“World Class” Artificial Surf Reefs

The idea of a deep offshore reef, to refract incoming swell into inshore peaks is possible, this effect occurs in nature, but the very large size of the structure required and corresponding cost makes it uneconomical. Better to use a smaller structure that waves break directly onto and over- cost efficient/predictable outcome/patentable /commercially viable. Dumped ships? No, dumped anything will not deliver-reefs need accurate bathymetry/accurate crest level in relation to sea level/ and engineered stability so they retain their shape, don't move around or subside. The thing to remember is "prefect bottom shape=perfect wave shape". That is why I'm proposing a prefabricated fully engineered reef structure. It is possible to engineer a stable reef structure on a sand seabed.

Ways to create surf breaks- There has been a lot of discussion of late in the Swellnet articles, comments, and forums regarding different ways great surf breaks may be created. So let’s have a look at a few of these ideas here. I will give you my opinion, and I invite others to make comment.
If we are going to deliberately create surf breaks, then the method/tech used needs to be practical, provide the best outcome for the $ outlay, be adaptable to common situations, and be environmentally and aesthetically acceptable.

Breakwalls and groynes - let’s be realistic, no approval will ever be given for construction of breakwalls or groynes the sole purpose of which is to try to create surf. The same can be said for artificial headlands which are just broader versions of the above.
Gold Coast City Council originally proposed a pair of artificial headlands for erosion control at Palm Beach, Gold Coast, then scrapped the idea following resident backlash in favour of an artificial reef with sand nourishment. This was due to the impact these headland structures would have had on the aesthetic amenity of the beach. Breakwalls have also been suggested as an option for the protection of Belongil Beach, Byron Bay but again no-one wants to see any structures, whether they be breakwalls, groynes, or exposed seawalls built on beaches. This is why artificial reefs, which are invisible, have great potential as a solution for coastal protection.

Submerged “simple” groyne-like structures have also been suggested on Swellnet to trap long-shore sand drift in order to try to create better conditions for wave breaking at that location. In extreme erosion or accretion conditions cross-shore sand movement can alter the seabed level, if we are talking Gold Coast say + or – 2m, and the shoreline location can vary considerably, so any structure like this will need to be much deeper/longer/wider and more heavily engineered than you may think to remain intact and still continue to trap long-shore sand drift- definitely not “simply” a few placed sandbags, rocks, or a row of submerged posts. How effective or reliable this idea may be in improving wave breaking is uncertain, so the cost/benefit may not be there. Anything that relies on a shifting sand seabed to provide correct bathymetry for wave breaking is bound to have its limitations. Best to spend the effort/$ on a reef that sits out further and has the correct accurate bathymetry all of the time. Also, placing any structure just under the water surface along the shoreline will be a safety issue.

Outer artificial reefs to refract swells into inshore peaks- yes, we see this effect occurring naturally, but the broad and shallower outer banks/reefs that interact with incoming swells, i.e. slowing wave speed/reducing wavelength/increasing wave amplitude, inducing wave refraction, are very extensive, so the cost to try to artificially reproduce such a broad scale setup is prohibitive. Again, best to spend much less effort/$ on a much smaller reef structure, or multiple reefs, with the correct accurate bathymetry for waves to break directly over them.

“Re-contouring” existing coral reefs or rock platforms- It is also suggested by some that this could be a way of creating surf breaks. In theory, if the correct accurate bathymetry could be formed waves will break accordingly. However, these areas are protected habitats (or should be in all jurisdictions), and no disturbance of coral reefs, rock platforms, or other natural features should be permitted anywhere. This is why off open sandy bottom beaches are the preferred sites for the Offshore Surf Reefs concept.

Geotextile sandbags, rocks, or any other collections of individual units- these things have all been tried by others to create surfing reefs, with varying degrees of success or failure. The latest by Gold Coast City Council at Palm Beach was attempted using GPS placed rocks. All of these suffer from the same problem- the correct design bathymetry and reef crest levels cannot be built accurately enough. The exact design bathymetry and reef crest level in relation to Mean Sea Level (MSL) needs to be attained to create perfect waves. This is why a fully engineered, prefabricated reef form is used for the Offshore Surf Reefs concept.

My colleague, Wayne Bartholomew (ex CEO and President of the ASP), and I both share the vision of creating “World Class” artificial surf reefs, and in conjunction with the Griffith Centre for Coastal Management, Griffith University, Gold Coast, have for some time been advocates of a constructing a trial reef in the Gold Coast/Tweed area. We are currently seeking private investor/s for the trial project.

www.offshoresurfreefs.com