Mingo County, WV Community Coordination Preliminary Flood Insurance Study and Flood Insurance Rate Map Thursday, September 25, 2014
Overview Preliminary Materials Preliminary FIS Report Digital Flood Insurance Rate Map (DFIRM) Preliminary FIRM Levee Seclusion Preliminary SOMA Flood Hazard Mapping Fact Sheet
Preliminary Materials Flood Insurance Study (FIS) Report hard copy and digital Flood Insurance Rate Map (FIRM) panels - hard copy and digital
Preliminary Materials (continued) Preliminary Summary of Map Actions (SOMA) Flood Hazard Mapping Fact Sheet
Preliminary FIS Report FIS report narrative includes all revised Tug Fork study data within the county, including the following revised tables and exhibits: Summary of Discharges Table Manning s n Values Table Flood Profiles and Floodway Data Tables Tug Fork (entire reach in county) Buffalo Creek, Laurel Fork, Marrowbone Creek, Mate Creek, and Pigeon Creek, Trace Fork, West Fork Twelvepole Creek (backwater reaches)
Preliminary FIS Report - Hydrologic and Hydraulic Analyses Tug Fork and detailed study tributaries New detailed hydrologic and hydraulic analyses have been performed, replacing all previously effective detailed stream reaches as part of this update In general, Base Flood Elevations (BFEs) have been reduced along Tug Fork and impacted tributaries, resulting in reduced flood hazard areas
Preliminary FIS Report Floodway Concept
Components of a Digital Flood Insurance Rate Map (DFIRM) Base + New Topography (LiDAR) + GIS Flood Data = DFIRM
Preliminary FIRM Effective Floodplain (FIRM 0140E), Tug Fork and Miller Creek map scale shown at 1 = 1,000 [note: above image is shown at 200%] Effective Floodplain (FIRM 0139F), Tug Fork and Miller Creek map scale shown at 1 = 500 [note: above image is shown at 100%]
Preliminary FIRM Updates Detailed floodplains Tug Fork New detailed hydrologic and hydraulic analyses for 66.9 miles Boundaries were re-delineated for Tug Fork, based upon updated topographic data (LiDAR) Portions of boundaries in the backwater areas were revised to tie-in with detailed study streams: Buffalo Creek, Laurel Fork, Marrowbone Creek, Mate Creek, and Pigeon Creek, Trace Fork, West Fork Twelvepole Creek Data developed as part of Tug Fork Watershed Discovery project, located in West Virginia, Kentucky, and Virginia (9 counties & 15 cities/towns)
Preliminary FIRM Updates (continued) Zone A (approximate) floodplains Preliminary FIRM Database will include model-backed cross section data for the county No updated approximate analyses Base map combined with floodplain data Improves accuracy of floodplain determinations
Preliminary FIRM Updates (continued) GIS based, county-wide format Preliminary DFIRM Shapefiles (SFHA, floodway, cross-sections, BFEs, maps, political boundaries, etc.) This is preliminary data that may be subject to appeal, and cannot be used for making final determinations. The data can be used for demonstration purposes only and cannot be distributed or published without the consent of FEMA. Helpful for reviewing with your community s GIS data
Levee Seclusion
Levee Seclusion Non-Accredited Levees Tug Fork s 3 Impacted Levee Systems Shown on FIRM panels 0216F, 0217F, and 0331F Affects the City of Williamson and the Town of Matewan Flood hazard information is shown as a snapshot of the prior (October 2, 2012) effective information NFIP requirements of 44 CFR Section 65.10 must be met for levee accreditation Upon accreditation, flood hazard information will be mapped upon the latest Tug Fork analyses, and the levee seclusion notation removed from the FIRM panels
Preliminary SOMA Background Letters of Map Change (LOMCs) are legally binding changes to the map Many LOMCs are not incorporated in the new maps due to map scale constraints SOMAs assess all valid LOMCs compared against the new FEMA study Category 1: shown on the new FIRM panel Category 2: not shown on the new FIRM panel due to map scale limitations (revalidated after the new FIRMs become effective) Category 3: superseded, and no longer valid, due to revised flood hazards Category 4: must be re-determined
Flood Hazard Mapping Fact Sheet Summarizes information about the NFIP and how the new study data was developed Answers common questions related to the new maps Provides a generalized mapping process timeline