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Changes to FEMA Mapping

Changes to FEMA Mapping. John Grace, CFM Coastal Engineer - FEMA Region 1 - Boston. March 14, 2014 – The Soil and Water Conservation Society – Winter Conference. Program Overview. Risk MAP Mapping – Flood hazard and risk identification Assessment – HAZUS and other risk assessment tools

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Changes to FEMA Mapping

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  1. Changes to FEMAMapping John Grace, CFM Coastal Engineer - FEMA Region 1 - Boston March 14, 2014 – The Soil and Water Conservation Society – Winter Conference

  2. Program Overview • Risk MAP • Mapping – Flood hazard and risk identification • Assessment – HAZUS and other risk assessment tools • Planning – Hazard mitigation planning and HMA grants • Risk MAP Vision • Deliver quality data • Increase public awareness of flood risk • Encourage local/regional actions that reduce risk

  3. Risk MAP Project Timeline

  4. FEMA Mapping

  5. Detailed Study – Coastal Analysis Coastal analysis - includes 4 main components: • Stillwater Level (storm surge) + Wave Set-up • Overland Wave Propagation • Wave Runup and Overtopping • Primary Frontal Dune

  6. Detailed Study – Stillwater Level (SWEL) with Gage Data • Return period gage analysis • Linear interpolation between gage points

  7. Detailed Study – Wave Setup • Numerically determined at each coastal transect • Determining factors • Average nearshore slope [depth of wave breaking to SWEL] • Deepwater significant wave height • SWEL + Wave Setup = Total Water Level (TWL) • Areas where floodplain is restrictive, wave setup is removed and SWEL is mapped • Constrictions such as low bridges • Narrowing of the floodplain

  8. Detailed Study – Overland Wave Propagation

  9. LiMWA (Limit of Moderate Wave Action) • Areas subject to wave heights greater than 1.5 feet, but less then 3 feet. • Standard flood insurance requirements apply. • No regulatory requirement. (Rhode Island requires V zone regulations) • Defines the coastal A zone.

  10. Runup and Overtopping

  11. Primary Frontal Dune

  12. Flood Risk Products

  13. Flood Risk Products • These products are intended to help communities better understand and communicate flood risk • Non - Regulatory • All of these products are GIS based The following flood risk products may be available: • Changes Since Last FIRM • Flood Risk Assessment • Contributing Engineering Factors • Wave Height Grids • Flood Risk Report

  14. Changes Since Last FIRM

  15. Flood Risk Assessment • Annualized flood losses are displayed on the Census Block Data • Aimed at depicting general flood loss areas

  16. Contributing Engineering Factors • Provide insight into the factors behind the increase or decrease in the flood hazard areas • Can prove to be useful for planning and mitigation measures

  17. Wave Height Grids Provided for 1% annual chance floods

  18. Flood Risk Report

  19. WEB LINKS • Preliminary Data • www.fema.gov/preliminaryfloodhazarddata • Effective Data (including Future Effective) • msc.fema.gov • National Flood Insurance Program • www.floodsmart.gov • Flood Insurance Reform Act • www.fema.gov/flood-insurance-reform-act-2012

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