area. Revisions based on a complete restudy are rare. Revisions that did not result from a complete restudy do not take into account development during the years since the first study. In addition to other problems, many of these older maps identified “Approximate A Zones” with no base flood elevation or precise flood plain
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delineation. Many existing floodplain maps lack sufficient detail to easily and accurately locate affected property.
TABLE C - 1: JURISDICTIONS MAPPED BY DECADES One hundred sixty eight jurisdictions in West Virginia had their existing FIRMs developed before 1990. Table C – 2, at the end of this appendix, lists the participating communities in West Virginia and the dates of the most recent revisions to their FIRMs. Small watersheds and headwaters areas (generally one square mile or less) have never been mapped in a systematic fashion. This limits the potential for use in hydrologic modeling programs. Some unmapped areas have experienced growth in residential and commercial construction. This new construction has been sited without the benefit of a known base flood elevation. All jurisdictions should consider using a total development condition for hydrologic modeling when developing floodplain maps for small watershed areas. Through FEMA’s Map Modernization Initiative, many maps in West Virginia will be improved and converted to Digital Flood Insurance Rate Maps (DFIRM) (See Map Concersion Schedule Table C-3). DFIRMs consist of all the data required to create the hard copy FIRM. The digital format allows flood maps to be incorporated into the community’s mapping system and tied into other geographic information systems. However, the simple conversion of a paper FIRM to a digital format does not improve the engineering quality of the map and usually does not include development occurring after the original map was published, even though the DFIRM has a more recent published date. One additional problem with DFIRM maps has become evident. Some jurisdictions in West Virginia do not have the technological capabilities to take advantage of them. Switching from a paper map to a digital map, if the jurisdiction does not have the necessary hardware, software and people trained to use them, is a waste of scarce resources. The Task Force recommends that Development of DFIRMS should consist of value-added mapping, not a simple conversion of a paper map to a digital file (DFIRM). All new DFIRMs should include a delineation of the floodway and eliminate approximate A zones. The Task Force also recommends that West Virginia initiate a program to provide hardware, software and training in the use of Geographic Information Systems (GIS) and DFIRMs to all West Virginia jurisdictions in the National Flood Insurance Program.
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In addition the Task Force recommends that FEMA to dedicate sufficient funds to re-map all watersheds in the State using a modern suite of mapping technology that will: � Create enhanced elevation and terrain data, as well as more detailed
hydrographic networks to improve flow models and flood risk assessment. � Accurately identify the channel shape. � Eliminate all “Approximate A” zones by conducting detailed studies to
delineate more accurate and realistic flood-prone areas. � Delineate floodplains in previously unmapped areas. � Upgrade the quality of floodplain maps statewide with priority given to heavily
populated floodplain areas, areas of repetitive losses, areas with high levels of flood damages and areas with insufficient mapping as identified by the Map Needs Update Support System (MNUSS).
In addition, the Task Force recommends that all hydraulic studies conducted by or through Federal and State agencies within the State for the purposes of identifying, enhancing or developing floodplain areas should be required to delineate a floodway zone (in accordance with procedures used in the NFIP) with the study. Some structures affecting stream hydraulics (bridges, culverts, retaining walls, fill, etc.) were built after the data for Flood Insurance Rate Maps were collected and before the maps were published. Such “gap” structures may affect the delineation of the floodway and floodplain and should be cause for a restudy of the area. No existing program or process identifies these gap structures and initiates a restudy of the area. The Task Force recommends a partnership with the network of volunteer watershed associations be formed to identify gap structures throughout West Virginia. There are many reasons in addition to gap structures to revise and update a FIRM. These include: • To correct non- flood related features such as a change in a jurisdictions boundary. • To include better ground elevation data. • To reflect changes in ground elevations in the floodplain. • To revise flood data. • To submit new flood data. • To reflect a flood control project. The need for map revisions is tracked by the Mapping Needs Update Support System (MNUSS). MNUSS is maintained by FEMA but is based on data provided by the states. The existing staff at WVOES is inadequate to collect and input data for MNUSS that identifies flood hazard areas needing restudy. The Task Force recommends that FEMA provide funds for the Corps of Engineers to populate the MNUSS database as has occurred in other states such as Virginia and Pennsylvania. The Task Force further recommends that WVOES be provided the staff and resources to
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coordinate maintenance of floodplain maps in West Virginia. Jurisdictions experiencing greatest growth should be prepared first. Jurisdictions with older maps should be prepared next. No jurisdiction should have a FIRM more than five years old. Mapping in flood prone areas of West Virginia is generally inadequate to support disaster planning prior to a flood event, to determine evacuation routing and emergency response procedures during an event, and to direct recovery mitigation efforts after an event. To be useful maps need data on elevation (both floodplain and runoff catchments), property ownership (parcels, structures), infrastructure (roads, utilities), and hydrology (stream networks, watersheds), and historic flood zones. Currently there is no integrated, comprehensive Geographic Information System (GIS) employed to systematically collect, analyze and model flood event data and parameters. Both diachronic (as they change over time) and synchronic (as they exist at a particular point in time) analysis of flood events should be a required capability of a statewide flood management system. The production and availability of geographic information and maps relating to flood events is not well coordinated between Federal, State, and county/local agencies. Existing GIS data (e.g., DOQQs, parcel maps, County E-911 roads, etc.) may not be known or readily accessible to emergency responders during the course of a flood. During recent flooding, it was reported that some responders used road maps from gas stations or convenience stores to locate themselves because they did not have knowledge of or access to better maps at the scene. The Task Force recommends that WVOES make training in maps and map reading available to all Federal, State, local and volunteer personnel involved in flooding in West Virginia on a regular basis. Existing floodplain maps do not delineate potential flooding caused by failure of existing dams under either sunny day or heavy rainfall failure conditions. Dam failure inundation maps do exist for some Federal structures and selected State regulated dams. Other data, such as: high erosion areas ands soils, landslide areas, karst areas, mine ponds, mine blow-out data, mine subsidence areas, etc., is also available that would be beneficial on a FIRM or in a GIS layer compatible with the FIRM. Other data has never been systematically collected or made available such as: public and private culverts and stream crossings, highways bridges, railroad bridges, and abandoned bridges and pilings. In addition, small watersheds and headwater areas (generally one square mile or less) have not been mapped in a systematic fashion, thus limiting the potential for input into hydrologic modeling routines. Identifying and locating repetitive loss structures on floodplain maps is difficult at best. Some agencies (FEMA, WVOES, US Small Business Administration) have some data on repetitive loss structures that may or may not have accurate location information. In addition, different agencies compile information differently. For instance, the Small Business Administration collects data on businesses and individuals who apply for loans
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from them. FEMA on the other hand only collects data on structures insured by the National Flood Insurance Program. The Task Force recommends that a program to identify, locate or develop desired map information related to flooding be initiated by the West Virginia GIS Coordinator. This information should be made available to all State, Federal and local agencies on digital layers for use in disaster planning. In the past both State and Federal agencies have spent scarce resources to develop digital maps of the same regions. While the West Virginia Geographic Information System Coordinator has seen a reduction in these uncoordinated efforts, communication and coordination between agencies still needs improvement. Three basic items would result in additional improvements in this area: • All agencies preparing maps or map data include elevation data for all structures. • All new elevation data developed for West Virginia State and local agencies should be acquired using LIDAR or a similar modern imaging technique. • All agencies preparing maps or map data notify the West Virginia Geographic Information System Coordinator prior to initiating the program. If necessary, a new “off-budget” State instrumentality (such as the West Virginia State Mapping Board) should be initiated to develop and maintain digital mapping statewide for flood and other disaster planning. The program should be implemented and operated in cooperation with Federal partners and State agencies with hydrologic-mapping expertise or regulatory responsibilities such as the Department of Environmental Protection, Department of Transportation, Division of Natural Resources, Geological and Economic Survey, Geographic Information System Coordinator Office, and Geographic Information System Technical Center, or regional, county, and local offices (E-911 Centers), and/or non-governmental watershed organizations such as Canaan Valley Institute. One of the key objectives of the FEMA modernization plan is to increase local involvement in, and ownership of, the flood mapping process. To meet this objective, FEMA developed and implemented the Cooperating Technical Partners (CTP) initiative. It is envisioned that the initiative and this guidance will evolve as technologies and the capabilities of FEMA's Partners grow. More information on the CTP program can be found at: www.fema.gov/mit/tsd/CTP_main.htm In addition, the State could become a Cooperating Technical State (CTS) with FEMA. This would involve a long-range State project with one agency in charge. It would involve the State collecting data and conducting studies for development of new DFIRMs. If the actual flood studies were contracted out to consultants, many State agencies could manage the program. One problem with this is the cost to FEMA to hold public meetings and respond to comments and suggestions before the studies are accepted. Unless the necessary funds
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are allocated to West Virginia studies by FEMA, West Virginia might wind up with lots of data and no final product to show for it. These studies would generate better data than is currently available. Floodplain ordinances allow for use of best available data for use in regulatory activities but best available data cannot be used to require or calculate the premium rate of flood insurance. All State and Federal agencies should adopt current FEMA guidelines for floodplain mapping, in defined project areas, that is consistent with the Federal Emergency Management Agency’s document “Draft Guidelines and Specifications for Flood Hazard Mapping Partners.” The Task Force recommends that State agencies, local governmental units and Regional Planning and Development councils assist in the mapping process by becoming Cooperating Technical Partners (CTP) in Flood Hazard Mapping. The Task Force recommends that West Virginia investigate the possibility of becoming a Cooperating Technical State with FEMA in developing new flood studies and new DFIRMs. This investigation should be conducted by WVOES and the WV GIS Coordinator. Currently there are limited sources of funding available for flood mapping. FEMA has four programs with funding that is available to update flood maps. These include: • Post Disaster Funding (This program reviews areas where flooding exceeded the expectations given by the study.), • Cooperating Technical Partners Fund, • Map Modernization Fund, and • Limited Map Maintenance Program (This program redraws maps based on Letters of Map Change, Letters of Map Amendment and Letters of Map Revisions.) The Economic Development Authority has funneled some funds through the Regional Planning and Development Councils to convert paper FIRMs to Digital Flood Insurance Rate Maps. The Task Force recommends that WV GIS Coordinator, the WV Development Office, the Regional Planning and Development Councils and WVOES investigate obtaining additional funding to continue this effort. The Statewide Addressing and Mapping Board may have some in kind assistance available to assist in adding 911 addresses to floodplain maps or as a digital layer for use with DFIRMs. The Task Force recommends that the WV GIS Coordinator and WVOES coordinate this effort.
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FEMA Region III Schedule of Map Updates for West Virginia
Map Mod
County Community RP&DC Contractor Comments Address Zip Phone
2001 Monroe Co. I RI Issued 2002 All Approximate "A"
P.O. Box 350 24983 772-3083
2001 Monroe Co. Alderson (also in Greenbrier)
2001 Monroe Co. Peterstown P.O. Box 487 24963 753-9509
2001 Monroe Co. Union Non-Participating NSFHA Low flood Risk
2002 Hampshire Co. VIII MOD Issued 2003 P.O. Box 883 26757 822-7018
2002 Hampshire Co. Capon Bridge
PO Box 183 26711 856-3625
2002 Hampshire Co. Romney 260 School Street 26757 822-5118
2002 Jackson Co. V MOD Issued 2004 P.O. Box 800 25271 372-2011
2002 Jackson Co. Ravenswood 212 Walnut St. 26164 273-2621
2002 Jackson Co. Ripley 113 S. Church St. 25271 372-3482
2003 Cabell Co. II County PI Prelim issued Cabell Co. Comm. Rm 314 Court House 750 5th Ave.