2016 NC Coastal Local Governments Annual Meeting

Transcription

1 6 NC Coastal Local Governments Annual Meeting NCFMP Coastal Map Maintenance Flood Study Updates and Changes April, 6 Tom Langan, PE, CFM Engineering Supervisor NCEM-Risk Management - Floodplain Mapping Program

2 NCFMP Coastal Restudy Scale Entire Coastline Barrier Islands Closed Coast Sounds Albemarle, Pamlico Intracoastal Waterway Rivers Scope Storm Surge Onshore Wave Analysis Storm Frequency Analysis Coastal Hazard Analysis and Mapping DFIRM Production Study QA/QC NCFMP, Independent Contractor, FEMA and Academia

3 Sea Level Rise and Climate Change on the FIRMs FEMA maps coastal flood hazards are based on existing shoreline characteristics, and wave and storm climatology at the time of the flood study. In accordance with the current Code of Federal Regulations, FEMA does not map flood hazards based on anticipated future sea levels or climate change. Over the lifespan of a study, changes in flood hazards from sea level rise and climate change are typically not large enough to affect the validity of the study results. In accordance with the Biggert-Water Flood Insurance Reform Act of, FEMA is to establish a Technical Mapping Advisory Council that will provide recommendations to FEMA on flood hazard mapping guidelines including recommendations for future mapping conditions, the impacts of sea level rise and future development. FEMA will be required to incorporate future risk assessment in accordance with the recommendations of the Council.

4 FACTORS CONTRIBUTING TO COASTAL MAP CHANGES

5 Additional Hurricanes since 98 Influences JPM Storm Parameters and Probabilities (Central pressure, forward speed and heading, wind speed and direction, and radius of maximum winds) JPM Storms Effective 3 New Studies - 675

6 Surge Model GRID/MESH Resolution ADCIRC MESH (Yellow) ft FEMA SURGE GRID (98) (Blue) 6,67 x 6,67-ft

7 Surge Model GRID/MESH Extents ADCIRC MESH (Yellow) 45-ft Elevation FEMA SURGE GRID (98) (Blue) Effective Coastal Flood Extents (Blue Area)

8 Topographic Constrictions Highest water levels in inlets as water builds from winds and surge. FEMA Surge NM grid could not simulate this Phenomenon. Hurricane Sandy Storm Track Image source:

9 Wave Setup ADCIRC/SWAN Wave Setup (..8 ft, Avg.4 ft) (Yellow) Effective Empirical wave setup computed (.6.6 ft) Setup Open Coast Only Pender - Topsail Beach and Surf City Onslow and Carteret

10 Extratropical Storms Extratropical Storms Contribute to -percent surge level (red) Combined JPM/EST Surge Locations (blue)

11 Overland Wave Analyses No Effective Overland Wave Analyses (Yellow) Restudy Transects (Red Lines) Effective 783 Transects New Studies,739 Transects 9 New Counties (New FEMA Sheltered Water Guidelines and Specifications)

12 Reverse Transects County With Effective Reverse Transects (Yellow) Restudy Reverse Transects (Red Lines) Transects Effective - 67 New Studies 9 (4 Counties)

13 Primary Frontal Dune Refinement Effective VE Zone (Yellow) Restudy PFD and VE Zone Extent (Black/White Line)

14 Wave Runup Runup Transects (Yellow) Runup Based VE Zone (Red) Effective No BFEs based on Runup

15 Coastal/Riverine Combined Probability Effective Combined Probability (Yellow) 9 Counties

16 COASTAL FLOOD STUDY REVISION CHANGES

17 Statewide Surge Values % Surge (ft)

18 Statewide Surge Differences Negative Values New surge higher than effective Positive Values New surge lower than effective

19 Statewide Base Flood Elevation (BFE) Changes

20 Building and NFIP Policy Changes County Buildings NFIP Policies V Zone A Zone V Zone A Zone Current Updated Changes Current Updated Changes Current Updated Changes Current Updated Changes Beaufort - 5 5,3 6,49 (4,954) ,746,53 (,693) Brunswick 6,468,438 (5,3) 7,6,97 3,36 5, (4,5) 5,94 8,79,985 Camden - - -,48,43 (988) (34) Carteret 3,7,59 (,54) 4,5 6,87,37,6 387 (874) 5,93 5,9 68 Chowan (368) (87) Craven ,66 8, ,5,59 44 Currituck,97 6 (97) 7,,767 (4,53) (564),95 74 (,) Dare 5,,73 (3,7) 4,867,67 (,7) 3,3,6 (,38) 4, 6,7 (8,3) Hyde 7 - (7) 6,636 5,43 (,4) 3 - (3),355,77 (78) Jones New Hanover,869,49 (,44) 7,6 9,74,4,8 93 (,95) 4,45 5,47, Onslow 3,484,39 (,445) 3,77 7,7 3,5,7 536 (535) 87, Pamlico ,955 3,8 (,44) 8 7 (),667,9 (538) Pasquotank ,754 3,86 (,938) - - -,5 985 (,4) Pender,953,686 (67) 4,953 5,87 97,99 8 (79),93, Perquimans -,6 76 (94) (99) Tyrrell - - -,7,68 (454) (4) Totals 4,65 9,733 (4,88) 4,747 97,74 (7,5) 4,85 4,66 (,79) 47,47 38,79 (8,68) () - Indicates net reduction in building or policies in V or A Zone.

21 JUNE 3, 6 SCHEDULED PRELIMINARY ISSUANCE DRAFT DATA BEAUFORT, CARTERET, CRAVEN, DARE, HYDE, JONES, ONSLOW, PAMLICO, AND TYRRELL

22 Beaufort Co. Coastal Changes: BFEs Buildings VE 5 Added AE 4,954 Removed

23 Carteret Co. Coastal Changes: BFEs Buildings VE,54 Removed AE,37 Added

24 Carteret Co. Coastal Changes: BFEs Buildings VE,54 Removed AE,37 Added

25 Craven Co. Coastal Changes: BFEs Buildings VE 77 Added AE 74 Added

26 Dare Co. Coastal Changes: BFEs Buildings VE 3,7 Removed AE,7 Removed

27 Dare Co. Coastal Changes: BFEs Buildings VE 3,7 Removed AE,7 Removed

28 Hyde Co. Coastal Changes: BFEs Buildings VE 7 Removed AE,4 Removed

29 Jones Co. Coastal Changes: BFEs Buildings VE No Change AE 9 Added

30 Onslow Co. Coastal Changes: BFEs ONSLOW PENDER CARTERET JONES CARTERET Buildings VE,445 Removed AE 3,5 Added

31 Pamlico Co. Coastal Changes: BFEs Buildings VE 4 Added AE,44 Removed

32 Tyrrell Co. Coastal Changes: BFEs Buildings VE No Change AE 454 Removed

33 POST-PRELIMINARY PROCESSING Preliminary panels are issued Federal Register Notification (& 3 day comment period) notices in local newspaper 9-day Appeal/Protest Period Educational/Open House Meeting(s) Resolution of Appeals and Protests Resiliency Meeting: tie-in Risk data with Mitigation Plans The 6-month Compliance Period Letter of Final Determination from FEMA Map Adoption and Update of Flood Damage Prevention Ordinance

34 IMPORTANT DATES Preliminary Issuance: June 3, 6 Beaufort County Carteret County Craven County Dare County Hyde County Jones County Onslow County Pamlico County Tyrrell County Next Preliminary Issuance: Late 6 Bertie County Martin County Washington County

35 / QUESTIONS?

36 NC Division of Emergency Management Risk Management Office Floodplain Mapping Program Contact Information Tom Langan PE, CFM John Gerber Presenter-Engineering Supervisor NFIP Coordinator (99) 8538 (99) Randy Mundt, AICP, CFM Outreach Coordinator (99) Federal Emergency Management Agency -877-FEMA-MAP

37 POST-PRELIMINARY STATUS: Brunswick, New Hanover, and Pender, and Counties Preliminary flood hazard data (FIS/FIRM) released: August 9, 4 9-Day Appeal/Protest Period: Ended January 6, 6 Meetings with Public Officials: Held in fall of 4 Public Participation Meeting: Held in fall of 5 Opportunity for public to view, comment on, and ask questions about the new flood hazard data Revised Preliminary Panels: (tent.) Fall 6 (w/ 3-day comment) Letter of Final Determination: TBD; estimate winter 6-7 for issuance ; FEMA determines flood hazard data is official for flood insurance rating and floodplain management applications Effective Data (for Insurance Rating): Summer 7 (estimate)

38 POST-PRELIMINARY STATUS: Camden, Chowan, Currituck, Pasqoutank, and Perquimans Counties Preliminary flood hazard data (FIS/FIRM) released: November 3, 5 9-Day Appeal/Protest Period: PENDING; EXPECT SUMMER 6 Meetings with Public Officials: NOVEMBER 7, 5 Public Participation Meeting: APRIL 9,,, 6 Opportunity for public to view, comment on, and ask questions about the new flood hazard data Revised Preliminary Panels: UNKNOWN (DEPENDENT ON APPEALS) Letter of Final Determination: TBD; estimate winter 6-7 for issuance ; FEMA determines flood hazard data is official for flood insurance rating and floodplain management applications Effective Data (for Insurance Rating): Summer 7 (estimate)

39 Effective and Update Study Comparison Effective New Coastal Studies Storm Surge and Nearshore Waves Surge Model FEMA Surge ADCIRC/SWAN Nearshore Wave Model None SWAN Surge Study Completion Year 98 USGS quad sheets, NOAA nautical charts and aerial photos. NC LiDAR data and numberous bathymetric sources Topo/Bathy Data Sources Average Near Shore GRID (Effective)/Mesh (New) Spacing (ft) 676 (Dare is,5) Wave Setup Method Empirical Hydrodynamic (ADCIRC/SWAN) Wave Setup Extents Open Coast Only 9 Counties Surge Water Level Statistical Method JPM - JMP/EST (Dare/Currituck) Combined JPM/EST Overland Wave Analysis Data Overland Wave Analysis 9 Counties 9 Counties Number of WHAFIS Transects 783,739 Reverse WHAFIS Transects 67 9 Runup Contributes to Regulatory BFEs No Yes

40 AUGUST 3, 4 PRELIMINARY ISSUANCE BRUNSWICK, PENDER AND NEW HANOVER

41 Brunswick County Changes: BFEs Buildings VE 5,3 Removed AE 3,36 Added Negative Values New BFE higher than effective Positive Values New BFE lower than effective

42 New Hanover County Changes: BFEs Buildings VE,44 Removed AE,4 Added

43 Pender County Changes: BFEs Buildings VE 67 Removed AE 97 Added

44 NOVEMBER 3, 5 PRELIMINARY ISSUANCE CAMDEN, CHOWAN, CURRITUCK, PASQUOTANK, AND PERQUIMANS

45 Camden County Changes: BFEs Buildings VE No Change AE 988 Removed

46 Chowan County Changes: BFEs Buildings VE Added AE 368 Removed

47 Currituck County Changes: BFEs Buildings VE 97 Removed AE 4,53 Removed

48 Pasquotank Co. Changes: BFEs Buildings VE No Change AE,938 Removed

49 Perquimans Co. Changes: BFEs Buildings VE Added AE 94 Removed

50 Why the Coastal Flood Risk Study is Being Updated? Current surge analysis is from the early98 s New climatological data based on recent storms Computing Resources updates since 98 s Updated coastal hazard methodologies and modeling (LIMWA, PFD and % Runup) Updated elevation data and imagery Improvement in GIS technologies, improves coastal mapping accuracy Absence of effective overland wave analyses for some Counties