A Numerical Simulation of the Hurricane Charley Storm Surge

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A Numerical Simulation of the Hurricane Charley
Storm Surge
R.H. Weisberg and L. Zheng Charlotte Harbor
Watershed Summit 2005 02/17/05
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Hydrodynamic Model FVCOM
Advantages

• Using unstructured triangle grid to better
  represent complex coastal and estuarine geometry.

• Using simple finite-difference which has simple
  discrete structures and computational efficiency.

3) Incorporating flooding/drying skill which is
critical for storm surges study.
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Prototypical Hurricane Structure (Holland, 1980)
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Lessons learned from Tampa Bay Based on
prototypical category 2 and 4 storms that
approach the region from several different
directions, at different approach speeds, and
making landfall at different locations.
http//ocg6.marine.usf.edu
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Model Grid for Tampa Bay Storm Surge Experiment
Minimum resolution 100 m
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Category 2 storm translating at 5 m/s
Courtney Compbell Causeway
W. Howard Frankland Bridge
Gandy Bridge
Sunshine Skyway Bridge
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Case I IRB landfall from the west. Case II
Translation up the Bay. Case III Coast parallel
from the south Case
IV Coast parallel from the north
Arrow landfall time
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Category 2 storm translating at 5 m/s
Courtney Compbell Causeway
W. Howard Frankland Bridge
Gandy Bridge
Sunshine Skyway Bridge
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Case I IRB landfall from the west. Case II
Egmont Key. Case III Sarasota
Case IV Tarpon Springs Arrow landfall time
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Category 2 storm making landfall at Indian Rocks
Beach from the west with speeds of

• 5 m/s (?10 knot)

• 10 m/s (? 20 knot)

3. 2.5 m/s (? 5 knot)
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IRB landfall from the west with translation
speeds of 5 m/s, 10 m/s, and 2.5
m/s. Arrow landfall time
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Storm making landfall at Indian Rocks Beach from
the west with speeds of 5 m/s

• Category 2

• Category 4

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IRB landfall from the west at 5 m/s for
category 2 category 4. Arrow landfall time
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The Surge in Tampa Bay Is Sensitive to
1) the storm intensity
2) the landfall location
3) the speed of approach and
4) the direction of approach.
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Hurricane Charley Storm Surge Simulation
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Punta Gorda
W. side of CH
E. side of CH
N. Pine Is.
Ft. Myers
Captiva
Sanibel Is.
Big Carlos Pass
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Courtesy of T. Liebermann
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8/13/2004 2100
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Model simulated surge time series
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• These simulated surges must be adjusted for
  the effects of
• non-tidal (seasonal) sea level variations,
• tides, and
• waves (we did not include these).

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Comparisons with available data.
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Summary 1) Based on the lessons learned from
Tampa Bay experiments we explain the relatively
small H. Charley surge by virtue of

• The approach direction from SW to NE and
  subsequent translation up the estuary.

• The rapid approach speed (?16 knots).

• The small storm radius (1020 km).

2) We account for the breach at North Captiva
Island by the large across-barrier-island sea
level gradient that occurred as the H. Charley
passed by.
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Acknowledgments This work was supported by
the Office of Naval Research, grants
N00014-98-1-0158 and N00014-02-1-0972 and by the
U.S. Geological Survey, order 4-SPSA-11920.
Changsheng Chen (UMassD) kindly shared the FVCOM
code, and Timothy Liebermann (SFWMD) kindly
shared the CH merged bathymetric and topographic
data set.