Preliminary Design of an Artificial Surfing

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Preliminary Design of an Artificial Surfing Reef
for Cocoa Beach, Florida by John Hearin M.S.
Ocean Engineering January, 2006 johnhearin_at_yahoo
.com
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Purposes of Cocoa Beach ASR

• Provide Brevard County with a world-class surfing
  reef break
• Stabilize shoreline and provide significant
  protection from beach erosion
• Provide a stable habitat for marine life
• Boost local economy

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Science of Surfing

• Dr. James Kimo Walker, Univ. of Hawaii
• Journal of Coastal Research, Special Issue 29,
  2001
• International Surfing Reef Symposiums (3)
• ASR Limited, New Zealand
• Dr. Kerry Black and Dr. Shaw Mead

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Surfing Terminology(Hutt et al., 2001)
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Wave Quality Factors

• Peel Angle
• Breaking Intensity

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Wave Peel Angle (Hutt et al., 2001)
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Surfing Skill Levels (Hutt et al., 2001)
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Peel Angles for Surfing Maneuvers(Scarfe, 2002)
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Refraction Reduces Peel Angle
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Wave Breaking Intensity
(Mead, 2003)
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Wave Breaking Intensity(Mead and Black, 2001b)
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Artificial Surfing Reefs (ASR)

• Cables Station, Australia, 1999
• Pratts Reef, California, 2000
• ASR Limited of New Zealand
• Gold Coast, Australia, 2000
• Mount Maunganui, New Zealand, under construction
• Planning and design phase
• Oil Peers, Ventura, CA
• Long Branch, NJ
• Palm Beach County, FL

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Cables Station, Australia
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Gold Coast ASR(ASR Ltd., 2004)
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Cocoa Beach Reef Site Selection

• Brevard County Public Beach Parks
• Sheppard Park
• Lori Wilson Park

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Sheppard Park(FDEP, 2005)
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Lori Wilson Park (FDEP, 2005)
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Tide Data
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Cocoa Beach Wave Data

• USACE Wave Information Studies 1980-1999
• Mean Wave Conditions
• Significant Wave Height 1.2m 3.9 ft
• Peak Period 7 s
• Direction 90 True (shore normal)

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Wave Height Probability
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Wave Period Probability
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Wave Direction Probability
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Beach and Bathymetry Surveys

• Shoreline to 30 ft deep ( 4000 ft 0ffshore)
• Kayak
• GPS receiver WAAS enabled ( 10 ft)
• Hand held sonar ( 1 ft)
• 4 equally spaced transits at each site
• Time, depth, position
• Depth corrected for tide (6 min intervals)

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Reef Design Parameters

• Wave Heights 2 10 ft / Mean 3.9 ft
• Wave Periods 5 14 s / Mean 7s
• Wave Direction 45 - 135 / Mean 90
• Reef Orientation shore normal (90)
• Breaking Intensity medium high
• Peel Angle Range 30- 60

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Wave Direction
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Wave Direction
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View looking Offshore
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Reef Analysis Results

• Average ride length 415 ft
• Average ride duration 42 s
• Beach break duration lt 10 s
• 400 increase in ride duration

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Reef Analysis Results

• Peel Angles 35- 70
• Average Peel Angle 53
• Within desired range
• Vortex Ratios 4.2 1.7
• Average Vortex Ratio 2.5
• Breaking intensities low to extreme
• Average Breaking Intensity high
• Within desired range

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Reef Analysis Conclusions

• Should produce a broad range of peel angles and
  breaking intensities
• Suitable for surfers at intermediate skill level
  and above
• Average ride 415 ft / 42 s
• Should break at low tide for waves gt 1.7 ft

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Reef Analysis Conclusions

• Should break at all tides for waves gt 5 ft
• Should produce ride-able waves 85
• Should produce good waves 45 (Hb 3ft)
• Should produce high intensity tube rides during
  favorable wave conditions at low and mid tides

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Reef Construction Materials

• Sand-Filled Containers
• Geosynthetic Materials
• Multi-celled modular design

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Multi-Celled Sand Filled Container during Fill
Operation
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Geosynthetic Material

• Inner Layer polymer coated woven polyester
  geomembrane (impermeable)
• Outer Layer geotextile protective covering
• Field tested 19 years without failure due to
  debris impact
• 40 year design life

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Modular Design
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Reef Construction

• Location surveyed using Differential GPS
• Anchors and restraints installed by divers
• Modules delivered on rollers
• Rollers mounted to support vessel
• Modules deployed empty and restrained by divers
• Filled in place from hopper barges using dredge
  pumps

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Reef Deployment (ASR,2004)
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Cost Estimates
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Artificial Reef Benefits

• Shoreline Stabilization and Erosion Protection
• Ecological
• Economic

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Brevard County Erosion Processes

• Longshore Current
• Natural flow is North to South
• Port Canaveral Jetties inhibit natural flow

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Beach Nourishment

• First project in 1974
• Current project began 2002
• 50 years
• 253,000,000
• Replaces lost sand
• Does not address cause of erosion

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Shoreline Armoring

• Sea Walls - protect upland structures but inhibit
  natural dune formation and shoreline equilibrium
  
• Groynes localized beach protection robs
  downstream beaches
• Does not address cause of erosion

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Submerged Offshore Reefs

• Dissipate wave energy offshore
• Rotate waves more normal to beach
• Reduces longshore currents
• Produce salients to stabilize beach
• Reduce erosion at shoreline

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Salient behind Submerged Reef
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Salient Formation
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Salient Formation(Black and Andrews, 2001a)

• B/S 0.1 Salient may not form
• B/S gt 0.1 Salient will form
• B/S gt 0.6 Tombolo may form

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Tombolos behind breakwaters
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Cocoa Beach Salient Prediction

• Reef Width (B) 400 ft
• Offshore Distance (S) 800 ft
• B/S 0.5
• Salient Amplitude 320 ft
• Salient Length 2562 ft
• Tombolo will not form
• May be possible to move reef closer
• Minimize paddle out
• Maximize spectator viewing

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Salient Cost Estimate

• Volume 220,000 cubic yards
• 7.25 per cubic yard (USACE)
• 1.6 million
• Moving reef closer to shore would reduce salient
  volume and cost

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Ecological Benefits

• Hard stable substrate will promote greater
  biodiversity than sandy bottom
• Artificial reefs off the Florida coast are very
  popular fishing and diving sites
• Gold Coast ASR of similar design was quickly
  populated with marine life and is a popular
  fishing, diving and surfing site

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Economic Benefits

• Travel and tourism largest industry in America
  16.9 million jobs
• 240 billion annual tax revenues
• Beaches 85 of all tourism revenue
• Cost benefit analysis of Miami Beach nourishment
  project 5001
• Cost benefit analysis of Gold Coast ASR project
  601

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Economic Benefits

• Sebastian Inlet Pro Surfing Contest 2005
  generated gt 1.3 million for Brevard County
• World Class Surf Contest in downtown Cocoa Beach
  could generate gt 2 million

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Economic Benefits

• Cocoa Beach ASR would become a premier break on
  the East Coast of USA
• ASR would bolster Brevard Countys reputation as
  surf capital of the East Coast
• Attract world class surfers and contests
• Provide boost to local economy

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Alternative to Existing Beach Nourishment Plan

• 24 ASRs along Brevard Coast
• Protect 24 miles of coastline
• 40 year life
• 110 million (including salients)
• Widen shoreline
• Stabilize shoreline
• Mitigate marine habitat loss
• Improve surfing

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Alternative for Mid-Reach
ASR
Reef Balls (Fish Habitat)
Salient
Original Shoreline