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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 - PowerPoint PPT Presentation
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Changes to FEMAMapping
John Grace, CFMCoastal Engineer - FEMA Region 1 - Boston
March 14, 2014 – The Soil and Water Conservation Society – Winter Conference
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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
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Risk MAP Project TimelineDiscovery
Meeting Project Kickoff Flood Study Review
Resilience Meeting
Final CCO Meeting
3-5 Year Process
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FEMA Mapping
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Detailed Study – Coastal Analysis
Stillwater Level (storm surge) + Wave Set-up
Overland Wave Propagation
Wave Runup and Overtopping
Primary Frontal Dune
Coastal analysis - includes 4 main components:
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Detailed Study – Stillwater Level (SWEL) with Gage Data
Return period gage analysisLinear interpolation between gage points
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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
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Detailed Study – Overland Wave Propagation
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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.
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Runup and Overtopping
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Primary Frontal Dune
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FLOOD RISK PRODUCTS
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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
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Changes Since Last FIRM
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• Annualized flood losses are displayed on the Census Block Data
• Aimed at depicting general flood loss areas
CITY OF REVERE250288
Flood LossVery Low
Low
Medium
High
Very High
Flood Risk Assessment
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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
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Wave Height GridsProvided for 1%annual chance floods
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Flood Risk Report
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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