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DFIRM Subcommittee Update

DFIRM Subcommittee Update. Challenges Remain. Climate Change and Sea Level Rise : Identify sea level rise timeframe and associated critical issues Data Management : Identify ways to improve data collection and management for storm surge modeling

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DFIRM Subcommittee Update

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  1. DFIRM SubcommitteeUpdate

  2. Challenges Remain • Climate Change and Sea Level Rise: Identify sea level rise timeframe and associated critical issues • Data Management: Identify ways to improve data collection and management for storm surge modeling • Land Use and Zoning: Use of coastal land use codes and robust community and land use planning • Efficient Standards: Materials research supporting affordable and stronger protection structures • Surge Models: Improving protection predictive tools

  3. Appealing FEMA Digital Flood Insurance Rate Maps • The Preliminary DFIRMS result in a significant conversion of A Zones to V zones • Building within V Zones results in increased construction Costs • Federal Assistance is unavailable in V Zones

  4. Technical Issues • Modeling Software • ADCIRC: Advanced CIRCulation Model • Coastal Surge Model determines Still water elevation (SWEL) • STWAVE:Steady state spectral WAVE Model • Coastal Wave Model Which Generates Near shore Waves • WHAFIS • Wave height model which computes wave crest elevations based on SWELs Output From ADCIRC • Determines the Flood HAZARD ZONE and FLOODPLAIN MAP ELEVATIONS based on WAVE Heights

  5. Justification For DFIRM Reevaluation • Calibration errors are present associated with the hindcast for Hurricane RITA: Errors in Predicted High Water Marks (HWM) compared to measured HWM are +/- 4.5 feet • An Examination of the Preliminary ADCIRC GRID has revealed major Chenier ridges, levees, manmade features, and other topographic data were omitted from the model

  6. Preliminary Report Findings • Low Resolution of Topographic data in all models • Poor calibration of Surge models • Improper application of input Data • Inconsistent Elevation Data between Models • Omission of Input Data Finding: Dr. Joseph Suhayda

  7. DFIRM Path Forward • FEMA Rejected CPRA/LRA Time Extension Request • LRA & CPRA Provide Technical Assistance and Guidance to Coastal Parishes during Appeal Process • Prepare Justification and Plan of Accomplishments - Time Extension Just. • Recommendation to CPRA/LRA • Alternatives – Incentivize Storm Surge Risk Reduction • FEMA Presentation/Washington Support

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