Title of Presentation - The Association of State Floodplain Managers

Report
Modeling to Revise Coastal Inundation and Flooding
Estimates in Georgia and Northeast Florida
Association of State Flood Plain Managers Conference
May 22, 2012
Christopher Bender, PhD, PE, D.CE — Taylor Engineering
Ashley Naimaster, EI— Taylor Engineering
William Miller, PhD, PE— Taylor Engineering
Tucker Mahoney, PE — FEMA Region IV
Overview
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Project background
About SWAN+ADCIRC
Model mesh development
Validation results
Production runs
Conclusions
Project Background
• FEMA multiyear coastal engineering analysis and
mapping effort
• 100-year storm surge elevations
• Model winds, hydrodynamics, offshore and nearshore
waves
• Georgia and northeast Florida
• Update DFIRMs
Study Location
• Entire coast of
Georgia and
Florida counties
north of Brevard
• Extend inland to
40 ft contour
Data and Methods
• Improved Data
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LiDAR data
Wind fields (simulate real events and synthetic events)
GIS data sets – land use, coastal features
• Improved Methods
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Better mesh/resolution
Better hydrodynamics - ADCIRC
Include wave setup – dynamically linked
Faster, more powerful, computers
SWAN+ADCIRC
• Water levels + currents + waves
• Parallelized code
• Forcing
• Wind speed, barometric pressure
• Tides
• Riverine flow
• Output
• Water surface elevation
• Velocity
• Wave height, peak period, mean period, direction
• Tightly-coupled
Input Data
• Recent LiDAR data captured for the
State with FEMA funds
• Aerial photography
• Land use with national, regional, and
local scale
• Field investigations
Model Mesh Development
• Surface-water Modeling
System
• Need to digitize:
• Obstructions to flow
• Flow paths
• Mesh quality
Model Mesh Development
Elevation (ft-NAVD)
Model Mesh Development
• 2.9 million nodes
• Minimum nodal spacing = 50 m
Spatially Variable Nodal Attributes
Wind reduction
roughness length
Manning’s n
Mesh Resolution
Average nodal spacing (ft)
Bathymetric Mesh
University of Central Florida
CHAMPS Lab
Hurricane Dora
• September, 1964
• Landfall near St. Augustine, FL
Hurricane Dora
Hurricane Dora
Setup at Maximum
Water Level (ft)
Hs at Maximum
Water Level (ft)
Hurricane David
• September, 1979
• Initial landfall near West Palm
Beach, FL. Exited near New
Smyrna Beach, FL, and made
final landfall near Savannah, GA
• Results presented do not include
waves
Hurricane David
Hurricane David
Production Runs
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~ 400 storms
Liveoak HPCC – Worldwinds, Inc.
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528 cores
Handles post-processing plots
Conclusions
• Preliminary results appear reasonable
• Next steps:
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Continued model validation
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Tidal validation
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Historical storm validation
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Wave data comparison
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Sensitivity testing with ADCIRC and SWAN parameters
Questions?

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