I like the idea of half a dozen more groynes between Floreat and Trigg Point, with a ESE/WNW orientation. The only metro beaches that hold a bank for any stretch of time have some sort of structure. In my opinion, the groyne with the most potential is Sandtracks. If only that place got swell. Last winter the bank was set up so even tiny windslop was breaking 100m out on a few occasions. The good thing with groynes is they're easier to sell to the public, since City and Cott are so popular in summer with their shelter from the prevailing sea breeze.

It's always a last resort. But imagine a similar length groyne further up the coast - imagine if there were one or several 1-200m groyne(s) that held a SW cold front and gave us some structure for the swells afterwards. Ah, it'll never happen. But it'd be good if it did.

You could easily fit two or four between nude beach and City. Half a dozen between Floreat Drain and Trigg Point. I think they were all along the beach at the New York pro, weren't they? I'm sure they're used elsewhere too. I'll bet there are studies about their effects on the coastline - much more than artificial reefs. If they worked like City/Floreat I can't see how they'd be a bad thing.

Sparki that's all they were, a couple of good fronts, it used to be the norm. It wasn't unusual to get 6 or 8 or 10 big NW blows from May through August. My fingers are well and truly crossed that last year was the start of another weather cycle of proper NW fronts. If it starts happening again you won't have to worry about sand movement, it'll happen.

It's also gonna hammer a hell of a lot of coastal infrastructure that has been put in place in the last 20 or so years. I reckon the last cycle started with Alby in '78, check this;
http://floreatslsc.com/index2.php?option=com_content&task=view&id=13&pop=1&page=2

After the storm Flozzas was huge and breaking a couple of hundred meters out to sea, just fkn massive. The surf club ended up half in the drink and had to be demolished, you still get chunks of concrete showing up along that stretch after a proper front. The last really good front prior to last year that I recall was in May 1994, hell storm. And sick waves after it.

Hunt down a book by Ross Cusack called Hooked for Life, he wrote the fishing column in the West and Daily News from the 60's through 80's(?) Amazing stories of fishing thick cord handlines for big Mulloway off the reef at Contacio straight into 6m of water. Plus lots of other stuff like the shoreline around Hale Rd being 150m further east.

Maybe it's climate change, hopefully it's just cycles. But make no mistake extended thumping NW swells are the key to good surf in Perth.

I'm surprised you made no mention of the Contacio Reef, I've not seen hide nor hair of it since the early '90's and even then it was just the odd rock poking it's head out after a horror storm. Not that I've surfed the area that much in the last 15yrs.The thought of standing on a reef edge along that stretch fishing into 6m of water just fries my mind.

The Hale Rd stuff comes from interviews with real old timers that Cuey did in the early '70's, so you're probably talking '40's or earlier. And it's not that the ocean was that high, it's that the dunes were not where they are now. It all just illustrates how fluid our coastline is.

As a grom I spent most every weekend of my life at the family beach house at Moore River and distinctly remember heading south along the beach with my Dad in the beach buggy to fish (not me, I was too young) a reef that used to drop off into 5 or 6m of water.

It's not there anymore, it's buried and that's only in the last 30 odd years.

Sparki Contacio is between the north end of Scarborough and the southern Trigg carpark out the front of the Contacio units on the west side of West Coast Hwy. Somewhere under all that sand is a reef system that the old boys used to fish off into 20ft of water.

Geez, they must be OLD boys, as I have never heard of or seen the reef off Contacio's in over 30yrs of surfing along that stretch - so that's back to 1980...

...Only ever seen that 2m x 2m table-top rock at the south end of Third Car Park when the sand shifts in summer...

I was going to say... I know Contacio, but I couldn't imagine there being a reef there - let alone a 6m drop off. I'm not doubting your memory, but I just find it all a bit hard to imagine especially considering the relative recency of it all.

I find it hard to believe too Legion, it's nuts.

Almost as hard to believe as a keen surfer going to the Maldives for their honeymoon, staying walking distance from Pasta Point and letting their bride tell them it's not alright to bring a board. Now that's hard to believe! And maybe just a wee bit soft too

Sparki, not my memories and I find it hard to imagine too. As above it was from that book of Cuey's and not really that recent either probably from the '40's or earlier. I had a bit of a dig around for it earlier but I think it's already been packed for the move.
When it turns up I'll scan it and post the pic, makes really interesting reading.

gday guys
have enjoyed reading the froth on improving perth surf, and from my point of view you guys are on the right rack with a lot of the things you say and i may be able to shed some more on a few of the details and why the ideas may be good, but may never put in practice (in point form since i am at work! but could talk about these all day). Pulled out a quote or two to sort my thoughts:
- "a couple of good fronts, it used to be the norm"
That is spot on, have seen quite alot of review/reports of storm patterns and tracks for the past 30 years. We have just come out of a few years where the NW component of the fronts (ie how long the winds, and some wave direction, stay from the NW) has been relatively short, and we may be headign back to a more normal pattern. Surf wise, we get waaaaay more sand being ripped off the beach and gutters forming with a strong NW blow and higher water levels/surge. It is interesting with global warming claims etc, talking about whether storms are stronger/weaker/less frequent, waves bigger/smaller blah blah blah, that the evidence i have seen for WAs south west coast is that the storms are getting more intense, but the tracks of them are shifting lower (or being pushed lower) so we are not getting the full brunt...but when we do...oh boy


-"the idea of half a dozen more groynes between Floreat and Trigg Point"
The reality is that coastal managers view groynes as coastal protection structures - ie protecting what is behind them and at risk. A groyne field works by compartmentalizing the sand transport, so in a southerly pattern (wind/waves from south) the sand builds up on the southern side, but this also leads to scouring on the north side - which is why the wave forms well (bar as sand leaches around, but a gutter and erosion on the inside). Go check out Mandurah northern beaches if you want an example of how this can both work - or cause huge erosion problems if you don't have enough buffer on the northern side (ie carpark falls into water), or a balance of the directional pattern, so that a northerly pattern then sends some sand back into the northside of the groyne again.
So - no one will ever build groynes for us unless there is something to protect behind, and the local govt would also likely lose some coastal reserve on the northside if you built any decent sized groynes on the stretch from floz to trigg. Or you would need to have them designed and built the correct distance apart along the whole 4km stretch (say 20 to 30 of em!!!) to totally compartmentalise it - and no one really wants that as it would look hideous.

My take on improving that stretch is that it is transformative ie it acts like a low energy beach at time, and a high energy dissipative beach at others eg when you get banks outside and gutters. To improve it you need to establish fixed structures offshore but close enough still to change the energy dissipation to the beach. Because there is so much sand transport as i mentioned, you risk anything you build getting big scour holes and sinking, so i reckon do a geo survey - find any sections with underlying rock offshore (eg see how far out the contacios bit may really go) and then design a rubble mound underwater groyne that could then sink to the base rock and stay a realtively decent depth. 4 or 5 of these along that stretch and we might get regular shape - but without the foundation they would quickly disappear. Might even get a ridable bombie out there in a big enough swell.
Check Town of Cottesloes investigation of underlying rock levels/areas if you are interested in the sort of data they are collecting these days.

The sand transport along the stretch between swannie and trigg is actually pretty bloody big - i would guess at 150,000m3 per year net to the north due to my work, but i am probably underestimating. The thing is that the sand moves offshore and cycles around in these big cells and forms bars offshore, and it is so much harder to track and quantify out there compared to what we can see. For example - think of between hillaries and ocean reef boat harbour as a relatively natural "cell", where the breakwaters (or rocky beach platforms if the harbours hadn't been built), keep the sands from building up as a beach and therefore it stays offshore and gets moved with the currents, but the offshore reefs also act as a boundary at times, and a feed at times. Cockburn sound, and Warnbro sound have pretty cool examples of this when you look at really good bathymetry as well.

PM if you are interested in any further convo, or my background - won't go public with it but i am involved with some coastal engineering and sand movement within WA.

hoep everyone gets a afew this week! cheers

GPA said...

^^^
Thanks for posting mazdon - it was an interesting read...

On a slightly unrelated note - do you happen to know what is happening with the potential artificial surfing reef that is supposedly part of the upcoming Ocean Reef Marina development...? There's not much info on the City of Joondalup website...

cheers- GPA

another artificial reef where there is a swell shadow - great

I mean:

- (despite what SubaBoy says about Leighton) Cables artificial reef has a shadow from Rotto
- Ocean Reef has a significant shadow from outer reefs

I realise of course, that we are unlikely to get an artificial reef where there is swell - Scabs to Trigg. Although the stretch from The Point to Toms seems to pick up the same swell, and might cause limited disturbance to the beaches ?

GPA said...

^^^
Thanks for posting mazdon - it was an interesting read...

On a slightly unrelated note - do you happen to know what is happening with the potential artificial surfing reef that is supposedly part of the upcoming Ocean Reef Marina development...? There's not much info on the City of Joondalup website...

cheers- GPA

GPA
nothing except that they have dropped it from the concept design version 7.2.

http://www.joondalup.wa.gov.au/Develop/MajorProjects/OceanReefMarina/ConceptPlan.aspx

I've always thought the stretch from Floreat beach to Scarb is under utilised, and even Swanny to City too! I know we don't get any swell to write home about, but usually a decent wave closes out on the shore of the beaches I just mentioned, and it leads me to think 'if only I was rich and could anonymously dump a few tonnes of limestone out there'. Probably a silly idea though.

fuall said...

Would Surfing WA be able to get a grant for any studies?

Marmion Marine Park quote:
The marine park is managed under the CALM Act 1994 and any development in the park would require Marine Parks and Reserves Authority (MPRA) approval. To do this a formal proposal would need to be lodged and assessed. Developments such as a groyne extension would require at a minimum some modeling studies to determine potential changes to coastline morphology and water movement.

I bet none of that was done before Hillarys went in