An artificial surfing reef for Scarborough?

Stu Nettle
Swellnet Dispatch

Over the last five years, wave pools have been the last word in artificial waves. The number of companies working in the field has increased, each with their own patented spin on wave propagation, though only two have a working proof of concept, Wave Garden and the Kelly Slater Wave Company. No doubt the number of players will increase, and so will the number of ways to create a wave.

Curiously overlooked in all this has been the humble artificial reef. Twenty years ago the idea of forming a structure in the wave zone captured our imagination, it occupied the lofty space that wave pools now reside. Surfers, however, went cold on the concept after a string of artificial reefs failed to deliver.

But you can’t kill an idea and engineers by nature are persistent bastards. So as the wave pool pioneers scouted inland for cheap real estate, a few operators learnt from past mistakes, sharpened their calculations, and kept a keen eye on the wave zone.

Among those operators are Simon Mortensen and his team of surfers/engineers at DHI. Recently DHI have been commissioned to research the viability of an artificial reef at Scarborough Beach, Perth, and the team have modelled and designed a rock reef to work in Perth's low swell environment.

To read the full report click here.

Scarborough Beach with ideal conditions but lamentable shape - a product of uniform bottom topography

Three possible sites along Scarborough Beach were identified as potential locations. A final site was chosen, the decision based on access to local infrastructure, existing wave climate, and proximity to natural underwater features that focus swell energy. The final two points underscore the lessons that have been learnt from past artificial reefs. The new creed is natural augmentation - adopting a ‘working with nature’ approach.

The reef, if it gets built, will be located 200 metres north of the Scarborough Ampitheatre and it’ll assume a classic A-frame shape with a few critical improvements over past designs. For one, engineers now recognise that good waves take shape well beyond the takeoff spot. Wave heights are increased when swell focusses on a shallow point beyond the surf zone - think of an offshore bombora or seamount.

To that end, the Scarborough proposal starts with a conical ‘wave focussing toe’ designed to refract the incoming waves toward the centre of the reef. From there the reef has a left-hand arm running at 40° designed for intermediate-level surfers, and a right-hand arm running at 45° for advanced surfers. Each arm is 90 metres long and will offer rides from 40 metres to 120 metres depending on conditions.

Aerial view outlining the alignment of Scarborough Reef within a natural focusing zone and the proximity of the reef to Scarborough Ampitheatre

The ability to work in a range of conditions, particularly low energy conditions, is paramount, though the report states that during Perth’s infrequent big swells the reef “is expected to produce excellent surfing conditions of very high quality.” Reassuringly, at least for those who want some grunt, the design comes with a “potential increased risk of injury.” Who says we live in a nanny state?

No doubt legalities will be drawn up but at least the ambition is laid bare.

If it gets to construction stage, the reef will be made from granite placed into position by a barge-mounted excavator. It’s also been designed so that the cost of the reef is proportional with the volume of rock required. A smaller budget will fund a smaller version: the same reef, positioned in the same location, in the same water depth, but shorter arms and hence shorter rides.

With all the research now done the agencies involved are canvassing the surfing community. If you’ve read this far please take a moment to answer the questions below.

Want to read more about the reef? Click for DHI's Feasibility Study

Comments

indo-dreaming's picture
indo-dreaming's picture
indo-dreaming commented Friday, 20 Oct 2017 at 8:29am

As much as i love Kellys wave, i still like the idea of artificial reefs more, if Kelly can create a wave like that in a pool surely they can start creating decent artificial reefs.

I guess it just needs more scientific kind of study rather than just throwing some concrete in the ocean and hoping for the best, which looking at this looks like they are going down the right track.

ssurfzup's picture
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ssurfzup commented Friday, 20 Oct 2017 at 7:10pm

If anything can be learnt from the Gold Coast's Narrowneck reef it is perhaps not so much sand build up around the artificial reef as much as the artificial reef settling into the sand its on, if it is not constructed on existing reef. In an A frame situation it may well be beneficial to also construct what I would call tracking reefs seaward of the artificial reef to pull the predominant swell to the appropriate spot???

Mort's picture
Mort's picture
Mort commented Saturday, 21 Oct 2017 at 1:18am

If Tim Winton is cool with it, I am cool with it.

Mort's picture
Mort's picture
Mort commented Saturday, 21 Oct 2017 at 1:19am

I am cooler than Tim Winton, that bastard!

Mort's picture
Mort's picture
Mort commented Saturday, 21 Oct 2017 at 2:08am

I am going to write a storie, I will.

Robin Masters's picture
Robin Masters's picture
Robin Masters commented Sunday, 22 Oct 2017 at 11:45am

Don’t forget Twiggy Forrest. You’ll have to run it by him as well

Mort's picture
Mort's picture
Mort commented Monday, 23 Oct 2017 at 11:27pm

Who is Twiggy Forest when he is at home? Is he Tim's secret boyfriend? Lookout Tim, I am going to out you! I am such a sand dweller, when I say that.

belly's picture
belly's picture
belly commented Friday, 20 Oct 2017 at 8:45am

Wouldn't sand build-up around the reef be an issue?

Noel's picture
Noel's picture
Noel commented Friday, 20 Oct 2017 at 10:07am

the report acknowledged sand build-up in the sense that it will produce a near-shore buildup (salient response) in the lee and a reduction (scouring) to the north. Page 5.
However, one benefit I would expect to see is the formation of beachbreaks in the nearshore zones which work on lower swell conditions. This will be the extra bonus for Perth surfers as the sandbanks are typically close-outs.

bill-poster's picture
bill-poster's picture
bill-poster commented Friday, 20 Oct 2017 at 9:11am

I agree Indo Dreaming, artificial reefs always seemed like a fantasy, though not as much as wave pools, and now wave pools are a reality. So?

Belly, I don't think Perth sand moves like the east coast and vicco. There aren't really rips and gutters

Noel's picture
Noel's picture
Noel commented Friday, 20 Oct 2017 at 9:40am

One development on artificial surf reef past efforts is that through wave-pool projects its been proved that the bathymetry required to produce a credible wave shape can be understood and replicated on demand. Evidently Kelly & Co have arrived at the best formula but whether they will share that knowledge is a different story. I would be surprised actually.

stunet's picture
stunet's picture
stunet commented Friday, 20 Oct 2017 at 10:09am

You're right that Kelly's pool shows how bottom contours can be better understood, however you can't use his bottom shape as a guide. There's very little overlap between the hot tub and the real world. For one, Kelly uses soliton waves, solitary waves that come from a fixed angle with no interference of any kind. They shape their bottom contours purely for that single wave.

Bathymetry in the ocean has to accept waves of various period, direction, and size, so there's many more variables that have to line up before good waves are achieved. I don't think it's impossible, like I said, knowledge across the board is advancing. However, a reef that creates good waves in the ocean probably wont bear much resemblance to one in a wave pool.

Noel's picture
Noel's picture
Noel commented Friday, 20 Oct 2017 at 10:26am

the research that produced their evidently very successful results will have demanded mastery of a broader base than just pool bathymetry.

So the wider implications of my comment still remain valid, in that the ability to recreate surf-able waves is now in Beta version and a reasonable certainty.

cgrover's picture
cgrover's picture
cgrover commented Friday, 20 Oct 2017 at 9:41am

The same idea for the coast South of Adelaide - like Middleton Point and the area around it has been mooted by surfers for years. The local council and the SA Govt have shown no interest at all - they'd rather have a tuna viewing cage which will potentially attract sharks and reduce the number of surfers and other people in the water. (Port Lincoln moved the cages from Boston Bay in part because of unwelcome visitors) I can just imagine the economic impact of a few shark sightings on a town reliant on a huge summer influx of visitors!!

Hucky's picture
Hucky's picture
Hucky commented Saturday, 21 Oct 2017 at 10:29am

How bloody true.
Local gov have been bought out by the big boys in the tuna game.
Shame on the Labor state and the local liberal man for not caring about this issue.

P.s More help sinking this floating trash cage was needed a year ago.
The media on many levels all went very quite when “WE” people that swim and surf the local area were having a say over this complete madness.

A couple of whitey bights and look at the home prices drop.

Hard to surf with a leg or arm missing???

Anyhow. A reef that’s not a reef.
More trash is water???

Hucky..

Hucky

radiationrules's picture
radiationrules's picture
radiationrules commented Friday, 20 Oct 2017 at 10:09am

seems like such a more naturally sensible idea. there is an artificial reef at Cable Stations in Perth, which has very good waves if the ground swell exceeds 2.8m; which is very rare. I was told my marine & civil CEO that built it that the client wanted to read the bathymetry in a different way to the builders, which lead to the new reef being 50cm lower than intended by the designers, so that's a crucial factor in surfable days too. I'd imagine 20-50 awesome winter days at 4-6ft is better than 20-50 improved summer days at 1-3ft. I don't think you can have both?

Noel's picture
Noel's picture
Noel commented Friday, 20 Oct 2017 at 10:39am

interesting to hear the real reason why it hardly breaks. Makes perfect sense now.

That half metre has made all the difference. Would have been a reasonable success otherwise.

The other thing I dont get is why they build so far from the beach. Not many people want to sit that far from shore, especially on inconsistent days.

geek's picture
geek's picture
geek commented Friday, 20 Oct 2017 at 10:45am

It was built on top of an existing reef (that would break on the biggest of swells) I believe

yocal's picture
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yocal commented Friday, 20 Oct 2017 at 12:07pm

Its interesting that this particular Cables reef is the only one being called out as being successfully stable, and that it is build over limestone, whereas all the other failed geotextile reefs are noted to have been constructed over sand.
My understanding of the failures is that the materials sink (and move) over time as the sandbottom gets displaced. There must be some significant math involved to determine how much rock would need to be added that is intended to settle and 'sink' below the seafloor to stabilise or 'float' the visible rock which shapes the reef above the sandbottom. Kind of like how an iceberg rests at the water level - the majority of the ice being below the surface. I couldn't see anywhere in the report that explains how this is done, but i'm guessing its in there or at least in the calculations.

Go deeper Taylor, go deeper!

radiationrules's picture
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radiationrules commented Friday, 20 Oct 2017 at 12:55pm

interesting thought yocal..and as you point out the cables reef setup is granite lodged into an existing reef structure, whereas scab's is going to be granite on sand. I'm no engineer; but the thought I had as why granite, why not limestone rock on limestone bedrock? I'm not quite sure why that's not the option - it must be significantly cheaper? Maybe its more likely to float off? My next thought was gnarly little limestone reef outcrops along the coast, wit the main reef, re-furbished every few years. Sound good to me? More bang for your buck than 1 lump of granite? Maybe there's an oceanic engineer out there that can set us right.

stunet's picture
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stunet commented Friday, 20 Oct 2017 at 2:34pm

Limestone is an option, RR. It's noted in the Feasibility Study. Check the links in the article if you'd like to find out more about that aspect.

radiationrules's picture
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radiationrules commented Saturday, 21 Oct 2017 at 10:20am

thanks stu - very informative read that doc.

Noel's picture
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Noel commented Friday, 20 Oct 2017 at 2:47pm

the typical limestone you can get from a quarry is too soft and way less dense than granite. It could potentially get chucked around in a severe swell event. So for fully submerged I recall something about granite or granite capping being preferable.

neville-beats-buddha's picture
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neville-beats-buddha commented Friday, 20 Oct 2017 at 10:25am

So have the designers geared it towards windswell or longer period groundswells??
Despite what people think we get groundswells here in Perth, theyve just been kneecapped by a few kilometres of shallow water.

Lanky Dean's picture
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Lanky Dean commented Friday, 20 Oct 2017 at 10:43am

The wave on the home page for the article looks pretty fun ? Is that Scarborough? Does perth suffer from swell blocking/ dissipation from outer reefs ?

geek's picture
geek's picture
geek commented Friday, 20 Oct 2017 at 10:47am

Yes suffers big time. Rottenest, Garden Island, offshore reefs to the north all work against it. Remove all of that and Perth would be good year round like Margs

Lanky Dean's picture
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Lanky Dean commented Friday, 20 Oct 2017 at 2:40pm

Thanks geek !

Tele's picture
Tele's picture
Tele commented Friday, 20 Oct 2017 at 12:04pm

The artificial wave off Cables is excellent. It did take years of R&D but I believe its the only designed reef that behaves like it was meant to. Obviously it does take a lot of swell to crank but when it does its a perfect wave. Geo bags have failed many times with other reefs and granite like the Cables works best and has only got better with time. For a first time reef its 5 stars. If they could build reefs that work from 0.5m swell then it would truly be a amazing. Cables reef needs a swell plus of 1m and a low tide. Hope ti happens.

chooky's picture
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chooky commented Friday, 20 Oct 2017 at 12:29pm

One of the problems with A frame artificial reefs I have encountered over the years is that they have a small take off area that can be dominated either by locals or experienced surfers so the break doesn't get used that much by inexperienced or weaker surfers especially during a good swell.
How will the design deal with this problem?

stunet's picture
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stunet commented Friday, 20 Oct 2017 at 12:33pm

It's configured so the peel angle is less on the left than the right. So the left is for less experienced surfers, and the right is for better surfers.

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 3:25pm

Why do the naturals get the good wave! I'm a long suffering goofy local of Perth and am all over this like a rash. Me and a mate have long wondered how to improve the banks and was only chatting to a fella out at Scabs this morning about it. I recall a Volcom comp they held about 15 years ago right about where the proposed reef would be located. The weekend before the comp I noticed a bulldozer pushing a small point of sand out into the water and the following weekend when the comp was on it was pumping, 2 distinct banks one to the north of the little sand spit and one to the south. I'm guessing it had something to do with the disruption of the longshore flow back out to sea causing channels through the bank that generally runs from Trigg Pt to south of Brighton...yes people one long stretch of closeouts. I've often wondered why they couldn't try this up and down the beach every 200m or so...cheap and potentially effective but obviously not long lasting.
Perth needs this desperately, and more than just 1. I hope it comes to fruition soon.
BTW I can't subscribe to the fact that the Arti reef is good...maybe once a year, I drive past it a lot...it's super fickle and really only has a right when it was supposed to have both a left and right. Definitely doesn't produce what it was designed to produce...my call epic fail.

Legrope's picture
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Legrope commented Friday, 20 Oct 2017 at 12:30pm

I agree that Cables does crank when it's on as I've had a few sick sessions out there but the planets need to align before that happens which is only a couple of times a year. Just a poor location to pick up swells. Still would easily be the best wave in Perth, shape wise. Scarborough would be good but it will probably mess up the sand flow for Trigg point summer bank. (Might also make it better?)
There are so many options just north of Trigg with reefs needing a bit of enhancement to come good as they're full of holes. Less sand flow to worry about as well. But for Perth surfers we'll take bloody anything. Just put it somewhere between Scarborough and Watermans! Do more than 1. Be like Kelly and experiment. Can't make it any worse..

Halfscousehalfcockneyfullaussie's picture
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Halfscousehalfc... commented Friday, 20 Oct 2017 at 1:29pm

Can't whinge about improvement of a wave, be interested how it turns out

Cookie1's picture
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Cookie1 commented Friday, 20 Oct 2017 at 2:57pm

Been surfing Scarbs for over 30 years and that looks like the location is the Manning St bank , one of the more consistent banks in that area. Best place surf wise is about a kilometre south around Hale Rd. We used to call it "Meats Beach" but I can't remember why. There must be a small swell window in this area as it is consistently bigger than Scarbs but almost never has any banks. Put it there I say - there is reasonable access and will help thin the crowds.

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 3:34pm

I agree Cookie, the stretch between Floreat Groyne and Brighton can be the testing grounds for all sorts of different reef setups. Gets lots of swell but is usually garbage. w ehave the conditions just not the banks.
My call for the villain that has ruined Perth's northern beaches surf...and Leighton for that matter...is the restoration of the dunes, that has fucked everything, rip those out and see what it does.

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Whoee commented Friday, 20 Oct 2017 at 4:55pm

Agree with Cookie and Quokka. Have been surfing that stretch for nearly 30 years. They've selected an area that always gets a decent bank in winter. The fact that there's a bank in the same place every winter shows there's something underlying the spot. Plenty of nothing ground between Floreat and Brighton to test without ruining an existing spot. Between North Scarborough and South Trigg would be even better as it gets more swell.
A mate's dad who's been surfing since the early 1960's reckons there used to be bits of reef out the front of Scarborough, but were blown up back in the day. I've whacked my shin on a limestone ledge in the shoreline gutter at north scarborough after a winter storm, so there's definitely something underneath the sand in the area.
Not keen on using rocks to try find a solution. Use biodegradable sand bags to see what works and if it doesn't, they'll dissolve in a few years anyhow. Grab say 1,000 bags, call on the surfing community to come down and fill them, and place them into the lineup. You'd have your first artificial break for less than $20k. Find a successful design, and then put something permanent in.

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 5:07pm

Amen to that Mr W. Faster and much more cost effective. I'm also all for moving it to the Contacio stretch, or Thirds. There's definitely rock at Thirds, they wack a sign up every now and then to warn people of it being exposed during winter. the Scabs location will impact too many beach goers I recon it will be carnage during summer if there's any swell plus, as has been raised, this is basically the only place that gets banks during winter. From what I've seen when man messes with nature it virtually never goes well...apart from the Superbank of course!
I reckon anything that disrupts the northerly flow of sand caused generally by the prevailing SW wind and associated currents plus causing sand aggregation against some sort of structure has to be a good thing. We only get banks along this stretch when we've had sustained NW'ers during winter as these counteract the prevailing SW'er that blows all summer and the effect this has on sand movement. The Trigg boys love the Freo doctor as it gives the Point a bank which is the only rideable wave during summer.

Whoee's picture
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Whoee commented Friday, 20 Oct 2017 at 5:23pm

100% agree. Just need some people with some common sense to allow it to happen. Unfortunately common sense isn't very common amongst the govt departments required to rubber stamp it. Plus, i'm sure some people just love being able to say they've approved a $x million dollar project. Keep it simple, make it easily reversible, and get the scholars to validate the anecdotal observations and design ideas of those (surfers) who have been keeping an eye on the sand flow and waves of the area for decades. Just think, we could build 100 $20k surf breaks between floreat and trigg for $2 million, as opposed to one hyper-politicised break that probably won't work properly anyhow.

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 5:26pm

Govt, especially local, is devoid of common sense.

Whoee's picture
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Whoee commented Friday, 20 Oct 2017 at 5:34pm

Yep, City of Stirling are hopeless.

Stilagrom's picture
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Stilagrom commented Saturday, 21 Oct 2017 at 1:22am

Your mate is right Whoee,
My grandmother & her sister were 2 of the first female lifesavers at Scarborough. She told me on more than one occasion they blew up the reef that was at Scarborough as it was deemed a swimmers beach, that's why Peters still has a wave in summer from the limestone cap that exists under the sand. Back then to get to the secret spot of Trigg Point you had to go back inland to the Nookenburra then back out to the coast.
Interestingly there is a document in the state library penned by the same genius that proposed a water pipe to the gold fields, C Y O'Conner. His observations of the WA coast over 100 years ago and in particular the swells is incredibly accurate even compared with today's data. Swells on the west coast over 1.5m drag sand away from the shore line due to their action and under that magic 1.5m it pushes it forward, which is why we get much better banks along the coast in winter (plus the swell gets in unobstructed from the north rather than the south).

This begs the question what the F#$% those cretins at the Scarborough surf lifesaving think they are doing by "grooming" the beach and pushing a wall of sand up to the waters edge in winter. Put simply, the beach will wash away in winter and be replaced in summer from the small South westerly swells. No wonder the sand never looks lean any more. But what do I know, I'm just a 44 year old grommet who's been surfing that strip in front of Peters for the last 30 years!

Perhaps rather than a reef per-say, we need to look at some underwater redistribution of the sand to focus the swell into certain spots. This will have the dual effect ofnot only creating a much larger wave for the swell size but also making the clubbies happy to have more beach as the waves will loose their energy further out to sea and reduce beach erosion due to high swells!

velocityjohnno's picture
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velocityjohnno commented Tuesday, 24 Oct 2017 at 8:52am

Good post grom,
We have pics from father in law's surfing at Scarborough in early 1960's and the waves look far more A frame, breaking further out. (Still have his boards in my wife's family, beautifully restored.) I was also told by the old timers that before North Mole, the Sandtrax area was beautifully shaped little beachies. Very old footage of Fremantle harbour reveals a large reef immediately in the way of the entrance, which was blown up. Agree that grooming winter sand is silly.
& also, nobody's mentioned Leighton - in winter this was my preferred beachy as it had shape (90's through early 2000s before I left) and barrelled quite a bit too. Mark Warren's surfing atlas mentioned it as 'Perth's version of Duranbah' so it must have been OK in the 70's as well. How is it today, with the carparks filled into the surfclub? Has it changed? Does it still break in winter?

quokka's picture
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quokka commented Tuesday, 24 Oct 2017 at 12:41pm

Mentioned Leights briefly in a previous post but yes it used to pump and I've lost count of the memorable sessions I had out there during my lost uni years,it was definitely my go to beach and a bit of a well kept secret amongst the south of the river crew. Now I lament it's passing which again seems to be due to humans messing with sand flow. The extension of Nth Mole and construction of Rouse Head completely screwed with the sand flow and then the greenie dickheads went and artificially stabilised the dunes. Someone didn't like the carparks and road getting covered with sand so the council obviously gave them cart-blanch direction to "fix" the problem. The dunes the whole way along the Perth coast have been artifically stabilised to the detriment of Perth surf quality. Portable sand dredgers like the ones used on the Goldie, to replenish sand to the southern Perth beaches and let it flow north is also a viable option. Let's take a moment to also pay our respects to Cott main, the best left in Perth...R.I.P.

How do the greenie groups get approval to plant out the dunes whilst surfers who raise the point that these practices are more than likely ruining our surf are never listened to?
How do surfers become a vocal minority?

Let the sand flow you council bastards!!!

Stilagrom's picture
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Stilagrom commented Tuesday, 24 Oct 2017 at 1:05pm

I completely Agree Quokka,

I lived in North Freo for 7 years and surfed Leighton only a hand full of times ( it's better at sand trracks where you can get a small wave rebound off the rock wall for a little double up) but it's never as good as mates have told me that lived in the area as grommets.
Unfortunately the sand flow is the main culprit (or lack of).
C.Y. O'Conners document I referred to previously also states that in WA due to the speed of the swell that any groyne's to stop erosion should be long and skinny as wider groynes due to wave action done catch a comparable amount of sand. So next time you pass by City Beach and wonder why there is no banks that's the reason... they widened it ages back when they put the tower in and that stuffed it, even the south side winter wonderland doesn't work like it used to anymore.
Poor Perth surf, stupid unqualified idiots that now want to put in reefs to solve a problem people just like them created in the first place!

quokka's picture
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quokka commented Tuesday, 24 Oct 2017 at 2:14pm

Hahaha bang on Grom, gotta love a capitalist society, these dickheads are all about feathering their own nests!
The last good surf I can remember at Leights was 2002, the right about 100m north of the surf club pumped, stand up pits...not that I got any as there was hungry mob! You're probably right about Sandies these days, I've only checked it a few times on bigger swells but it was pretty rubbish when I did, I'm sure it can get decent waves but again there is no beach there anymore and the banks are not what they used to be. Really sad to be honest and I'm concerned that I won't see good surf in what remains of my surfing lifetime in Perth. Unfortunately it means chasing waves 1-3 hours out of Perth which is tough when you have billy lids playing sport. I'd like to give the f#$*wits that decided to make all these changes the grom treatment, i.e. tie them to a pole and smear shit all over them...yes I'm annoyed.

velocityjohnno's picture
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velocityjohnno commented Tuesday, 24 Oct 2017 at 8:03pm

Good call on Leighton being a bit of a SOR secret spot when it's really NOR - 97 thru 2001 I was living Curtin Ave but working Myaree after growing up SOR, and Leighton would be on the drive home. Managed to negotiate early start early knock off with boss, and would get that last hour in the water in some really nice hollow waves quite a bit. I'd get home to the Mrs with kids hanging off her, in dripping wetsuit (Kingswoods and vinyl seats/rubber floor mats you see...) and say "Another hard day at the office..." To which I might get a bit of a scowl, and the kids saying "Do you surf for work??" Fun times. It was a really fun break.

Perth could be so good, maybe one of the funnest capitals to be a small wave surfer, if only we decided to engineer the coastal landscape in favour of waves. We've engineered it for everything else it seems.

quokka's picture
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quokka commented Tuesday, 24 Oct 2017 at 11:19pm

That’s funny, to be honest I had to think hard about it being NOR. All the fellas I surfed there with and knew that surfed there lived SOR. The NOR fellas all surfed Scabs-Trigg and only occasionally ventured south when the swell was too big. Yes good memories, sad loss.

Robin Masters's picture
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Robin Masters commented Friday, 20 Oct 2017 at 10:11pm

Good point Cookie. Put it further south towards Floreat . Floreat would probably crank in winter if it had a reef

Quentinc4589's picture
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Quentinc4589 commented Friday, 20 Oct 2017 at 3:47pm

Hi does anyone know who commissioned this study ? Was it local govt or state govt ? Surfing WA ?

stunet's picture
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stunet commented Friday, 20 Oct 2017 at 3:53pm

Quentin, the study came direct to us from DHI, and it's all we have on the project. When more info comes to light - RE funding - we'll post it on Swellnet.

nogo's picture
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nogo commented Friday, 20 Oct 2017 at 3:47pm

Just pump some sand like they did in QLD, and do it four or five spots to spread out the crowd.

Halfscousehalfcockneyfullaussie's picture
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Halfscousehalfc... commented Friday, 20 Oct 2017 at 4:22pm

If they do get it right, could be a good precedence

simba's picture
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simba commented Friday, 20 Oct 2017 at 4:37pm

Well looks like a lot of time and effort has gone into this study and i hope they get it off the ground and it works...pretty impressive on paper that's for sure.Sometimes simple things can work in collecting sand ,as in Coffs when they were doing the ocean outfall pipe and the structure of a wharf type set up to install the pipe created banks which would build up around or nearby the pylons and some really good waves were created.When it was finished and the structure pulled down the banks pretty much disappeared .I recon if you drove pylons into the sand and have them stick out of the sand, height depending on depth of water you would get sand build up.Doesn'tt take much to collect sand and they could and do them in a variety of potential shapes.Pick the right beach,probably would need good sand flow etc but it would have to be a quick cheap option.

simba

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 4:46pm

Reading the report this is a way off unfortunately, a lot more work needs to go into it, the most being environmental impact. The beach erosion either side would be my concern as the beach along that stretch is now extremely narrow due I reckon to the bastard stablised dunes. Not to mention the $16.9M pricetag, where's that coming from?
I with you Simba, something that gets to market quicker and cheaper in the meantime while they continue to research this option is what we need. Get the dozers out City of Stirling and start ploughing! Trying something now has to be better than the shite we have to deal with on a daily basis.

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Cookie1 commented Friday, 20 Oct 2017 at 6:13pm

Cables works well but unfortunately doesn't work very often. Right place to put in terms of an existing reef but wrong place for swell. Like the idea of numerous smaller, cheaper ones south of Scarbs where there is a bit more swell. Let's face it, on a really good day this artificial reef is going to be packed on an already crowded coastline, why not spread the love and the crowds down the coast.

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 6:51pm

Bang on about the crowds cdawg. This is only going to make them worse. I'm with you about spreading the love, so much coast that could be surfable but just isn't.

matt.lennon14's picture
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matt.lennon14 commented Friday, 20 Oct 2017 at 6:41pm

the major issue with Perth surf was always no swell. But at least they won’t have to wait for a storm to create a decent bank. Unfortunately, expensive bank won’t make much of a difference to surf

quokka's picture
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quokka commented Friday, 20 Oct 2017 at 6:52pm

We get enough swell and good conditions...banks no.

Koura's picture
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Koura commented Friday, 20 Oct 2017 at 6:56pm

This proposed reef would mean trigg point would never get enough sand. Then of course they could just fill in the point with granite and make it a better wave.

Whoee's picture
Whoee's picture
Whoee commented Friday, 20 Oct 2017 at 8:03pm

I reckon the sand would still move along the shoreline. The proposed break appears further out than where the waves currently break, providing a gap between the proposed reef and shoreline. My concern would be during a summer sea breeze, the northerly flow of water (which carries the sand to Trigg point) would increase in velocity through this gap. What would happen north and south of the proposed break location - scour or buildup?

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ssurfzup commented Friday, 20 Oct 2017 at 7:25pm

I just tuned into this! Is it so much the sand settling around the artificial reef or rather the artificial reef settling into the sand around it(remember Narrowneck) if the artifical reef is not built on existing rock? I have often thought of what I call tracking reefs being built seaward of an articial reef to funnel swell of inconsistent direction onto the right spot - especially in the case of an A frame artificial reef??

homer75's picture
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homer75 commented Friday, 20 Oct 2017 at 7:46pm

Good read guys. I'm moving back to Perth from the East coast, this would be a plus in any form.

morg's picture
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morg commented Friday, 20 Oct 2017 at 8:04pm

Simba has a good point. Over the years I can recall a few great waves caused by things just stuck out off the beach that allow sand banks to develop. Eg water out flow pipes, temporary jetties, groin, a boat that ran aground, Burwood beach sewer outflow, breakwalls etc. Maybe the simple approach is worth trying while the environmentalists and politicians work out what they are going to allow.

Perhaps Swellnet can have a forum on man made or storm created beach obstructions that have created sand banks and good waves so we can learn what the best options are.

ssurfzup's picture
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ssurfzup commented Saturday, 21 Oct 2017 at 1:01pm

In 1993 the sewerage outfall pipe at Belmont Beach near Newcastle was extended and taken approx 3km out to sea. During construction a 300m long prefab pier was erected and sand pumped of it into the water as the work went on. We had a fanastic year of waves on both sides of the pier ............ the work finished and they pulled it down!! This pier helped to fuel my obsession man made waves.Have fotos if anyones interested

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rablex commented Friday, 20 Oct 2017 at 8:21pm
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rablex commented Friday, 20 Oct 2017 at 8:34pm

what happened to this place

Noel's picture
Noel's picture
Noel commented Saturday, 21 Oct 2017 at 12:34pm

seems to have been a failure, based on the info I could find a few months back on the internet. might have deteriorated somehow, ??? Seems to have been a lot of blame and finger-pointing in media commentary locally. Partly because the funding was post-tsunami rebuild and funding seems to have been diverted to the reef build. Controversial.

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velocityjohnno commented Friday, 20 Oct 2017 at 8:25pm

Read with interest. Swellnet has already done articles on dune stabilisation destroying beachies (thanks Marram grass) and relative sand flows between QLD (500,000t/yr) and WA (50,000t/yr).

Tread carefully with sand flows in WA, sand starvation to the north can be pretty rough - eg Gero Marina to Bluff Point, Bunbury Jetty and (before my time) the North Mole in Freo. Eventually new waves develop - eg Sandtrax.

I can remember Surfs before the suburb went in, a lot more A frames, then afterward a lot more closeouts except for the turtles area, which seems to have some form of rock underneath and thus a bit of shape, if smaller size. Lanno was always OK as no development in the back beach, and up to Wedge better as no development at all.

Speaking of rock underneath, this is the key to pretty impressive long shapely rides on beachies like the 13th stretch, a very different setup to Perth.

Very interesting to read about the bulldozers setting up a bit of jutting sand at Sacrborough before a comp that produced shape. Maybe the true solution for the place is like a ski resort - get 'aqua groomers' into the sand at night. Or at least stop grooming the sand completely parallel flat to the coast!

velocityjohnno's picture
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velocityjohnno commented Friday, 20 Oct 2017 at 8:29pm

'Bunbury Jetty' should read 'Bunbury Port' ie the extensions, my bad

GreenCT's picture
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GreenCT commented Friday, 20 Oct 2017 at 8:34pm

Having lived around Mandurah for a long time twice council were convinced as part of sand replenishment programme to dump about 2/5 of the sand in a spit in the top corner of a north facing bay.

The result was we got some amazing little left handers for the micro groms and suddenly of an afternoon there were 20 or 30 kids, mums dads all out there. It lasted about a month. For this bay to have the some of the sand they punp at the Dawseville cut boosted and pumped to here would create a great left for the groms, offshore in the SW wind and it would br bringing back the sand that naturally came pre the Dawesville Cut days.

I also wonder if when the excavate sand at the beach known as Pyramids south of the cut if they did it in sections rather than starting at one end then the ocean trying to fill in where they are taking sand would create banks.

Maybe instead of the huge cost of this up front reef could you not just invest in something that moved sand off the beach into a slug that could be regenerated. Dig a lagoon put the sand out the back.

I also wonder why instead of rock we should not look to what tchnology the oil and gas industry has already to deal with scouring around pipe lines.

In stead of rocks why not a large blanket signifcantly pinned with hair brush style fronds that exist already to capture and hold sand.

The fronds would be sculptured to a height to create a right and left offshore and then once it has filled to capacity the sand would keep moving on.

No rocks, no reef just a system that doesnt act like a groyne but just a capture of a quantity of sand.

I would think the cost of this would be far less than trucking rock and by adopting the existing anti scouring technology and having blanket coverage rather than rocks that will if over sand move and drop.

bish's picture
bish's picture
bish commented Saturday, 21 Oct 2017 at 11:18am

"In stead of rocks why not a large blanket signifcantly pinned with hair brush style fronds that exist already to capture and hold sand"

I like this idea, similar to snow fencing. Do you mean that there's actually an existing product??

Bish

da-duke's picture
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da-duke commented Friday, 20 Oct 2017 at 8:42pm

https://www.dropbox.com/s/611eqm826dw8ldv/scabs_artificial_wave_lineup.j...

Not the exact location which is approx 100m north. Trestle's peak used as a set up.

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mackadog commented Friday, 20 Oct 2017 at 9:27pm

Fucken stupid idea create another trigg point now 20 or 30 bulky bags in a simple v shape 5 @ time filled with sand when they break they break dump me off a jet boat on micro days ( not many of them in Perth ) be mini groins that will pull in sand spread from meats to grey skulls do it in autumn let the fun begin 5 peaks that would break up straight handlers !

f

steveb's picture
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steveb commented Friday, 20 Oct 2017 at 11:05pm

Stu .. do I detect you moving away slightly from being a confirmed artificial surf reef sceptic?
Its always good to see a new surf reef being proposed...this is my take on the Scarborough proposal-
With a small wave climate, such as at Scarborough, it is very important to have a very accurate bottom shape combined with a relatively shallow reef crest to produce consistent quality waves. I doubt rock can be installed accurately enough , + or - 500mm would be about the construction tolerance I reckon, plus rock would probably be subject to differential settlement as well, quarried rock is lumpy and cannot form a uniform surface. User safety is a critical design consideration.. quarried rock will produce a very rough reef surface with dimensionally uncontrolled spaces between the rocks likely to contain numerous possible entrapment points. Quarried rock will produce an inherently hazardous reef surface, i.e. be a known hazard intentionally placed in relatively shallow water, a hazard that cannot be ameliorated. A user safe reef design needs to have a smooth even reef form without any possible entrapments or pointy protrusions.

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truebluebasher commented Friday, 20 Oct 2017 at 11:21pm

When you're done re-modelling those pitch perfect A Frames could you send a few back east to restock our GCCC trawled WSR beachies.
WA skegz must dine at Huey's table to be tossin' their basherz those mighty decent scraps.

Am I reading this right? WA skegz are about to redevelop this shit hot A Frame?
GCCC would need to stuff up 20 surf reefs before they fluke that A Frame. (Not a joke).

Channel bottoms's picture
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Channel bottoms commented Saturday, 21 Oct 2017 at 8:28am

Perth gets enough swell, particularly from Hale Road to Trigg Point, to make something of an artificial reef. Agree that it is much smaller than the coasts that don't have lots of outer reefs but it could still be workable.

The Cable Stations comments are correct, it works well however it is just a little too deep to break nearly often enough.

The key problem in Perth (limited swell aside), is there minimal coastal variation between Swanbourne and Trigg Point, a very long stretch of sand, only broken up by a couple of small groynes at City Beach & Floreat. This creates long closeouts which need something to break them up . So to those who say an artificial reef would create crowds, do you want crowded straighthanders or a crowd on something you have the chance to actually surf.

The other interesting point that affects these discussions is the lack of tides. Southern WA is one of the few places to only have one tide a day, so rarely can you wait for the tide to improve it like you can everywhere else.

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uncle_leroy commented Saturday, 21 Oct 2017 at 10:52am

This report is done up by a company based in SouthPort qld, for a beach in Perth, mmmm local knowledge. Who's funding the report? government grant scheme?

I can see it being a waste of time and dollars, there are much cheaper alternatives that can be removable if any adverse erosion impacts are observed.
You would need to re-wind the clock back to the 1950's/60's to see that the trigg to floreat was actually a series of patchy offshore low lying reef systems (historical fishing publications) that sat probably about where the current water line to surf zone is now. Trigg islands wasn't called an island for no reason. Gradually over time with carparks, development and dune vegetation, the sand volume has increased to council delight. Good for development with no erosion, bad for previous inshore reefs and surfers, with a straight beach line.
What do all the great beach breaks of the world have.....offshore sand barsor reefs that split up the swell and throw out peaks or allow a corner to slide into once it hits the beach.
The best solution I can offer is sea containers, filled with rocks, holes to allow air to escape so they sink, attach a couple of oversize sand anchors and drop a series of them 100m offshore and let the sand build up or gouge out around them and see what that does. If they cause any adverse erosion issues that have the 'save the dune' types complaining or council stressing, they can simply be lifted up and removed.

bish's picture
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bish commented Saturday, 21 Oct 2017 at 11:27am

Containers filled with rocks and placed offshore, another interesting idea!

Bish

Noel's picture
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Noel commented Saturday, 21 Oct 2017 at 12:39pm

Sorry, steel boxes in ocean for a surfing reef are a terrible idea.
Rust quickly, create voids and sharp jagged bits. Later, as corrosion progresses they will break up in major storms and large sections will start to move around, and turn up anywhere later. Horrible outcomes.
Dont go there.

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uncle_leroy commented Saturday, 21 Oct 2017 at 1:23pm

You're missing the point Noel, they are not a surfing 'reef'. They are just to break up the straight swell lines or work as an offshore sand trap (where beachbreak quality waves are made), out in 10-12m of water a hundred or few hundred metres out to sea, never as a surfing reef as your referring to.
Rust quickly? plenty of steel ship wrecks still kicking around long after they were wrecked, yes they are deteriorating but also not rusting away over night.
It would be a short term solution to see if it was a feasable and produced better quality waves on the beach, if it worked, removed them and then make something more permanent, concrete modules of just drop in large granite boulders the size of cars or greater.
Do you think an artificial reef placed into the surf zone will be in the same spot it was placed in 20 years time? it won't be, storms will rip it to shreds on an open beach, even as flat as scraborough is for 95% of the time, big NW blow and it will get rolled around guaranteed

udo's picture
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udo commented Saturday, 21 Oct 2017 at 11:27am

No need to fill the containers with rocks..empty and sunk would be fine.....bit concerned about there lifespan though if you did need to remove them.

uncle_leroy's picture
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uncle_leroy commented Saturday, 21 Oct 2017 at 1:25pm

Longterm - 40 years, yeah they wouldn't be up to scratch, but treat as a project, if it worked then rip them out and put in something more permanent

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Noel commented Saturday, 21 Oct 2017 at 1:05pm

Another aspect of artificial surf reef proposals in WA is the politics of coastal engineering consultancy in WA.
Not mentioning names but the 'old school' old guard continue to advocate monstrous shore-piercing rock groynes as the only solution for coastal erosion control and I suspect they will go out of their way to undermine these ASR proposals amongst the decision makers at State Govt and Local Govt level.
The specific battle ground seems to be around the idea of using submerged off-shore structures to work with the elements and create an inshore salient to build up beach width. As per the Narrow Neck project. The WA old school wont hear of it.
I saw them in full action at a WA Coastal Conference a few years ago and they are dead against any attempt to consider new thinking. So until they retire or die off I reckon they will be opposing these projects as much as they can.

indo-dreaming's picture
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indo-dreaming commented Saturday, 21 Oct 2017 at 1:12pm

I don't think you can go past granite, granite is super dense and heavy and growth of all kinds will quickly grow on it giving it some padding and attracting fish life.

If there are concerns about entrapment points this can easily be fixed with filling with concrete or any razor sharp edges can be chiseled back, but ideally you want some holes and crevices etc for fish and marine life to hide and live in.

uncle_leroy's picture
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uncle_leroy commented Saturday, 21 Oct 2017 at 1:33pm

Need to think about the complexity of world class beach break, why do they break they way that they do? offshore bars from rivermouths or swell lines being broken up by offshore reef systems.
Need to move away from thinking of creating a wave in the existing surf zone, to creating a suitable environment offshore that will produce waves on the beach that is already there.

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stunet commented Saturday, 21 Oct 2017 at 6:22pm

Bang on, Leroy. Think about 13th Beach with it's offshore reefs and what they do, or Bendalong, or Congo, there are more but the premise is the same: the outside reef preconditions the wave, makes the swell line wedge or wrap, so it breaks as a teepee inside.

The proposed reef at Scarbs has a conical focussing toe that extends twice as far out as what the length of the ride is. It's not exactly the same as the beaches listed above but the thinking is along similar lines. It's arguably the most important part of the reef shape.

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Blowin commented Saturday, 21 Oct 2017 at 7:01pm

All my favourite beachies have offshore bombies.

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GreenCT commented Saturday, 21 Oct 2017 at 6:17pm

Indo D - why granite of anything heavy. Unless it is sitting on reef it will get undermined and move.

Why not a light weight solution of a large blanket which is pinned by driving pins into the underlying reef. Then on the top side of the blanket are ribbons or fonds that mimic the seagrasses that catch and hold sand.

So a sand trap scuptured to make the bank and then once filled sand can move on.

You could have 10 of these for the price of anything like a granite reef. one every two hundred metres thats 20 waves with a left and right along that stretch

The key is capturing and holding sand I think without an old school groyne which just makes a problem north from lateral drift in the summer

indo-dreaming's picture
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indo-dreaming commented Sunday, 22 Oct 2017 at 8:40am

It's an interesting idea that could have merit, but could also have its own problems and still relies on sand banks to form.

I agree it's pointless trying to create a hard rock reef unless you have a good base to work with, don't know about the beach talked about but many beaches do have solid rock a few metres down.

But if you can get it right it's there 24/7 and not going anywhere.

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radiationrules commented Saturday, 21 Oct 2017 at 6:21pm

"quarried rock will produce a very rough reef surface with dimensionally uncontrolled spaces between the rocks likely to contain numerous possible entrapment points" - getting super excited now!!

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sypkan commented Sunday, 22 Oct 2017 at 1:42am

I've often thought why not sink an old ship just off shore to either create a break or to at least break up the swell for a beachie?

Apparently this is an economical means to dispose of ships and create dive locations.

They can do this sort of thing for divers, so, on a per capita basis, surely there's more surfers than divers that could benefit from such a project. Or is it a case of divers are held in much higher regard than scummy surfers?

A well placed ship hull with waves breaking along it sounds great, and it could also be a dive/fishing venue on flat days.

I've also thought about using barrels, bottles, or containers of any kind etc. and fixing them to a dodgy reef/beach floor to create low budget DIY improvements.

Surely a hollow strong structure that fills with water is almost the same as a fully solid structure?

Much easier to drag empty 40 litre containers out to sea in your tinny bit by bit than 40kg chunks of granite.

indo-dreaming's picture
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indo-dreaming commented Sunday, 22 Oct 2017 at 8:45am

I think the container thing would only work if the containers themselves are very heavy, if just plastic etc and filled with water I'm sure they would move even if quite large.

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sypkan commented Sunday, 22 Oct 2017 at 10:14am

Yeh you'd have to pin them down somehow. Even roughly tied together with a bit of movement would be enough though I reckon.

Yeh I agree the bommie thing is a bit of a longshot for a b grade beach break outcome (hopefully)

I'm more picturing an upturned cargo ship placed just below the water line, with a peak coming up from the bow, then peeling left and right down the line of the ship and barreling for about 200 metres or so.

I might be overcooking it a bit.

indo-dreaming's picture
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indo-dreaming commented Sunday, 22 Oct 2017 at 8:52am

The outer reef bombie thing to break up swell always comes up here with these artificial reef topics, and i agree it has merit and many good beaches have this set up.

But since its been brought up here (for years) I've noticed even these types of offshore reef structure in nature actually rarely create good waves.

IMO It would still be very hit and miss.

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stunet commented Sunday, 22 Oct 2017 at 6:27pm

Curious at the locations that have the set up but not the quality?

It's an imperfect science, but then randomness is at the heart of the matter, that's what you want as opposed to a uniform closeout, and there are so many set ups on the east coast that have the offshore bommie or sand deposit (like D'Bah or Tuncurry) that it's an obvious starting point.

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indo-dreaming commented Monday, 23 Oct 2017 at 7:36pm

If all the aspects of the set up are there then it possibly works.

What i mean is just like an artificial reef, i don't think it will work if you just plonk a reef offshore and expect it to break up the swell into peaks.

I think its like an artificial reef where you need all the other dots there to start with and then the artificial reef is what joins the dots.

I think the shape of the sea floor and water depths etc are just as important out behind the reef that breaks the swell up and then the sea floor shape and water depths etc between the reef and beach.

Just locally where i live on my local beach Woolamai down at Ocean reach just to the right of the steps offshore about 100 metres behind the outside bank is a reef that waves suck up on when its bigger, you would expect this reef to increase the quality and focus the swell and it looks like it wants too, but it never really does what you would think.

Then further along down at surf beach there is an offshore reef that breaks on low tides in big swells similar kind of deal.

Then further along at Smiths beach there is some big rock reef a few metres hundred metres offshore that i now look at and think waves peak up and break on it but it doesn't actually improve the waves when they hit the beach, make the more peaky or focus it into a peak.

Few other back beaches I've walked to and observed similar set ups.

velocityjohnno's picture
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velocityjohnno commented Tuesday, 24 Oct 2017 at 10:46am

If you've got 10 minutes, take a look at Lanno on the satellite view of google maps, note the reef chains and the bombie just outside the back beach. Back beach is not epic, but it's shape is usually much nicer than the Scarb stretch.
Then head north of the town and check out the mixture of reef/beachy setups - these are usually better shaped still.
I'd contend in a WA setting that you also need to banish development from the foredune if you want banks, and absolutely banish groynes or marinas south from anywhere near where you want to keep your foredunes.

Clam's picture
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Clam commented Tuesday, 24 Oct 2017 at 9:32am

"The Scarborough proposal starts with a conical ‘wave focussing toe’ designed to refract the incoming waves toward the centre of the reef.
From there the reef has a left-hand arm running at 40° designed for intermediate-level surfers, and a right-hand arm running at 45° for advanced surfers.
Each arm is 90 metres long and will offer rides from 40 metres to 120 metres depending on conditions.

The ability to work in a range of conditions, particularly low energy conditions, is paramount, though the report states that during Perth’s infrequent big swells the reef “is expected to produce excellent surfing conditions of very high quality.” unquote.
-----------------------------------------------------
This 40° & 45° left and right hand wave angle is bullshit !
Who's idea is this ?

What angle of swell are they basing it coming from ?
What is the predominant angle of swell supposed to be from ?
I hope they realize that wnw swells are common according to the WA Department of Transport buoys ie Cottesloe, Rottnest & mandurah .
Local surfers know this odd fact but surf forecasting websites dont suggest this, they usually say SW swell , so im not sure everyone knows that.

https://www.transport.wa.gov.au/imarine/cottesloe-tide-and-wave.asp
https://www.transport.wa.gov.au/imarine/tide-and-wave-data-current.asp

stunet's picture
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stunet commented Sunday, 22 Oct 2017 at 6:29pm

Think the average swell direction was just south of west? (It's in the Feasibilty Study). If it differs from buoy averages it may be because they've filtered out wind chop.

Clam's picture
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Clam commented Tuesday, 24 Oct 2017 at 9:35am

Stunet: "Think the average swell direction was just south of west? (It's in the Feasibilty Study)"

Hi stunet where is that info available please ?

If they base this angle of attack on swells sth of west then the left will improve when an actual wnw swell comes in .
Imagine pointing the reef toward rottnest island huh !

stunet's picture
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stunet commented Monday, 23 Oct 2017 at 12:18pm

See the link in the article Clam.

_Ryan's picture
_Ryan's picture
_Ryan commented Sunday, 22 Oct 2017 at 4:41pm

Location wise we should be putting them in places that dont already get good banks. The location you have chosen in scabs already gets good banks part of the year.
Cant you guys modify the reefs near north beach and yelo? There is plenty of swell around there its just the reef is the wrong shape. Couple of mods and that area would pump.

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Legrope commented Monday, 23 Oct 2017 at 4:43am

Yeah Mate, I fully agree. That's what I said at the start. So many reefs just north of Trigg that get consistent swell but just need a bit of enhancement and they'd be surfable. Some massive barnacles on those reefs so it would keep some of the kooks away. At least 5 set ups that could work easily.

udo's picture
udo's picture
udo commented Sunday, 22 Oct 2017 at 6:10pm

Ian Cairns Yanchep Sun City 1974 - Artificial Reefs
Wonder what reef designs Kanga had all those years ago ?

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happyasS commented Sunday, 22 Oct 2017 at 6:28pm

pretty sure the last time I surfed scabs I was completly bent. that was a long looong time ago. that stretch of beach needs all the help it can get.....sooo straight.

would love to see it work out. yah

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Noel commented Monday, 23 Oct 2017 at 11:59am

Lots of comments here about the proposed location.
Page 12 of the report, the report being what this discussion is all about after all, provides a colour-coded bathymetry image which makes it clear that the chosen location, as shown on page 18, is just on the northern window of the deepest approaches to the beach. So even though its not centrally optimised according to the bathymetry data it is still in the zone that gets maximum swell. From the small number of times I've surfed that area in Winter its clear to me its in the maximum power zone.
All the locations to the north of 'focal zone 1' show light green outer reefs as a broad barrier then dropping back into deeper water. This is the best way to knock the power out of swell.

If we all get excited about articles on Swellnet and Surfline that reverse engineer the bathymetry of primo surf breaks around the world then we should respect what these people are trying to achieve. In this case I reckon their science is validated by my 'seat of the pants' experiences on that beach, so I can dig it.

And, having a bit of insight into how the gods of funding must be appeased, I can also get why the centre stage location of redeveloped Scarborough is being proposed.

Whoee's picture
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Whoee commented Tuesday, 24 Oct 2017 at 12:52pm

Looking at the bathymetry, you're correct. Problem is, it is already focusing onto a spot that produces a reliable bank every year. I think this forum has anecdotally proven this. I believe the researchers wouldn't have picked up on this being a reliable spot because they don't have the long-term local knowledge. So the question i think you need to answer Noel is, why build a reef over the top of an existing break? With such limited options in Perth, we need as many breaks as possible. Move it 200m north or south and there would be no issues.

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Noel commented Tuesday, 24 Oct 2017 at 1:27pm

I think you are making an assumption to say the researchers dont have the local knowledge. You would be surprised how many people with surfing backgrounds get involved in engineering careers in WA. So I would expect that the team behind this study includes at least several surfing or windsurfing or kiting enthusiasts. For example, I know of one guy who did his Mechanical Engineering thesis on computer modelling of surfing reef designs. So who knows how many surfing enthusiasts gravitate towards Civil and Coastal Engineering.

Its not my question to answer, but I will put up a couple of considerations as to why they might have chose that section of the maximum swell window with regards to bathymetry.

There might be a compromise as they want to stay in the max swell bathymetry but remain as far from the patrolled swimming beach and windsurfing & kiting zones as possible.
This might be an attempt to provide waves all year round in the max swell bathymetry zone instead of there only being surfable waves at the mercy of the sandbank gods for a relatively brief part of the year.
And there have been enough artificial surf reef failures around the world, and they just want to use the science to try and ensure the highest chance of building a reef that breaks as often as possible, compared to say Cable Stations to use a nearby example.
As I stated previously, if this goes to public comment it will be highly contentious and I have no doubt that a lot of people, including surfers, will loudly shout don't build anything anywhere. and others will say dont build it in option 1, and before you know it the pollies will get weak kneed and it will end up as an aquatic version of the NBN.
Who knows, option 1 might be an ambit claim and they really want to build it further north. Who knows?
.

Whoee's picture
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Whoee commented Tuesday, 24 Oct 2017 at 3:16pm

OK, so my wording could have been different, but i think you've missed the point which is that it's pretty common knowledge among most regular scarborough surfers that there is a reliable bank in the area they have recommended. It is so common, that everyone refers to it as the Manning Street bank or the Peter's (by the Sea) bank. This suggests to me that there's some major flaws in this research:
1. It has not identified that there is an existing well known break in the area
2. They've not highlighted the fact they want to build over the top of a know surf spot

So the problem is that when this is handed to non-surfers, they're not going to know this information. People without knowledge of surfing are going to rely on this document to make decisions that affect us as surfers, and the document is missing a significant piece of info.

So Noel, if the report did say there was an existing break and they wanted to build over it, would you still be supporting this location, even though the bathymetry shows it as the best location?
For me, it's a no, because i'd prefer to have 2 breaks in the area (the mediocre Manning St Bank and better artificial break) rather than just 1 better artificial.

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Noel commented Tuesday, 24 Oct 2017 at 4:04pm

that being the case i agree with trying to steer it towards another site. I dont live there so I dont have any say in it, for what thats worth. Its your gig.

But...... be very careful about how that message is communicated back to the decision makers because these projects are few and far between because some pollies will latch onto any reason to spend that money elsewhere. And the media will be happy to fan the flames.

Talk to Surfing WA, dont leave it to chance.

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Legrope commented Monday, 23 Oct 2017 at 1:04pm

I've surfed that stretch on and off for the last 30 years and have had a few great surfs along that stretch albeit after a decent storm which broke up the straight hand banks. People spread along the whole stretch. If a structure is installed then it will concentrate everyone to that one area. More than likely bugger up the banks up to Trigg giving one surf spot for everyone as opposed to as it is now. Imaging 300+ people on the one peak. I suppose it will be like moving everyone from Trigg point, down the beach and adding them to the Scarborough pack. Why use the prime central swell zone for an experimental reef which may or may not work. The whole coast, 5kms north and south receives the similar amount of swell. If it doesn't work, it will piss off every surfer in Perth making that stretch less surfable than it already is. If it's going to be on sand, why not experiment south of Scarborough first or enhance the almost surfable reefs north of Trigg which still get similar swell?

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Noel commented Monday, 23 Oct 2017 at 1:43pm

no doubt the Consultant dudes are already monitoring this discussion, and no doubt if the project moves ahead you will be able to make comment during the public consultation phase.

I expect it will be quite contentious.

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waverat commented Monday, 23 Oct 2017 at 1:07pm

What about pouring truck loads of rock in between the point in front of Harbord Diggers and filling in the space through to South Curly pool? Fill it up slowly and see what happens every time a straight south swell hits the northern beaches and everywhere is closing out. Wait for a swell, record the outcome and pour more rock in to the bits that don't work. It just looks like it wants to work through there.

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waverat commented Monday, 23 Oct 2017 at 1:21pm

https://earth.google.com/web/@-33.77829055,151.29600156,0.40464509a,2118.51824589d,35y,0h,0t,0r

Halfscousehalfcockneyfullaussie's picture
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Halfscousehalfc... commented Monday, 23 Oct 2017 at 3:09pm

Now I know this is a totally different location. But Newcastle harbour is a decent man made artificial reef, albeit an accident. Maybe that's another location to take a look at to see why it Worked.

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Clam commented Monday, 23 Oct 2017 at 11:14pm

"From analysing the annual wave climate at the toe of the reef the wave direction was found to be very close to due west (Figure 3-6). The reef was aligned to the mean swell direction
(272°) derived over the annual wave climate."

The article linked is good .
thanks stunet !

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Clam commented Tuesday, 24 Oct 2017 at 9:38am

"the wave direction was found to be very close to due west (Figure 3-6).
The reef was aligned to the mean swell direction (272°)
derived over the annual wave climate."

272 degrees is just north of west stunet !

stunet's picture
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stunet commented Tuesday, 24 Oct 2017 at 9:44am

Hmmm...got me there. Yep, just north of due west.

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velocityjohnno commented Tuesday, 24 Oct 2017 at 10:42am

Like some have said, how about placing it north of Trigg Pt, in an area that's mostly rocky and the reefs are *almost* breaking in what we'd recognise as surfable waves? Use current structures underneath, infill etc. That area gets the same swell the point does.

Imagine the parking into North Beach if they succeed there...

frog's picture
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frog commented Tuesday, 24 Oct 2017 at 1:49pm

Some technical points:

Enhancement
Enhancing existing rock structures / reef has huge benefits as it can remove the subsidence issue from scouring a reef laid on sand will have - eventually they will sink into the sand if placed on a bed of sand unless they are massive big rocks laid thickly (e.g Kirra Groyne). If the sinking factor is removed and nature provides the foundations it saves a lot of money.

Refraction
Outside reefs that refract swell into peaks have to be substantial in length and close to the surface to work - multiples of wave length will bend swell. Short bombies will not - waves just passes right over and reform with barely a hint of refraction. The outside reef has to virtually break like a proper reef with length in moderate swell to really break up the swell into peaks (e.g 13th Beach). Even then, if there is not a hint of a bank inshore, they will be a peak that closes out super quickly. The outside sand slug / reef concept therefore needs a huge volume of rock / sand to create the scale of bathymetry needed to create a good surf spot (length x width x height adds up very quickly in deeper water).

Sand build up
Don't rely on sand build up unless you have a lot of longshore drift. Lots of rock structure have zero sand build up.

Design must assume the reef has to do most of the work and it needs to start well out from the break to build up the peak. So a lot of rock and careful design is needed. But once done right it is there forever - no need for maintenance, lawn mowing, electricity, weeding etc.

Frogg

Whoee's picture
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Whoee commented Tuesday, 24 Oct 2017 at 2:27pm

Anyone want to have a go at explaining why stabilising dunes and grooming beaches in Perth has lead to a decrease in wave quality, because i'm calling that these 2 things don't affect it at all. Here's my opinion why:
GROOMING - What everyone is calling sand grooming is just a sieve picking up rubbish. There's no movement of sand. Sand is passed through the sieve and dropped back exactly where it came from. How does this process impact the quality of surf when there's actually no movement of sand?
DUNE RESTORATION/STABILISATION - There's no doubt this was done to stop sand being blown across infrastructure and restore the dunes to how they were. So how does this affect wave shape? How does allowing sand to be blown inland create better waves? Or is the claim that we need to lose sand from our beaches? Or is the claim that the dunes were established in the wrong location? If so, wouldn't mother nature have reshaped the environment back to how it was meant to be? For example, when a dozer did reshape Scab's, it returned back to how it always was pretty quickly. I've not seen any major loss of dunes along the Swanborne to Trigg stretch that would indicate they're not following the natural beach line. In the rare event that water laps at the foot of the dunes, the beach is naturally replaced pretty quickly. So i'm not seeing how dune regeneration is affecting wave shape or the shape of the coastline.

The things i've noticed about our stretch of coast and the movement of sand are:
1. The waves seem to break in the same location every year (obviously this is a general comment and subject to swell size). It is the beach line that moves in during winter and expands out during summer.
2. The expansion of the beach happens from South to North. ie. There's winter breaks at places like Hale road, but as summer and the sea breezes occur, these breaks will disappear from South to North, to the extent that the waves break directly onto the shoreline.
3. It's the sea breeze in summer and cold fronts in winter that shape our sand banks.
4. City and Floreat groynes have an effect. It's clear they hold sand during summer and winter. They're the only permanent feature that affects sand flow. Would their removal cause erosion to the extent that it would affect the entire Swanny to Trigg stretch?
5. Removal of the reef out the front of scarborough would surely have had an impact.

Keen to hear everyone's theories.

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stunet commented Tuesday, 24 Oct 2017 at 3:07pm

@Whoee,

A partial reply...

It's become fairly well known that introduced Marram grass, which does a better job of binding sand dunes than the native Spinifex, also alters beaches in previously unexpected ways. Marram locks more sand in the dunes, removing it from the shoreline interface where it stays in flux and helps with bank formation, and it also creates steeper beach profiles which aren't conducive to good waves.

I'm not familiar with Perth beaches enough to comment on profiles but I know Marram is planted there.

https://www.swellnet.com/news/swellnet-analysis/2015/10/07/damned-marram-not-all-grass-good-your-surfing

Also, sand grooming, at least on the east coast, will flatten the scallops along the tide line and daily repetition impedes the formation of strong rips (a rip will push back out where the scallops dip inward).

It means it's safer for swimming, but not a good result for surfers as strong rips are good for banks.

Noel's picture
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Noel commented Tuesday, 24 Oct 2017 at 3:44pm

Marram is despised by the coastal ecology purists. Its from Seth Efrica and it spreads very successfully without human help.
It actually thrives on fresh sand-flow. So it propagates on the down-wind micro-dune faces that are constantly being renourished so it grows and builds the dune continuously all year round.
Our local beaches had a major re-planting program in 2006, incredibly successful establishment and dune growth towards the ocean and the last few winters the beach hasn't retreated anywhere near where it consistently used to get to.

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quokka commented Tuesday, 24 Oct 2017 at 4:11pm

I can comment Stu, they're uniformly steep at the water edge and pretty straight.
Ban the grooming and remove the dune vegetation would be a good start. The FB vid from Beach Care Illawarra that Craig posted back in Jun last year is interesting https://www.facebook.com/simon.avery.79/videos/985974811518548/?pnref=story.

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quokka commented Tuesday, 24 Oct 2017 at 3:35pm

Whoee I'm going on personal anectodal evidence alone and there are two things that I have seen change on the Perth coastline in the 40+ years I've lived here (born and bred and yes not giving away my age completely!):
1. The North Mole and Rouse Head groynes - I do believe these have had a major impact on sand flow from South to North, I don't believe City Beach and Floreat groynes have had any impact, even these don't get the waves they used to;
2. Re-vegetation of dunes or development of dunes.

Re point 2, I believe it's the natural flow of sand into the ocean from the dunes via east winds that used to assist with replenishing sand but this is no longer possible because they have been stabilised. If you've been to any WA beachie on a howling easterly you know it's like being in front of a sand blaster with the sand coming off the dunes and beach. The easterlies no longer have this affect in Perth because the dunes "hide" the beach from their action and vegetation protects the dunes. You've got to give it to the green army their intention to stop dune erosion has worked.

I also believe the grooming doesn't help as it does create a very steep beach, not sure the effect of this but it never used to happen so it is something that has changed in the past years.

I think the Hale Rd stretch and south of City beach don't get any waves as the water seems much deeper closer to shore and the coast is extremely straight....even Scabs and Trigg have slight variations in coast alignment which I assume contributes to causing banks. just chucking ideas out there as what I believe to the be most probable causes.
If you disagree, what do you think are the reasons for the obvious decline in Perth surf quality?

P.S. You aren't defending the dune planters because you've had the gardening gloves on? :)

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mickj commented Tuesday, 24 Oct 2017 at 4:55pm

Loving how much interest is being expressed in the much maligned - with good reason I may add - topic of surfing in Perth. Yes I am a local too, so can empathise with many of the comments above.

Funnily enough I've spent the last year or so talking with the City of Stirling about many of these same issues, and have pasted three emails I've received back from them on the topic below. They're quite open about many of these issues and I recommend anyone wanting to dive into it further contact them directly.

Two related points before reading on:

1. The first email refers to a paper that I had verbally confirmed from the City in 2015/6 was scheduled for public release in 2017. It's not out yet (maybe 2018?) but appears to still be on track for release at some point.
2. Important also to realise that this whole topic of an artificial reef at Scarborough is conceptual only at this stage, and I think it will remain that case - probably forever - due to a lack of funding. See comment here that neither the City of Stirling nor the Metro Redevelopment Authority (who are funding the current overhaul of the beachfront at Scarborough) have any intention of funding it (http://www.perthnow.com.au/news/western-australia/169-million-artificial...). And given the parlous state of public finances in WA at present, can't see that changing any time soon. As for the private sector paying for it, zero chance - impossible to monetise a return and far worthier recipients for any philanthropic intervention I would think.

The sand movement & replenishment / Marram Grass / beach grading issue along Trigg to Scarborough however is a real one and is absolutely of public interest. It's a matter of fact that those dunes have been artificially stabilised over the years and are currently holding much more sand than is historically "normal", which the City has recognised. Clearly this is sand that's not available for bank shaping in the littoral zone, nor available to replenish beaches further north - as was naturally the case pre Marram grass . I would also add the Hillarys Marina further north again traps sand movement the other way (from the north in the winter time) and further starves the Trigg to Hillarys stretch of coast of sand.

I agree with the general mood above too that the beaches and reef structures along here are dying to be modified surf wise but it will never happen - approvals alone would be a nightmare, let alone figuring out once again who pays for it.

Happy to share my contacts at the City of Stirling (via Stu) with anyone that is interested.

Cheers,

Mick Jardine

Email #1
You may probably be referring to the three-year study that was completed last year by a consultant group that looked into beach profiling and sediment transport along the entire 6.5 km coastline of the City of Stirling. This was submitted to Council for endorsement earlier this year. It is being edited for insertion on our website. Council has approved further work in terms of geotechnical surveys of the calcified dune areas north of Trigg Point to supplement the beach profiling and sediment transport study.

Email #2
"Introduced Grass Species affecting Coastal Dune Dynamics – South Trigg Beach
 
Thank you for your recent email in reference to the above. I have read the paper that you provided the link to but am not aware that the City had any involvement in disseminating this paper to a wider audience.
 
The work that the City is currently undertaking in South Trigg Beach involves eradicating the introduced Marram Grass and Sea Wheat and replacing these with coastal native dune species such as Spinnifex hirsuitus and Spinnifex longifolia.
 
Both the introduced grasses and Spinnifex species are valuable in encouraging dune building but the introduced grasses tend to hold on to the sand resulting in abnormally high frontal dunes whilst the Spinnifex species have the ability to allow some seasonal sand depletion thereby maintaining the dunes at sustainable heights.
 
It is anticipated that this will, in the long term, create a balanced situation as far as dune height is concerned. It is the City preference to continue the process currently followed rather than having to mechanically grade and lower the dunes in South Trigg Beach."

Email #3
Apologies, I did not realise that you were referring to coastal sand nourishment. Well, from previous and recent studies plus observations over the last 40 or more years, we know that Scarborough Beach is an accreting beach to the extent that the City has to annually (in October) grade away sand from the beach as well as uncover buried fences along the toe of frontal dunes. The sandy beaches just north of Scarborough Beach (viz. South Trigg Beach and Trigg Beach) are less accreting and in fact regress to some extent in winter.
 
On the other hand, the bay beaches to the north of Trigg Point show the reverse pattern and tend to loose a lot of sand northwards towards Marmion and Hillarys Beaches each winter.  
 
The surplus sand that is graded away from Scarborough Beach is not removed but pushed back into the ocean at per-determined points in between sand bars off the beach. We know from our littoral drift studies that this sand actually gets carried northwards to be deposited in the bay beaches north of Trigg Point each summer. This used to occur naturally at a time in the past when Scarborough Beach was a lot wider and before the artificial dunes were built off the Scarborough esplanade.
 
From our experience, direct sand nourishment will not work unless it is undertaken at the right time of the year and at a location that has the propensity to accrete sand. We know this from the disappointing results some years ago of sand nourishment carried out in Watermans Bay from surplus sand ex Scarborough Beach.
 
In reference to your query about whether sand nourishment could be undertaken in South Trigg Beach – well, I admit that this location is a bit of an unknown because it is on the cusp of the two types of beaches that are either sand accreting or sand depleting. The work that we are currently doing in the frontal dunes of South Trigg Beach in replacing the invasive grasses with local native coastal plants will hopefully restore some balance in the way that dunes act as a repository for the seasonal accumulation and release of sand back to the sand cycle.

quokka's picture
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quokka commented Tuesday, 24 Oct 2017 at 6:59pm

Excellent info Mick. I fear that simply removing Marram from Sth Trigg dunes won't have a huge effect. Also unfortunately the re-development of Scabs is not helping as this has/will permanently narrow the beach plus they won't want sand blowing back into their newly manicured parklands etc. I'd be interested to know why Scabs is an accreting beach and Trigg a depleting beach?
I'd also be interested to know who to contact at CoS to discuss all of this?

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mickj commented Thursday, 26 Oct 2017 at 4:24pm

No probs mate, you can get me on [email protected] and I'll send you the details there. Cheers.

indo-dreaming's picture
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indo-dreaming commented Tuesday, 24 Oct 2017 at 6:20pm

Seems quite a few people saying why are they putting it where the best banks already are.

It's quite obvious they are putting it where it is because, that location has the best chance of creating good waves.

This is the kind of approach that needs to be taken you want to give it the best chance of success as possible, I'm sure if it is a success then they may look at improving other areas of the beach.

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halleys-comet commented Tuesday, 24 Oct 2017 at 8:43pm

Hi ID,
I get your point, but conversely if they build an AR in a place with existing surf they can stuff the surf up. The ASR (now defunct) AR at Mount Maunganui, NZ., was not a success and has since been removed.

daComet

indo-dreaming's picture
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indo-dreaming commented Tuesday, 24 Oct 2017 at 9:46pm

What do they say "nothing ventured nothing gained"

Plus if it really does stuff things up they can remove things.

Also you would imagine they could take a stage by stage approach.

simba's picture
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simba commented Tuesday, 24 Oct 2017 at 7:56pm

simba

happyasS's picture
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happyasS commented Tuesday, 24 Oct 2017 at 9:22pm

17 million to dump rock into the water. at least a wavepool would work all year round, something even the best engineered artificial reef will hardly do during Perths pancake summers.

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steveb commented Thursday, 26 Oct 2017 at 6:14am

Indo dreaming-re "If there are concerns about entrapment points this can easily be fixed with filling with concrete or any razor sharp edges can be chiseled back"

The way to create surf reefs is to pre-fab the structure, float it out and sink it onto engineered footings- , stable, safe, perfect bottom shape=perfect wave shape......done!
(and fully removable if you want)

Clam's picture
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Clam commented Thursday, 26 Oct 2017 at 11:34am

Who's paying for this anyway ?
A 2 million dollar version back in june....

http://www.communitynews.com.au/western-suburbs-weekly/news/scarborough-...

"The Scarborough Beach Association (SBA) recently revealed its Action Plan to revive the foreshore precinct with short-, medium- and long-term goals, which include a $2 million artificial reef."

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rooftop commented Thursday, 26 Oct 2017 at 2:07pm

For what it's worth, I'm all for it moving south to the underutilised Floreat-to-South Scarbs stretch, as it currently gets swell but no banks, as others have already pointed out. It would also lessen the risk of conflict and collision between surfers and clueless tourists. Plus, there's parking.

I suspect, with all the other development activity going on around there right now, that there is a commercial incentive to drop it smack dab in the middle of the beach in the hope of drawing more crowds and therefore more business to the area.

But surely, with a couple of hundred frothing surfers crawling all over that thing on an early spring swell with the water full of surf schools, backpackers and boogie boards, it ain't going to be pretty.

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SurfinDan commented Thursday, 26 Oct 2017 at 2:32pm

Has anyone ever thought about using interlocking (think jigsaw) super heavy duty plastic modules that could be filled with sand and do the job of the rocks ?
Reckon this could be a lot cheaper than using rocks as the report says the rocks cost about $7million including transport .

Clam's picture
Clam's picture
Clam commented Saturday, 28 Oct 2017 at 11:30pm

Bad idea to put plastic in the ocean i think.
The swell magnet , dome/ toe should be big rocks, nice and deep to refract the swell in .
Thats the best feature of the design .

truebluebasher's picture
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truebluebasher commented Friday, 27 Oct 2017 at 6:29pm

This iconic Manning Street break seems to share surrounding wind & beach conditions.
Running a basher'z eye over... reveals series of aquifers revving up the A frame.
Unless ASR is designed around essential aquifers then it's an act of bastardry.
Ask what nutter would cement the very power source of Manning Street A Frame.

Smothering the aquifers deadens the head and pushes more flow wide, flooding the soon dying face. Making for the lamest wave in town.
We basherz court aquifers as dance partners...here's a free tip.
Don't throw your baby out with the bathwater.

Most bodybasherz hit inclined soft sandy beaches for more rapid power backwash waves. Back of a fast moving ramped high tide delivers the best reverse aerodynamics.
No different to this gem of a wave...

Gold Coast was all mined in 40's - 50's but during 60's-70's had entry furrows shouldered by sandfinger groynes, this was lazily shaped by dopey crews tripping over A Frames.
Ironically these sand groynes slowed down the swell protecting the beach.

Simple test!
If just one sand groyne survived the mightiest cyclone.
Then surely that's the strongest arm of the beach.
Naturally one would bank on that structure as being a beacon of hope.
Truth is any/all councils would have it bulldozed within the week.
Thus revisiting the erosion cycle over and over.

Graded esplanades need footpaths need parallel dune plantings of measured fence lines. Joggers needed clean string-lined beaches with bulldozers keeping the groomers in line.
Racing track is then widened by the dredged creeks now running wild... gouging out beach gutters sandwiched in by Rainbow Dredge sand spit.
Now not one wave breaks through to shore... not even on low tide.

Age old natural whitewater ecosystem destroyed in one winter. What for our sea harvest?
Gargantuan gutter now feeds on tourists chancing the sandbank.
Councils will support any plan to take waves away from people. Out to sea if they could.

quokka's picture
quokka's picture
quokka commented Friday, 27 Oct 2017 at 7:22pm

Arvo barbie was it TBB?

truebluebasher's picture
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truebluebasher commented Friday, 27 Oct 2017 at 9:58pm

Back from the barbie...
Gold Coast ground water aquifers are contaminated more often resulting in beach closures.
The recent 'Cooly' contamination seems to be a long term shutting down of the WSR.
I guess it matters little if ASR or PFAS locks down the town.

TravJW's picture
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TravJW commented Saturday, 24 Feb 2018 at 1:16am

Any news on the artificial reef since this study?