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

1. Provide Brevard County with a world-class surfing
   reef break
2. Stabilize shoreline and provide significant
   protection from beach erosion
3. Provide a stable habitat for marine life
4. 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)
Rating Description of Rating Peel Angle Limit (deg)
1 Beginner surfers 90
2 Learner surfers able to ride laterally along wave. 70
3 Surfers able to generate speed by pumping on the wave face. 60
4 Surfers able to execute standard surfing maneuvers 55
5 Surfers able to execute consecutive standard maneuvers 50
6 Surfers able to execute advanced maneuvers. 40
7 Top amateur surfers 29
8 Professional surfers 27
9 Top 44 professional surfers TBD
10 Surfers in the future TBD
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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)
Breaking Intensity Extreme Very High High Medium/High Medium
Vortex Ratio 1.6 - 1.9 1.91 - 2.2 2.21 - 2.5 2.51 - 2.8 2.81 - 3.1
Descriptive Terms Square, spitting Very hollow Pitching, hollow. Some tube sections Steep faced, but rarely tubing
Example Breaks Pipeline, Shark Island Backdoor, Padang Padang Kirra Point, Off-The-Wall Bells Beach, Bingin Manu Bay, Whangamata
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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
Station Name Trident Pier, Port Canaveral, FL
Date Established October 13, 1994
Tidal Bench Mark ID 872 1604 C / VM 12682 / PID AJ2449
MSL elevation Relative NAVD 1988 -1.0 ft
Mean Tide Range 3.47 ft
Diurnal Tide Range 3.97 ft
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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

1. Should produce a broad range of peel angles and
   breaking intensities
2. Suitable for surfers at intermediate skill level
   and above
3. Average ride 415 ft / 42 s
4. 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
Item Cost
Reef Modules Fabrication 1,000,000
Project Mobilization 50,000
DGPS Survey 50,000
Install Anchors 80,000
Sand Transport 500,000
Module Deployment 500,000
Sand Pumping 500,000
Materials 40,000
Equipment 150,000
Demobilization 50,000
Total 2,920,000
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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)

1. B/S 0.1 Salient may not form
2. B/S gt 0.1 Salient will form
3. 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