Artificial Reef Design for Surfing By: Spicer Bak, M.S. Stevens Institute of Technology This material is based upon work supported by the National Science Foundation under Grant No.. NSF DGE-0742462

Why do this? Rising Sea Levels/Wave heights Growing Conflict with Surfer Groups and local Government Long Branch, NJ - October 2006 ASBPA National Conference

Beach Protection Waves are a type of energy 2 basic causes of erosion Waves = energy Energy moves sand Beach gets narrower 2 basic causes of erosion Longshore Sediment transport Cross-shore erosion Current popular protection Groynes - Long-shore Breakwaters/seawalls Cross-shore

Groynes - Long-shore sediment transport protection Advantage: Keeps sand Encourages sea life Disadvantage Eyesore - not pretty Need a field to adequately protect

Sand moves collects on the updrift side http://changingcoastline.com/dunes-edge/beach-restoration/hard-engineered-solutions/

Break waters & sea walls Wall at edge of water Stops wave energy Breakwater Parallel to shore Dissipates waves Don’t work well, ugly Galveston, Texas

Science Of Surfing Peel Angle Velocity Wave Classification Vortex Ratio Surf Similarity Parameter

Peel Angle Used to classify the wave Surfer Velocity Ways to classify a wave

Peel Angle Classify waves for beginner intermediate and expert using the peel angle and expert, this is why some waves are preferred by beginners and others by more advanced surfers

Classification of Waves BEGINNER INTERMEDIATE ADVANCED/EXPERT First set of numbers are difficulty level, 2nd set are peel angles, 3rd’: Numbers on the right are surf similarity parameteer (explained later) Hutt, Black and Mead (2001)

Vortex ratio (Y) = Vortex length to width ratio Vortex ratio, a way to classify the barrel Wave parameters used for curve fitting; vortex length (l), vortex width (w), angle (θ), and wave height (H), orthogonal seabed gradient (X’) Mead and Black (2001)

Surf Similarity Parameter ξb > 2.0 0.4 < ξb < 2.0 ξb < 0.4 Breaker Type Surging or collapsing Plunging Spilling Surfing Terminology ‘Unsurfable’ wave ‘Tubing’ or ‘hollow’ wave ‘Full’, ‘fat’, or ‘mushy’ wave Surf Similarity paramter ‘dictates’ type of wave from spilling surging or plunging… plunging is the best type for surfing Surging/Collapsing Plunging Spilling

Example Classifications Different types of waves with corresponding classifications Mead and Black (2001)

Reefs Disadvantages Advantages Construction difficult Time consuming Out of sight Design to protect against long- shore/cross-shore Provides: Capability for design for surf Adds marine life habitat Sheltered swimming Diving Comparable Cost Disadvantages Construction difficult Time consuming Still an emerging technology Mostly proprietary (as of right now) Proprietary – ASR ltd. from New Zealand has a patent that’s been pending for 10 years, they’re mainly the only company doing this sort of work in the world right now, have a base in orlando?

Refraction - Energy Wave straightens out Snell’s Law E=1/8  * g * H2 (q – measured w.r.t. shore normal) E=1/8  * g * H2 As wave approaches shore want’s to approach parallel to shore line (depth contours) wave slows down on the shallow part and causes it to rotate

Unprotected Unprotected waves create to make sand move

Coastal protection With protection sand stays put creates, rotates the energy of the wave making it more parallel to the shore, less sand moving down shore, creates a little sand bar inside of the reef (salient or tombolo) (tombolo is connected to the structure)

Design Giant Sand bags V - Shaped pattern Placed then filled General Design of a example reef bottom left is the design for boscome UK top right is the Mt. Reef design in new zealand

From Boscombe ( not considered a success) currently working to re-design and fix reef

Narrow Neck - Aus Both Right and left Beginners wave on inside

ASR design overview india goes off Video’s from ASR they are more or less Company plugs but interesting none the less