hey doggie, not sure where you are going with that, but if hillarys was a major blocker of sand transport, you'd see a massive build up on one side and serious starvation on the other - as is, there is not really an issue on either side except for the need for protection to the infrastructure close behind - hence the 3 groynes and a seawall in front of the surfclub. likewise there are no issues with needing to dredge the entrance, so the sand movement past is likely along the reef line, and bathymetry shows it flows in (or out) again at pinnaroo point (the island and the bathymetry of the reefs there seem to act as a control). friend of mine prepared a review of its impact on the sand movements just last year.

it actually seems like they lucked out with the hillary's placement to be honest, as opposed to say, Port Geographe?

fuall - SWA could apply to department of transport to get a 50/50 style grant for a coastal investigation - next round is in may to june this year.
They just need to contact the Coastal infrastructure group to get a feel for the scope of it and start a dialogue if they wanted to go down that path. or try searching "coastwest grants" and see if it fits in there scope.

MPRA is purely an advisory body made up of a diverse and knowledgable group of experts, who guide DEC positions on managing or building in marine parks. You just need to book a time to present them your argument/case, and do it well, but even if they approve or think it is a sound idea, there is no guarantee DEC will be convinced that it won't have a negative effect in the park, and they are the final approving org.

it would be interesting to see if there is a section under erosion with infrastructure behind worth saving, and then do a study to prove that a reef out front would disperse the energy and protect the section - and then run with it from there.

@mazdon any idea or reports on whats happened at watermans bay. council trying to save that toilet block and road. Is it just cyclical sand movement or results of hillaries?

doggie said...

Have you looked at the north side of Hillarys? And since Hillarys was built all the breaks south have been starved of sand and dont work the way they used to.
I watched Hillarys and the three groynes being built and saw first hand how the coastline changed after that.

hillary's has some accretion immediately north, but then an eroding point another 200m past that. Let me know your email doggie and i'll send you a report the City of Joondalup had done on it by a coastal engineer, looking at the accretion/erosion north and south from 1987 to 2000, and then 2000 to 2010 - that indicates there was accretion on BOTH sides in the decade after construction, but that the past decade this has slowed considerably.

i can't absolutely "prove" that hillary's is not to blame for changing the sand transport patterns to the south or north for as far as you want to go, but the evidence immediately north and south shows no major sand transport impediment compared to other sites in WA, or interstate, more like it was a point were sand typically travelled to from either way rather than a net flow one way or the other.

given sand transport in other places has started to be understood in decadal and even 25-50 year cycles of sand moving on and offshore (we just don't have good data and records going further back to exam it), it just seems to simple to me to blame it on one dynamic.

poida - the consultants who built the wall there had a brief to save the infrastructure behind it. As with any hard sttructure, you will lose the beach in front due to increased energy eg reflection of waves, in the long term, unless there is a constant sand feed (thats why some councils still have to dump heaps of sand in some places with engineered beaches etc). the consultant informed the council of this before they went ahead and built it. for what it is it works well, unfortunately it makes it harder for sand to get trapped in there. i suspect there was a feed of sand coming in from offshore for a couple of decades (picture how the spit formed at safety bay, coming in from offshore south of penguin island, hitting the shoreline currents, and forming the pond) and that the supply simply ran out? who knows really, anyone can tell you different since there really ain't much evidence to back it up - although city of stirling are starting to record beach profiles etc along these stretches to get adata base of the beach widths and volumes going which is a start.

incidentally, did you see how the sand shifted from the north side of that beach to the south over last winter? with the ramp out of the water end of summer, and then hitting sand by winters end when pushed back along by NWers? i haven't had a look in a while there though, but that is pretty much acting like compartments do between groynes, sediment is trapped and shifts between - but when you do get a really big blow and the sand moves offshore, you need the right conditions to move it back onshore or you lose it... or you need a bigger slower feed as an alternative... or the council needs to invest in sand mining!

anyways, i am off to paddle somewhere in the metro madhouse
enjoy your aus days

cheers

Mazdon I will PM you on Monday but at the end of the day Hillary's and the groins south of there have faaarkt it, sad really that the all mighty dollar rules us all

If less sand because of Hillarys, why is it that now (even in winter) Trigg "Island" is now full of sand, and rarely (if at all) becomes on Island

I remember (when a kid) exploring the caves in the Island, that are now full of sand.

then why do you say Hillarys is relevant to Trigg?

more sand at the point now than what there used to be (in my respectful opinion)

Yeh I am with Doggie on this one I grew up surfing all the northern reefs probably 50% of my surfs...they started breaking less and less good after the marina where now they rarely get epic. The beachies banks dont get as good either it never used to close out so much..The point used get sand right behind the reef...we are in the middle of summer and it is breaking at seconds...GAY..perth needs some answers to recreate and improve waves...

doggie said...

Have you looked at the north side of Hillarys? And since Hillarys was built all the breaks south have been starved of sand and dont work the way they used to.
I watched Hillarys and the three groynes being built and saw first hand how the coastline changed after that.

sadly Trigg etc aren't the only places effected by building and greed lads... a lot of development mandurah way has had a very negative outcome on many once good surf spots

I love going there on my goat boat, love having dust ups with the crew!

Haven't been there for a coupla years now as I have been Kiting more these days!

Might come down there with my OLD goat boat and take out a few "CREW'S" new boards!!

Hey Maz have you seen or have access to any annual average swell reports that go back the last 20 years?
That could show if we just arent getting the same sized swells anymore.

newguy said...

So is it wishful thinking that I can blame my surfing ability on the building of the Hillarys Marina affecting Perth beaches wave quality?

Nope. Move north or south of perth to surf every weekend. Come holiday time, go find uncrowded waves. If it makes you feel better, I don't quite have the same snap in my vertical turns that I used to - largely because I have a few injuries and I don't want to flare them up - but I have heaps more power and and ride the barrel waaaa-aaaay better at forty than I did at thirty.

So you will improve a lot over the next few years. Push your surfing and get out in what makes you a little nervous - lonely reefs, bigger waves, ledging tubes, backhand waves, forehand waves.

Be dedicated and keep the grommet stoke. I am sure you have seen surfing friends drift away from the sport already. It is a shame as it is an activity which is relatively mild on the body and you can do it a lot longer than you can play footy/basketball/cricket etc.

So the studys are wrong, as usual. They should just ask the surfers whats happening.

mazdon said...

what if the guys who did these studies are surfers doggie? and are trying to balance their experience with the surf spots, with what the data is actually telling them?

Are they though? I would doubt it. If the correct studies were done alot of beach front development would not have gone ahead. But why do studies that halt the development, that would make no-one any money would it!!

The only reason we have dune recon is so the sand dosnt blow onto Westcoast hwy and into rich peoples front yards. Go back 40 years and look at the pics of Trigg and Scarbough, look how wide and flat the beaches were then. Now they are steep boolsh!t beaches that creat backwash ect.

Go and have a look in Scarbough markets, they did have some pics in there.

Rant over for now..............

Dunno if i can arsed going to the trouble of getting on contact with those listed! Was just hoping you had seen some sort of report on it. Whatever the case is that Trigg/Scarb stretch certainly doesn't break like it used to and i have seldom surfed it the past 10 years since first surfing in the early 90's. And then again as Maz alluded to when i was 10 head high waves were 8 footers!! I remember when a massive winter storm came through prob about 15 years ago and tore all the sand out from Trigg point and exposed all sorts of rocks and reefs(i think even a plaque or something showed up??) that i hadnt seen before on the beach along with a 6ft drop at the end of the path, for me it was from then on the point never regained its reeling right hander.

And maz save those pennies up as i'd love a another trip back to oahu next december/jan, needed the comfort mate out there last month so i dont **** myself as much Keep up the technical posts too, it's good reading quality info from someone so knowledgable and passionate in their field.