DFIRM SubcommitteeDFIRM SubcommitteeUpdateUpdate

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Challenges RemainChallenges Remain

Climate Change and Sea Climate Change and Sea Level RiseLevel Rise: Identify sea : Identify sea level rise timeframe and level rise timeframe and associated critical issuesassociated critical issues

Data ManagementData Management: Identify : Identify ways to improve data ways to improve data collection and management collection and management for storm surge modelingfor storm surge modeling

Land Use and ZoningLand Use and Zoning: Use : Use of coastal land use codes of coastal land use codes and robust community and and robust community and land use planningland use planning

Efficient StandardsEfficient Standards: Materials : Materials research supporting affordable research supporting affordable and stronger protection and stronger protection structures structures

Surge ModelsSurge Models: Improving : Improving protection predictive tools protection predictive tools

Appealing FEMA Appealing FEMA Digital Flood Insurance Rate MapsDigital Flood Insurance Rate Maps

The Preliminary DFIRMS result in a The Preliminary DFIRMS result in a significant conversion of A Zones to V significant conversion of A Zones to V zoneszones

Building within V Zones results in Building within V Zones results in increased construction Costsincreased construction Costs

Federal Assistance is unavailable in V Federal Assistance is unavailable in V ZonesZones

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Technical IssuesTechnical IssuesModeling SoftwareModeling Software– ADCIRC: Advanced CIRCulation ModelADCIRC: Advanced CIRCulation Model

Coastal Surge Model determines Still water Coastal Surge Model determines Still water elevation (SWEL)elevation (SWEL)

– STWAVE:Steady state spectral STWAVE:Steady state spectral WAVEWAVE Model ModelCoastal Wave Model Which Generates Near shore Coastal Wave Model Which Generates Near shore WavesWaves

– WHAFISWHAFISWave height model which computes wave crest Wave height model which computes wave crest elevations based on SWELs Output From ADCIRCelevations based on SWELs Output From ADCIRC

Determines the Flood HAZARD ZONE and Determines the Flood HAZARD ZONE and FLOODPLAIN MAP ELEVATIONS based on FLOODPLAIN MAP ELEVATIONS based on WAVE HeightsWAVE Heights

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Justification For DFIRM Justification For DFIRM ReevaluationReevaluation

Calibration errors are present associated Calibration errors are present associated with the hindcast for Hurricane RITA: Errors with the hindcast for Hurricane RITA: Errors in Predicted High Water Marks (HWM) in Predicted High Water Marks (HWM) compared to measured HWM are +/- 4.5 feetcompared to measured HWM are +/- 4.5 feet

An Examination of the Preliminary ADCIRC An Examination of the Preliminary ADCIRC GRID has revealed major Chenier ridges, GRID has revealed major Chenier ridges, levees, manmade features, and other levees, manmade features, and other topographic data were omitted from the topographic data were omitted from the modelmodel

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Preliminary Report FindingsPreliminary Report Findings

Low Resolution of Topographic data in all Low Resolution of Topographic data in all modelsmodels

Poor calibration of Surge modelsPoor calibration of Surge models

Improper application of input DataImproper application of input Data

Inconsistent Elevation Data between ModelsInconsistent Elevation Data between Models

Omission of Input DataOmission of Input Data

Finding: Dr. Joseph SuhaydaFinding: Dr. Joseph Suhayda

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DFIRM Path ForwardDFIRM Path ForwardFEMA Rejected CPRA/LRA Time Extension FEMA Rejected CPRA/LRA Time Extension RequestRequest

LRA & CPRA Provide Technical Assistance LRA & CPRA Provide Technical Assistance and Guidance to Coastal Parishes during and Guidance to Coastal Parishes during Appeal ProcessAppeal Process

Prepare Justification and Plan of Prepare Justification and Plan of Accomplishments - Time Extension Just.Accomplishments - Time Extension Just.

Recommendation to CPRA/LRARecommendation to CPRA/LRAAlternatives – Incentivize Storm Surge Risk ReductionAlternatives – Incentivize Storm Surge Risk Reduction

FEMA Presentation/Washington SupportFEMA Presentation/Washington Support

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