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Why have most geotextile artificial reefs never really worked?

News | June 7, 2023 | By:

Artificial surfing reefs are a technology that has come with a lot of hype, but famous failures such as Boscombe in the United Kingdom have made man-made reefs the surfing equivalent of Don Quixote tilting at windmills. Time and time again, we’ve seen hopeful coverage during the planning stages, only for the projects to go over budget, take forever to build and flat-out not work. The consistent failure of the artificial reef has led some experts to claim that the very idea of a working artificial surfing reef is a myth. So why is it that these reefs seem to never work?

In looking at the history of the artificial reef, one acronym comes up again and again: ASR. In the 2000s, ASR was the go-to company for artificial reef design and implementation. If anyone could shed light and give insight into artificial reefs, it’s them.

“In the mid-90’s, Shaw Mead was doing his thesis in environmental science and marine ecology when he met Australian surfer and University of Waikato professor Dr. Kerry Black,” reported Newsroom in a profile on the company. Together they established Amalgamate Solutions and Research (ASR). ASR and its founders have had a hand in the most high profile attempts at artificial reef creation, as well as the most public failures: BoscombeMount ReefOpunake and Kovalam.

In addition, two other reefs not directly created by ASR bear its fingerprints. Narrowneck was a reef designed by Kerry Black and his students at the University of Waikato (including Shaw Mead). Narrowneck’s legacy is a little complicated, having been touted both as an example of failure and success. After it was first installed, the reef started to deteriorate, which prompted a $2 million renovation. It still stands today and there are studies that claim it has been a success in improving surfing waves, but Swellnet wrote that locals are reporting few surfable sessions and their camera seldom shows surfers using the reef. The other reef, located in Qamea, Fiji was a failed venture developed by Mead for the Maqai Eco Resort after he bought a quarter shareholding of the company.

Each of the projects were virtually identical – massive geotextile bags of sand were placed on the ocean floor, improved the waves a moderate amount, if at all, and then promptly fell apart. Richard Hatherly, who leased the resort on Qamea, amusingly referred to them as “giant dogs’ turds which never worked.”

In the case of Mount Reef, located in Mount Maunganui, New Zealand, they actually managed to create a hazard. “It’s also generated some unforeseen effects,” said Eddie Grogan of the Bay of Plenty Regional Council, “Including creating a large scour hole which affects waves and currents, increasing the frequency and intensity of rips which pose a serious risk to swimmers.”

When I emailed Shaw Mead about the track record of these reefs, he pointed to the geotextile bags as the main culprit. “Mega sand-filled containers were originally put forward as a construction method for artificial surfing reefs by coastal engineers in the U.S. and Australia because they were considered to be a more cost-effective construction method, a lower carbon footprint than any other method of construction, good substrate for marine organisms to settle on, ‘safer’ than rock or concrete and easier to remove.”

However, the fatal flaw of the bags was their propensity for failure. Shaw continued that while the geotextile reefs initially broke waves in the way that they were designed, “as soon as even a single sand-filled container broke and lost sand, the whole structure changed shape due to the fluid nature of sand – since the shape of the breaking wave is mostly reliant on the shape of the seabed, if it changes (i.e., the mega-containers adjust due to the loss of one or more of them), then so does the form of the breaking wave, which in the case of a surf break leads to a reduction in quality for surfing. The containers failed due to a number of reasons including anchors (Gold Coast), debris strikes (Kovalam), during construction with over-filling (Mount Reef), propellor strike (Boscombe), etc., etc.”

As a result, Shaw no longer believes in the viability of geotextile bags for artificial reef construction. “I undertook a critical review of the performance of sand-filled containers for MPR (multi-purpose reef) construction approximately a decade ago, which led to the change to traditional rock construction methods of the most recent MPRs built,” he wrote.

Mead’s reversal on geotextile sand bags as a workable method of reef construction is supported by other, non ASR reefs. In 2000, Surfrider built Pratte’s Reef (also known as Chevron Reef) in El Segundo, Calif., in response to the destruction of an existing break when Chevron built a groin in front of its refinery at Grand Avenue. The reef, comprised of large sand bags, never functioned and was removed in 2008. Long before that, in 1971, Hoppy Swartz (the first president of the U.S. Surfing Association) attempted to make a reef in Redondo Beach by placing bags of sand that immediately disappeared into the ocean floor. However, that attempt was on such a small scale that it is more of an interesting historical footnote than anything else.

The outlier of these failures is Bunbury in Western Australia. This was the first and only use of the Airwave design, an inflatable rubber bladder filled with sand, water and air. However, when the Airwave was installed in 2019, it immediately ripped open at the seam and had to be removed. There is still hope that the technology will work with improvements to the design, but the Airwave isn’t set to be reinstalled until 2024.

Geotextile sandbags account for the majority of attempts at artificial surfing reefs, and appear to have only actually worked once, depending on how who you ask about Narrowneck. It turns out that when one looks at the history of failure of the artificial reef for improving surfing, one is mainly looking at the failure of one type of technology. Furthermore, it is a technology that the industry of artificial reef design has since moved on from.

There is a small silver lining that shines out from behind the parade of failures. There are in fact instances of artificial surfing reefs that did not out-and-out fail. Cable StationBurkitts, and Palm Beach are artificial reefs in Australia that were created using stone instead of sandbags. At Cable Station, the Perth Artificial Surfing Reef Committee took large limestone rocks and placed them on an existing reef. At Burkitts, Greg Redguard lobbied the Beach Protection Authority of Queensland and the Burnett Shire Council to allow him to break down large boulders at the site and use them to fill in gaps in an existing reef. At Palm Beach (on the Gold Coast, not Florida), DHI Australia placed large stone boulders on top of a man-made sandbar (Shaw Mead also provided a design review for this reef). None of these locations were transformed into a world-class break, but each one had modest, measurable improvements in the quality of waves. There is one other artificial stone reef located in Borth, Wales, which was also co-designed by Mead. Its primary purpose was coastal protection, with surfing touted as a side benefit. While it succeeded in its main goal, there is little data one way or the other on whether it improved surf.

In context, the modest success of these non-geotextile reefs becomes more significant. If you chalk Boscombe and its brethren up as an expensive lesson in the flaws of sandbags, the success rate of the remaining artificial reefs is actually not bad. Nobody’s made a new Pipeline, but more often than not they’ve succeeded in their modest goals. In fact, one of the failures very well could turn the other way when the Airwave is hopefully re-installed next year.

It’s tempting to roll one’s eyes at every breathless announcement of a new artificial reef technology that promises to create a new world-class break, fix the crowding problem and revolutionize the world of surfing as we know it (in fact, a study co-authored by Mead noted that part of the perception of failure of reefs is a result of the “large discrepancy between expectations for the surfing waves on a particular MPR as compared to reality”). However, the optimist in me sees the quixotic history of artificial reefs not as a sign that it can’t be done, but a glimmer of hope that maybe it can be achieved now that we know to do it a different way. Article written by Cooper Gegan. Reprinted with permission from The Inertia.

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