Collaroy Seawall Faces First Real Test
Environmental vandalism or gross negligence?
At what point do we put an end to this insanity.
The Collaroy Beach seawall project was put to the test for the first time today with the arrival of a moderate to large east-northeast groundswell from ex-Tropical Cyclone Seth, coinciding with a king tide.
It didn't last long and within 12 hours the sand that was built up against the near finished first wall was 2/3rds washed away. It never stood a chance.
In their natural state, sand dunes are dynamic and in a constant state of flux. Building up during periods of low swell energy, while being transported into the surf zone during periods of high swell energy, acting as a buffer to the incoming surf. When a hard structure is introduced to the equation we see an increase in reflective energy and turbulence, slowing the accretion of sand while also accelerating erosion in storm conditions.
Adjacent a second wall constructed just to the north, the half finished revetment was torn to rubble with dangerous rebar, boulders and cement being washed into the surf zone.
The beach is now too dangerous to walk along and it's one big eyesore. Further to the north, sand that was built up in front of properties has been scoured away leaving an eight foot drop-off. If anyone was to slide down the edge during one of these high-tide swells there would be a high chance of being washed off their feet and dragged out to sea.
Comparing the swell to those of last year it wasn't of any major significance but it shows the futile efforts trying to protect property with a hard structure.
The only feasible way forward without wasting any more council and tax payers money to protect the properties in question is to acquire the properties at any cost and return them to a naturalised stated.
Over the coming fortnight there's a couple more swell forecast from the east-northeast and that'll really put the structures to the test.
Comments
"Environmental vandalism or gross negligence?"
Both!! Sounds like the beach will be off limits/ too dangerous to walk on for weeks until the NSW Beaches Council recovers the rusting rebarb & concrete waste scattered along the beach then?
...and the sick irony of the beach access sign detailing the seawall works with all "enquires to be made
the Senior Environmental Officer" Northern Beaches NSW govt!! Am I missing something with the job title there? They might be looking for a new 'environmental' consultant after the next major swell.
Whether the NSW state government / local council want to backflip with a pike on their current failing seawall master plan is another thing.
Jeez. Imagine the carnage during the next ECL.
What an absolute joke of a mess this has turned into. Lawsuit waiting to happen when a swimmer/surfer gets nailed by a rogue piece of concrete either down the 'Roy or up towards Northy. 100% agree Craig, the only option is to buy back the properties and be done with it like they should have done years ago.
Hear, hear! Absolutely spot on, Craig. The sooner we (as humans) acknowledge the nature of nature, and work with it instead of against it, the better for everybody. (As we all know, unfortunately, money/wealth/property seems to be many people's priority, and corrupt opportunists step in to "help" with that).
Craig Brokensha on the Sunshine Coast there is a similar 'future' proposal for a rock wall between Alexandra Headlands and Maroochydore beaches. A band of knowledgable people have gotten together and are in discussions about it and coming up with arguments and alternatives against it. Might discuss that with @surfriderfoundation and Surfrider Foundation Sunshine Coast, and those people and localised groups finding themselves in positions of having to fight this idiocy. Not sure why coastal ginger beers (engineeers) assigned by local councils just keep getting it wrong, but it would be fascinating to go through the meetings minutes of how these get passed, and the deceptive and misguided arguments that must be being put forward.
And more recently there was a local magazine piece discussing future sea level rises and the Noosa beach rock wall not being able to contain that, plus the homes along the Sunshine Beach to Peregian Beach stretch being at future risk, and councils would be needing to address that. Might chat about it at some point Craig Brokensha, and anyone with deeper connections or insights, feel free to pass me their contacts and we can compare notes and research and discussion points.
Cheers mate. JP
Jody thanks for mentioning this.
For the swellnet readers here's some background info, and here.
(btw if you're the Jody P I'm thinking of, you're an absolute legend mate!)
Isn't an extension to the Point Cartwright breakwall on the cards aa well?
Yes it is. I looked into this again yesterday.
Here's the Maritime Safety Queensland website link and here's what appears to be the numerical modelling report upon which a lot of decision-making on the issue is based.
Here's a screengrab from the website about the proposed breakwall extension:
It seems that the main concern about the extension is the interruption of the natural flow of sand onto Mooloolaba beach and hence increased erosion risk.
To add a bit of controversy, I've often wondered:
Is Carties borderline just a novelty wave?
Is Carties a perfect candidate for a coastal engineering and resculpting project that kills two birds with one stone: that fixes the harbour entrance shoaling problem and turns Carties into an actual quality wave...?
gsco, I'd have thought that the first hurdle for any enhancement - besides the environmental impacts - would be the issue of access and whether the investment creates something with the most benefit for the most people. It appears that because of the relative lack of access to PC, the equation would be out of kilter to begin with.
Will it make Carties better or will kooks just ride into the wall even more.
Craig - we are expecting you to be down there at High Tide 11pm tonight with your Torch and Box Brownie for some more pics
Nah wait 'til tomorrow mornings high.
Tonights high tide is 1.34m, tomorrow morning is 1.96m
Proven time and time and time again that sea walls do not work- period. But, they just persist time and time again.
In Japan, their solution is to just go bigger and higher . Fvck the coastline.
Jeez this angers me.
Thanks Craig aod if you are THE Jody P, yes you are a ledge. Fight the good fight mate.
Zen interested how Japan just keeps dropping those big Tetrapods anywhere there is coastal erosion...lost a lot of surf spots.....how effective do you think they actually are against erosion?
I first noticed them when I went to Nijjima island in the early 90's and asked what were they ...reply was to protect the land from erosion....they actually had the moulds for the TP's there and just kept making them when needed..
They're not effective at all mate. Wherever there's a seawall the sand/beach washes away and makes it virtually impossible to enter or exit the water, not to mention the impact on the birdlife, fish and crustaceans that depend on the seasonal sand flow that comes with a healthy beach.
I've written about it before but the real reason here is money- it is massive pork-barreling on an unprecedented scale. Basically the awarding of contracts falls across a couple of ministries. These contracts to the construction companies are worth hundreds of millions of dollars. The majority of these companies are legitimate businesses set up by Yakuza. The people responsible for awarding the contracts get huge kickbacks. More often than not, the pollies retiire and are parachuted onto the boards of these companies and live out their lives having enriched themselves quite nicely. It's corrupt to the eyeballs and the only winners are the crooked pollies and the dodgy construction companies while the once beautiful Japanese coastline is lost forever.
Also, it's a not so secret secret, anyone who speaks out about this have been known to disappear. More than likely entombed in one of those tetrapod molds you mentioned above.
I will try and find some pics of my area. It breaks my heart.
Wow Zen saw those photo's , it's really sad that they couldn't come up with something else , which raises the question....what other alternatives are there??
Not rhetorical question !
I can see everybody getting angry here on SN.....but what are the solutions to seal level rise , Short term and long term.
As you know we have the Great Ocean Road down here , which was a huge Tourist attraction ( before Covid.) a report a number of years ago by the Great Ocean Road Coastal Committee, GORCC...showed there were more than 47 areas that were of immediate concern where the ocean would cut the road. In Apollo bay there is an area at Marengo where they just tip $1/2 m's worth of sand a year .....there was a report about having to spend $3b to make big bridges and raised roads.......
the whole sea level/erosion issue is here now .....hmm any idea's solutions you have come across?
heres a rad idea for you,dig canal from coast to central Australia which is considerably below sea level and flood the interior.could also be done in death valley USA.now that could be a wave pool!!
Some investigative journalism required to obtain all the council documents around its approval process. The first application for a sloping structure was widely publicised and accepted by most who saw it. A sneaky second application, for the vertical wall was seen by very few. Then there is the question of the parameters given to the designers of the second structure. Northern Beaches councils have been sacked for dodgy dealing twice before. It has to be worth a look.
Oh boy, what a cluster-fuck.
bit of a worry but, when you buy a nice piece of land by the ocean in high risk erosion zone.....why do tax payers have to buy the property back,,,surely the owner knew the risks ?
We all know there is significant increases in sea level rise.....are we setting a precedent that if your coastal property succumbs to coastal erosion, you should be financially compensated?
How about dredging narrabeen lagoon?? Making it deeper? Holds more water and replenish the beach? Don’t lynch me it’s only an idea
I’m sure Fraser Island will give some back……..
Heard rumours that the Wamberal Seawall has got green light hopefully the central coast council read this article. IT WILL NOT FUCKN WORK YA FLOGS.. 5/6 NE SWELL NOW.. a proper ECL .. will destroy it .. this frustrates me ..
I was watching the houses on the cliffs at Bilgola the other day. They’re only a couple of hundred years away from
Certain death. Precarious!
As good as a house on the beach would be imagine how much more beautiful the East Coast would be with a 1km + building buffer from the coast depending on the terrain. Beaches like Bondi still had sand dunes and likely better banks all around.
A few pics. This is where I live. In one of the pics you see plant equipnent tearing up the beach in preparation for constructing a wall. In the others, you can see a part of the wall under construction. The fucking vandals bulldozed down one of the last remnants of coastal heath to get their heavy equipment in. In the other pic you can see the completed section of the wall. If you look a bit to the north you can see the relatively intact beach with a decent amount of sand. If you look further to the north you can see an old, crumbling seawall (due for replacement- fucking industry perpetuates itself) and you can see the water breaks right on it, there's no sand.
Please please please don't let those greedy fucks do this to Australia.
That's so shithouse I don't know where to start, Zen.
Shit....That looks like they are preparing for an invasion. What insanity!
Zen, it looks like an absolute disaster but I’m guessing it’s not so much about coastal erosion but more about tsunami mitigation??
First and foremost they say It's for erosion control but as you've seen after 2011 they did pretty much sfa. It's folly to believe you can hold back the Pacific. The thing is- in those pics, behind the walls, there's really not much to protect. There's no homes or businesses, or very few to speak of- doesn't come close to justifying the cost of the wall. All they are protecting are some pretty sparse land and some rice fields a couple of hundred metres inland.
that would be awesome location for JOb or other jackasses to film fun vids.
Great chat maka ya flog
This is a massive issue around the world from which there are countless learnings. Yet for some reason the Collaroy/Narra stretch seems to get flogged not only by mother nature but by poor coastal management approaches time and again. It's propped up by the NSW and local governments way beyond the importance or value of that stretch of private land. If it were replicated along vulnerable areas of the NSW coast (and that of other states) we would never be able to afford adaptation. It would be fascinating to see the NSW Cabinet documents which advocated for this approach.
However, Craig, when you say "Comparing the swell to those of last year it wasn't of any major significance but it shows the futile efforts trying to protect property with a hard structure." I have to disagree. My understanding is that the hard seawall was constructed with the specific intention to protect the private property behind the wall. In that regard it seems to have achieved its design objectives very nicely, and the sacrificing of the public beach (and public access/amenity) in front of it is just 'collateral damage'.
To my way of thinking, and with a working understanding of government process, the real issue is the approval process. This is the only plausible outcome from the hard seawall construction and the engineers would have known this. These impacts would have been explicitly tied to that particular design option by the engineers and other specialists involved. That this kind of construction was approved with the obvious impacts on the public domain (the beach) simply beggars belief, and the real focus should be on the process to consider the design options and then issue the approval. Avoiding these types of impacts has been part of state coastal management policy around the country for the past 30 years. It's a travesty in so many ways and a very poor precedent for other parts of the coast which will be deemed vulnerable to sea level rise.
True the seawall is doing its job for now but once those foundations and the back of it starts getting infiltrated...
Such a shame its job wasn't to conserve the beach and public access at the same time. The owners of those properties must have the most amazing collection of dirt on the political class.
With the benefit of ignorance, having not seen the actual plans, I'd be surprised if the foundations were able to fail easily as I'd expect they'd have been designed explicitly to avoid it. Having said that, nature usually finds a way to overcome most "permanent" human structures, and they often seem to forget that the wall isn't continuous....yet.
Good balanced post tango.
And in the approval documents was there a long-run cost benefit analysis evaluating the 2 treatment options of wall versus buy back and restoration. The option of do nothing seems to have passed but it can always be thrown in as a baseline.
Be interesting to know whether the assumptions for the modelling included any information on the value of the beach to be lost, belly. There's been a lot of work done to gain a better understanding of the value of the beach re both market and non-market economic benefits. When the CBA or risk assessment work is done with good information about the things to be lost (eg the beach, public access, amenity, etc) it can shift the outcome of the analysis significantly, particularly the "do nothing" which is actually doing something. It just doesn't make the engineering firms any money or contribute to gross state product under the current economic system.
Spot on. And I previously worked in a firm that did work in this area (it's not my specific expertise but I get the broad concepts).
There are some fed govt areas that listen to this thinking. I have limited state / lga experience but my perception is this broader thinking can get lost in short term self interest (putting it politely) as touched on by BB and others. Also I'm suspecting at the lga level the up front investment to do this work can be a hard sell.
Indeed. My experience is that if the responsible authority wasn't involved in the valuation process they struggle to comprehend it, let alone see how it legitimately applies to their own patch via things like benefits transfer. Such a shame.
Spot on tango. In this case there is evidence that the council and land owners subverted the approval process. The council now will not release the relevant documents without a formal application and even then would no doubt find reasons to withhold the significant parts. This was done to ensure the wall would be up before people realised what it was. People need to be absolutely on top of the approval process in their local area if they want to have a hope of preventing these structures. I posted links to the relevant council pages in the previous story.
That's appalling if it's the case, BB. Hopefully there's someone with deep pockets able to go after the truth of the matter. If a construction like that ends up being the only realistic option then so be it, but at least they need to be transparent about how they got to that point, and ideally accountable in future if it goes south.
BB has there been any attempt to take the process to the Land and Environment Court?
Cheers for the knowledge Craig. Went down for a look and it’s a fucken disgrace. The very thing we live for one the beaches is full of concrete and man made fuck ups.
One thing about mankind.
We can mess things up in a colossal way, and then keep doing it repeatedly.
How's that space travel and trip to MARS coming along, you blokes?
Are the exposed quarried rocks part of the construction/ foundation or are they from pre existing efforts.
Great article highlighting the competing interests of the natural environment and local councils (which are too easily manipulated by wealthy stakeholders).
Should this critical lens be applied to other topics such as the Coolum wavepool?
Needs another booster.
Hahaha
Thanks heaps for the update Craig. Really interesting [and sad] to see this story progress in real-time.
I do however feel there needs to be more separation regarding fact and opinion in your article. Also any factual statements need reference links to scientific papers backing them up if they are to be taken seriously
Statements such as the two below can only be classified as opinion unless you link to references.
"When a hard structure is introduced to the equation we see an increase in reflective energy and turbulence, slowing the accretion of sand while also accelerating erosion in storm conditions."
(This statement also doesn't specify what type of HARD structure. If you are referring to Vertical hard structures then that needs to be specified)
and the second last line of your article states-
"The only feasible way forward without wasting any more council and tax payers money to protect the properties in question is to acquire the properties at any cost and return them to a naturalised stated."
Again this can only be taken as opinion without proper scientific references.
Sorry to go hard on your story like that but I feel we need to keep the science at the forefront of all coastal engineering discussions. We all have valuable opinions, but they need to be separated from facts at all times, especially when it comes to Journalism.
Thanks again for your time and effort to make these articles, as we all truly appreciate them.
Thanks Lilas, totally get where you're coming from and taken on board.
Good point, Lilas, but I think the issues around hard structures and beach environments have been established for so long and are so well known in the coastal management field that it's taken as read. A bit like asking journos writing about climate change to include references scientific papers talking about how CO2 is a greenhouse gas.
@Tango
Sorry to sound pedantic but we should clarify exactly what we mean by "Hard Structures" as it's too general a term. [ask GaryG]
A horizontal reef is also a "Hard Structure" yet it acts in a very different way to a Vertical Sea Wall such as the Collaroy one. The angle of any hard hard structure relative to the wave direction is what really matters, so you can see why it's important to be very specific when talking about science/engineering.
Thanks, Lilas, I agree with there being challenges inherent in generalising, but I'm going to resist the temptation to take our shared pedantry down the rabbit hole this time!
It would be fantastic to see an interview with someone from Many Hydrolics as they did all the Scientific modeling and have been very open in sharing their data. The devil is in the detail and the more we understand the science behind it the better.
They have access to and use a large suit of software modeling tools, but unfortinately a lot of them don't have outputs that non-scientists can get their head around [just numbers which are meaningless on the surface unless you understand what they represent.]
Would be really good to see an article on the current state of affairs in the Coastal engineering world. This will give all all a better insight into what's going on with these projects.
Unlike politicians, scientists are usually very open with sharing their knowledge and data, to help inform the public
Yeah will chase that up.
what's the logic/law in having to buy back the properties ?
Apparently there was a buy back scheme that faltered in the early 1980's when the department of public works ran out of money. And since there's been no budget allocated for future buy backs.
The primary mechanism for coastal land acquisition in NSW has been the Coastal Lands Protection Scheme, but it wasn't designed for climate/erosion buy-backs. And it was created many years ago when coastal property was much lower in value and the bang for buck was much higher. As I understand it, governments have been reluctant to purchase vulnerable properties because there will be so many of them and the public purse could never afford it. Caveat emptor.....buyer beware.
https://www.planning.nsw.gov.au/Policy-and-Legislation/Coastal-and-marin...
Thanks Tango. Though..
"The scheme operates along the entire NSW coastal zone except for the Greater Sydney metropolitan area, identified as between Broken Bay (Central Coast) and the Minnamurra River (south of Shellharbour)."
So what applies through here?
Hi Craig, the short answer is I'm not sure as I have been out of NSW too long. I do know the metro area was excluded from the NSW Coastal Policy for a long time because it was seen as too difficult, and that the CLPS was focussed on environmental values.
There's been a lot written about the challenges of the various adaptation options, including the purchase of private lands. If Surfrider and others haven't done it already, my view is that Swellnet, as a legitimate media organisation with a substantial subscriber and stakeholder base, could very reasonably write to both the NSW Coastal Council and Sydney Coastal Councils Group seeking advice about the adaptation options and why buy-back was not considered suitable for the site. I'd be happy to help draft it offline.
lilas Manly Hydraulics did the work which was used for the initial design but I am not so sure about their input on what was finally constructed.
So whats your thoughts about using tax payers $'s to buy back endangered properties from natural erosion and as I asked Zen....are there any solutions other than just moving people property back from the Coast?
brutus Collaroy was not a typical situation. The council had an interest in preventing future erosion impacting Pittwater Rd, the main north-south artery on the NB. I think they saw an opportunity to get landowners to pay for something that they would very likely have to do at some point anyway. From their perspective building the wall before further erosion took place and moved closer to the road was another advantage as was disregarding the impact on the beach for a potentially more permanent solution. I suspect the engineering report will say that......if we ever get to see it.
So where public assets like roads are involved things get really sticky. We need to get all the data and expert opinions out in the open before decisions are made. This clearly did not happen at Collaroy.
Where the only issue is private property things are a bit simpler. My view is if it cannot be protected by environmentally sound methods then that is the owner's problem. The public should not suffer loss of amenity or pay the costs to protect it.
Buy backs should only be an.option when they contribute to an environmentally sound solution.
For those who may not know, the private land issue is complicated in NSW in particular (less so in other states) by the existence of ambulatory land boundaries which are set at various levels of the tide eg mean high water. As a result, if the sea erodes the shoreline (and the tidal level moves inland) it encroaches upon land once part of someone's private land title. This also creates problems when people try and keep claiming land as shorelines migrate seaward in times of accretion.
This paper by John Corkill is worth reading if you're interested - he's a legend.
https://www.sydneycoastalcouncils.com.au/sites/default/files/JRCorkill_A...(2)_Prop_L_Rev_67-84.pdf
yes, Blindboy, I am guessing they had absolutely no input on the final [or initial] design what-so-ever as they were only used as a consulting service by the Coastal engineers. As far as I know their job was to asses the designs given to them by the Coastal engineers, not to actually create any designs. [happy to stand corrected on any of this]
It would be interesting to know if coastal engineers are bound by law to follow best-advice from Consulting Scientists? Or are they just doing it like politicians and getting consultants to advise them and simply ignoring it and doing what they want as they are not bound by law to take that advice
Almost certainly the latter lilas, given the problems Sydney has had with apartment blocks I would think regulation is minimal to non-existent.
I asked a mate who works at MHL this exact question.
Confirming that they were involved in the initial design only.
Thanks Hazrus.
My NSW water buddy says MHL are coyboys. Honestly he might be correct based on the Manly erosion hahhaa
I like the cut of your pedantic job, there Lilas.
Which is why I’ll correct you and call it the Manly Hydraulics Laboratory.
A quick Google informs me that they are part of the State government, either Planning or Public Works, which was news to me because it’s mainly staffed by UNSW academics and is associated with the uni as a research centre.
The UNSW Centre is called the Water Research Laboratory. Operates out of the same premises.
Further reading from Sean and a concerned local named Terry- https://www.surfline.com/surf-news/theyve-kerbed-guttered-narrabeen-beac...
Same stretch of sand - another wall to “protect public assets” - https://www.scs.nsw.gov.au/soil-conservation-services-projects/collaroy-...
This issue isn’t a new development.
Gary G has been erecting hard structures in the dunes around Victorian beaches for years.
From the last set of minutes from the Wamberal Seawall advisory Taskforce Nov 18 2021
"Update from Council on possible site visit to Northern Beaches: Casey Johnston advised a site visit to Narrabeen-Collaroy is being canvased for early December 2021 to allow review of their seawall in construction.
Action: Casey Johnston to forward initial site visit details to Taskforce members, noting there will be a further site visit as the project progresses".
Wonder if he has been down there in the last 2 days to check on status of wall?
1922
Men sand-bag properties on Collaroy Beach – Arlington Building and a run of houses to the north – circa 1922. Photograph: Northern Beaches Council Library Local Studies
@Craig - Seem us humans have been doing dumb shit for quite a while now.
Maybe "Collaroy" is the aboriginal word for "Stupid White people"?
Yes, blowie, I've yet to see anyone our age advocating for a soft solution.
Old dude making a dash for it, budgie smugglers and a cricket cap. nothings going to stop him on his daily dip. What a mess. Nature fights back. Engineered to Australian Standards. High rises to sea walls. oh yeah and someone call security.
Good point, lilas, that explains the mystery of why aborigines didn't build their homes close to the ocean.
Councils of times gone by should never have approved houses to be built on the beach in known spots of erosion aswell as houses on the beach full stop as sand dunes have there purpose . Its no wonder the climate brigade aren't on board telling us all there garbage but erosion been around a tad longer than the 80s
Anybody heard of rising ocean levels & retreat by wealthy landholders who where allowed to build in the dune systems which nature designed to replenish the beaches? Go figure!
Some relevant links from when I had a dig around before. I have the mhl report but cannot find the link again.
https://eservices.northernbeaches.nsw.gov.au/ePlanning/live/Public/XC.Tr...
https://eservices.northernbeaches.nsw.gov.au/ePlanning/live/Public/XC.Tr...
https://eservices.northernbeaches.nsw.gov.au/ePlanning/live/Common/Outpu...
https://www.planning.nsw.gov.au/Policy-and-Legislation/Environmental-Pla...
https://eservices.northernbeaches.nsw.gov.au/ePlanning/live/Common/Outpu...
https://eservices.northernbeaches.nsw.gov.au/ePlanning/live/Common/Outpu...
This the report: https://files.northernbeaches.nsw.gov.au/sites/default/files/documents/g...
I'm just going through it.
Here's also the appendices and figures etc: https://files.northernbeaches.nsw.gov.au/sites/default/files/collaroy-na...
Yeah, cheers I've been through them as well.
You have a decade of good conditions somewhere along the way and everybody builds on the beach or on a river bank ...and then there reminded of the risks being swell generated by a low and annual big tides in cyclone season who woulda thought ..or flooding by jingoes ...fuk wouldnt you rather walk an extra couple of hundred metres and leave nature to do what it does .... stupid white poeple ..classic
Newiie Harbour was pumping. No fuckers complained about the rebar reef. Not even the dude came up with half an ear!
I definitely disagree with a buy back. Those properties are the responsibility of the owners. If they fall into the sea so be it.
I would rather have seen the money go into a couple of California style piers. This would reduce the lateral movement of sand along this stretch of beach, reducing the natural erosion while creating some great banks. Done well they could create added atmosphere to the beach life we love to live here for. At the same time it would put an end to the constant dredging and relocating of sand from Narrabeen
Lake that has been going on for the last 20 years.
Stop wasting money and do something that will achieve the intended goals. South Narrabeen beach is now useless to anyone. Surfers, sun bathers and swimmers. Including the residents behind the ‘great wall’.
Nice one Northern Beaches council.
Unfortunately groynes or artificial headlands are not part of the certified Coastal Zone Management Plan CZMP (2014).
Has any one ever suggested an off shore reef, seems like a win-win or is the sea floor unsuitable?
Mentioned in a previous article (linked below) - the region hosts submarine cables, so it's part of the Northern Sydney Protection Zone.
https://www.swellnet.com/comment/772908#comment-772908
Ben, yes there are submarine cables and the protection zone is there to prevent damage to the cables, but I don't think that would preclude construction of reefs, it just means that any proposed reef design/construction would have to be in consultation with the cable authorities.
The GCCC's Palm Beach Qld solution which uses an offshore reef/sand nourishment/seawall buried in the dune is the ONLY solution for coastal erosion that protects both beachfront private property and public property ie the beach, without any structures being visible on the beach. That is why this option was selected for Palm Beach Qld, and I think should be considered for all the other coastal erosion hotspots along the NSW coast as well. No-one wants to see visible structures built along the beachfront.
Re: "I don't think that would preclude construction of reefs"
My comment in the other article also notes that across this region, "it is illegal to establish, maintain or use a spoil ground or other ocean disposal point (including dumping materials at sea)".
The sheer number of cables there suggests to me that an offshore reef proposal would be unsuccesful.
A shame too, as it would probably be a good strategy.
I've looked at the general location plan of the cables and it seems there is a good say 500m- 1000m distance between groups of them along the beach, and they are buried for the first 500m out from the shore, so I would say there is a good chance of working within those areas in consultation with the cable authorities. The main issue is that the cables are protected in whatever is proposed. It would be the same as for any development adjacent to the cables where they make landfall. The seawall is probably built over them.
Gold Coast City Council had a similar problem to Collaroy at Palm Beach Qld.
The Gold Coast has undoubtedly the most at risk coastline in Australia.
Their ultimate solution was a combination of 3 things- a rock boulder seawall buried in the dunes as a final line of defense in extreme erosion events to protect private properties behind (this seawall actually runs for the full extent of the Gold Coast nth beaches but is rarely seen as it is completely buried under dunes/vege), an offshore reef, also rock boulders, to attenuate wave energy under normal conditions thus widening the beach in its lee, and lastly- sand nourishment, adding more sand to the beach system. The reef/sand nourishment are both mainly designed to widen and protect the public property, ie the beach, in front of the buried seawall.
GCCC's approach protects both private property and public beach amenity without any visible structures on the beach.
Other than buy the land and let nature take its course I’m really interested to know if there are any other options - not brutal like this but that might be effective ? Any example around the world that have worked with out wrecking a beach but holding back erosion in built up areas ?
Separately at the Collaroy pool end of the beach when the walk way became unstable they just craned in these massive bags of rocks on top of each other and said ‘job done’ - ugly as fuck. They also recently dug the mother of all holes in the sand and put huge foundations down ( well over a years work) for what I thought was further erosion work but turn out to be a access ramp for beach who can’t step down onto the beach. Didn’t hear boo about that from anyone ?
Thoughts ?
Hi Lost, yes there is another option - see my 2 posts above. You don't have to look around the world because the Gold Coast has implemented the only effective "non- ugly as fuck" option at Palm Beach Qld. There is no better option. Cheers
Bite the bullet and start buying the properties back and bulldozing them. This strategy had been used in other parts of the world where poor planning placed buildings too close to the ocean. Florida is an example. High rise apartment buildings demolished when they realised it was the most cost effective and environmentally sound long term solution.
Yep. And cap prices for market value pre 2000. And that’s being generous. You should’ve known by 1990.
The whole buy back argument being too expensive is a crock of shit. They have just set a precedent for the whole east coast of poor me multi millionaire landowners to set up squeaky wheel collectives. Maintenance starts 2 months (?) info a new build now paid by the public purse.
Perhaps off topic in relation to the above story but thought this video was interesting in regards to how certain structures change the amount of erosion and inundation behind structures from wave/tidal run up.
Yep, prevents over-topping but how's the reflection and enhanced rebound wave back into the surf zone!? A much higher amplitude as well.
That is the most ridiculous thing I have ever seen, hope they don't actually use that pathetic demo to help make a decision on what is going to be built to stop erosion.
Yep totally agree. which is why the video is so interesting. Shows what not to do, i mean it'd have some value in an inlet or lake subject to openings to the ocean in storm surge/high tides. But thats about it .
That video represents a nightmare scenario, no beach, no waves and similar to Zen's story ie man made interference gone wrong. Can't understand why more engineering research isn't focused on solutions further out in the water to dissipate the swell energy before it reaches the shore at full speed.
It makes perfect sense doesn't it, stop/dissipate the energy before it has the chance to have an impact. Look at offshore reefs around all the pacific islands. Aside from high tides and Tsunamis, Im guessing most islands/atolls dont suffer much erosion when surrounded by reefs?
Actually I do understand why the council doesn't research an alternative to a concrete wall, because it's easier to build a wall, something humans have been doing for thousands of years, we're good at it. It certainly doesn't make it the best decision though.
Contrast man-made against a natural barrier like mangroves (apologies for the sound, not my video)
That's awesome.
Trees work well for preventing erosion ONLY when the wave power is very minimal.
I'm a huge tree-hugger but they will not stop powerfull ocean waves. The also don't grow in sand so they won't be of any use to prevent coastal erosion on our open-ocean beaches
100% I just enjoyed the vision/video.
That’s awesome.
My parents in NZ were excited when they took out “bloody”mangroves at the mouth of the estuary where they lived.
“Just ugly, clog up the waterways” etc.
A few years on when I visited I suggested a stroll along the cliffs at the estuary and they replied that it’s to dangerous now as there’s been heaps of erosion for some reason. Lol.
They needed see this, but still probably wouldn’t t have believed it.
Edit: The estuary was in an area protected from the ocean and the cliffs only faced small wind chop and the tides.
Rad demo john interesting as Craig said to see the changes in shock waves returning seaward.
Not off topic JS, wouldn't be surprised if there is a hyperlink to that video in the sea wall approval document!.
We have trouble performing numerical analysis on complex near shore environments, so what we'll do is create a slab sided wave tank with perfectly geometrical structures and wave forms and see what "actually happens". Isolated, desk top engineering at its finest.
@dawnperiscope
Seems from my research, we have actually made a lot of progress towards physics-based numerical modeling of near-shore/beach environments in the last 20 years or so.
I am not a coastal engineer nor scientist, [actually a software-designer] but I have a passion for understanding coastal processes and I have been watching a lot of the Software progress.
There are many software suits now that can handle very complex near-shore modeling, including sediment transport from wave and current action.
The software built for Kelly's wave pool was also a big leap forward to modeling actual breaking waves and I really hope they share that knowledge with the rest of the scientific community to help forward our understanding.
I recently tested an Open-Source Wave modeling software called "Celeris" and the result are really good although I didn't go too in-depth with it. It only does BOUSSINESQ wave interaction and NOT sediment transport but you can still get a lot of good design-feedback
https://www.celeria.org/
It's actually quite simple to install and get going unlike a lot of open-source software.
The best thing about it is that you can output actual 3d animations of the simulation so that EVERYONE can understand the results. Scientists need to be able to communicate the results of simulations/tests in a way everyone gets, not just a bunch of numbers
Thanks Lilas,
Sounds like you are pretty deep in that world!
My comment was maybe too obscure but was meant to be sarcastic.
Point being that the experiment is a gimmick as it would be quite easily modelled in a software program given all geometric surfaces and the regular wave pattern.
@dawnperiscope. Apologies for misreading you.
Here's a screen grab from that video..
3-4x the wall?
Yep pretty significant increase in the height. Imagine how fun that'd be with your mates on a boog. Rock barrels at its best!
Shit that screen grab is Wild pic
Same concept as the Swatch Wave Tour?
Man, that'd get old real quick, happy to pass.
Collaroy in 1905 (middle left).
Notice how wide the beach was.
Why would you bother acquiring the affected properties "at any cost", when they're likely to be washed into the sea? It might be cold comfort to the home owners, but there's always a certain risk to be taken, anywhere you might choose to live. "I really like living here deep in the bush, close to nature. But if I get burnt out, then someone's going to be held to account"! "We haven't had a flood here for 20 years you say. I guess that the levees will give me a 100% guarantee that it'll never happen in my lifetime". "Have you ever seen such a magnificent view as the one from our balcony overlooking this active volcano? And there's no risk. The council will buy me out at any price if things get too hot".
Well now we know who is responsible for this debacle. Make his name famous: Peter Horton.
https://www.northernbeaches.nsw.gov.au/council/news/whats-happening-coll...
Here are the bloke credentials
https://www.linkedin.com/mwlite/in/peter-horton-coastal-engineer
This would be a better solution, I think.
Interesting to see if the slowed (design of) sand migration has had any knock-on effect for the likes of Tallebudgera- Burleigh and beyond. Is it designed to behave like a bottle-neck? If so, I presume it may slow around the reef, but then continue north on a more normal migration speed. Will this mean sand depletion north and a build up south?
The Palm Beach artificial reef is now completed.
https://www.facebook.com/watch/?v=144437777895204
Great article.. https://www.smh.com.au/property/news/coastal-properties-at-highest-clima...
@Craig
I recently moved house [Northern-Rivers nsw] and seal-level rise was a very serious consideration of mine.
It may not happen in my lifetime [fingers-crosssed] but it's a real issue when thinking about your children who eventually inherit your home.
I am safely 140m above sea-level now so that should be safe...for a while ...hahaha
Ha, that should do it!
@yeti. Great stuff. Posted the story from that link here.
We spoke to expert coastal engineer, Peter Horton, about the current situation and the coastal protection works he designed to protect the properties from large and powerful surf.
>> Quite a worrying statement to begin with. If he is an expert and this is what he designed, then I shudder to even imagine what the non-expert coastal engineers would design.
Mr Horton said there has been some very minor erosion at Collaroy/Narrabeen Beach this week, along with other NSW beaches, but it is not a cause for concern.
>>Is that because he has been paid already??
“This is associated with above-average wave heights related to Tropical Cyclone Seth and also elevated ocean water levels associated with very high tides,” Mr Horton said.
“The erosion at Collaroy/Narrabeen Beach is not particularly significant, unusual or surprising. There is no evidence whatsoever of accelerated erosion seaward of these newly constructed works.”
>>How can you say there is no evidence unless you have the facts to prove it? Have you done a study already? Sorry Peter but we can't just take you on your word for it.
Mr Horton said current conditions have exposed a temporary rock bund that was put in place to protect the construction site, but it will be removed when works are complete.
>>Really dumb idea. That's the only thing stopping all the sand at the base of the wall getting washed away.
“It's only a temporary feature. The contractor is required to remove this temporary working platform and bund at the completion of the works, sieve the sand and remove all debris, and return the beach to its former state.”
He said when the work is complete, sand will be pushed up to cover most of the seawall.
>> and the ocean will wash it all away again in the next big swell.
Like I said at the start, IF he is an "expert coastal engineer" then we are in a much deeper hole than I imagined.
sea wall is perfect. the above-average wave heights and elevated water levels are to blame.
My 2c on the buy back scheme - NB Council won't have 50+ million sitting around to buy them all back at once (and NSW Gov wouldn't be in a hurry to give them the rest) so they'd have to do it say a couple per year, but at the same time, that leaves the others who can't be bought back vulnerable and at risk of further destruction if another mega storm decides to show up, which in the current climate you'd have to think is pretty likely. You'd think that would then open it up for more legal action (aka why did ABC get first dibs and XYZ missed out?).
I reckon the chances of another solid E/NE Cyclone swell event this coming Summer/Autumn is very high with the second cyclone in as many weeks about to impact the coast and we are only 2 weeks into January....the other issue I'm sure Council would have faced "IF" they approached the home owners on the strip regarding a potential buy back scheme, my money is on most of, if not all of them being of the rich w@nker type mindset that will refuse to leave unless they get 2-3 times market value, degrading the process even further.....
It's going to be interesting to see how it holds up after this weekend/early next week with another round of resonably solid E/NE cyclone swell hits......who's going down to take more photos and show the aftermath?!!
That's assuming the properties are still worth something to the market. I suppose there are still those with more dollars than sense, but for me, the land is as good as built below the high-tide mark. Hence, they are of no market value to me.
Nah, buybacks don't put the properties back onto the market, they're acquired by the council at market rates and then emptied, returned to parkland and foredune, both a buffer against storm action.
Yep. For the most part I understand buybacks but, how will they appraise the value of these properties? Market value is driven by what people are willing to pay for it. If they are falling into the ocean or they require extensive works or continual maintenance, then what is the market value? Who is going to want to inherit that when they exchange contracts? For me, the value of these properties is in the negatives and at the very least, its a big fat round calamari.
Good point, however wouldn't a potential buyback theoretically drive the price up? Just like when the stock price of a company increases because of a speculated takeover bid.
I assume this would all depend on the power of the state government/council etc to cap buyback prices, similar to land buybacks for roads, airports etc.
Usually done by compulsory acquisition with the government working off existing market prices. Some family recently went through this as their house sat above the construction zone for the Spit / Northern Beaches Link tunnel. Not much wriggle room for negotiation, and in a volatile market owners are more liable to be offered (and it's an offer they can't refuse) recompense that sits at the lower end of the scale.
My experience with compulsory acquisition had to do with a Sydney motorway a few years back. The State Government essentially provided the compensation for the business to relocate to another 'suitable' site. The thing is, the existing site was fine except a motorway was about to be built straight through it. However, the bean counters and quantity surveyors were extremely difficult for obvious reasons. This is very different to Collaroy. Collaroy's existing situation is precarious at best. Has been for a while. Same old issues, with a more educated market. Existing market value must take into account that houses have erosion problems. The houses up the dune with no apparent erosion would be an apple compared to these lemons (for now). The market knows this. Insurance companies know this. The market knows the insurance companies know this. The council knows that the market knows the insurance companies knows... I dare say the neighbours are on notice too. Bean counters at the local council know this too. Perhaps at best, the council acquires the land and owners get a sum to relocate to a 'normal' house west of Pittwater Road (god forbid). If no acquisition or buyback is made, then good luck to the owners trying to sell these properties. There's only a loss to be made for the purchases.
I am not stock market savvy. I avoid it because I dont think anyone truly is except for a small % of big players who manipulate the market (or act like the house) and the rest just ride the peaks and troughs. I liken it to a form of gambling. But, I think its just basically supply and demand. You got to have demand/competition in order for a buyback to increase value of supply. I doubt there will be a demand for the effected given the inevitable. It's like companies using buybacks in a crisis. The council will be the lone 'interest'. When deciding to spend rate payer dollars, on what metric do they use without using the big IF ? That's a form of speculation I believe.
Hi Mark. If they ‘approached’ the landowners then the most they would be offered is market value. Nobody there is in a position to offer 2-3 times market value. The exception of course is if you’re a donor to the LNP then a $3M block of land can be sold for $30M!!!
I’m not sure that councils have the legal authority to ‘acquire’ the land, pretty sure that resides with State governments and the Feds only in certain circumstances. State govt has been acquiring properties for more toll roads of late and they have been getting low-balled big time, totally screwed over. You can go to court to complain about the price, but you can’t object to the acquisition. That’s just a done deal.
The problem is one of ‘vertical fiscal imbalance’. That means that the Feds have all the money, the States some and the councils bugger all. This is a big money problem way beyond the scope of local councils. The Feds and States are the only ones with sufficient means to do anything, but for them it’s a case of ‘not my problem’.
For Sydney it’s not just beach suburbs. With increased ocean levels comes all those properties around Botany Bay, Parramatta river, George’s river. All of Ramsgate, Brighton, Kyeemagh, Dolls Point, Scarborough Park and lots more will be underwater in 50 or 100 years time. (Those suburbs are just local ones I know a bit about. That’s tens of thousands of homes)
Guess where that temporary rock wall has ended up!
Liability..
Tetrapods work but don't protect the adjacent beach very well unless there are multiple groynes. Anyone who has been to Chiba in Kanto will have seen the Tetrapod formed surf breaks there.
2 metre swell at 13 seconds combining with a 1.8 metre high tide at nearly 9am should provide some good viewing this morning.
It's going to be carnage there this morning & yesterday afternoon even, solid 6-8ft sets on a big high, anyone heading down for a look?
abc news article today for more erosion https://www.abc.net.au/news/2022-01-17/will-climate-change-put-an-end-to...
I'm invested now, and want to know the latest. Any chance of a dedicated ErosionCam, Swellnet?
Well, it (and a lot of us) could possibly be in for a real test within 3-5 years with the Thwaites Glacier (Doomsday Glacier) suggested to be at risk of sliding into the sea and potentially raising sea levels by 65cm. Pretty incredible and frightening stuff.
That ABC article is spot on when it comes to waterfront properties. Unfortunately, what we see in Collaroy might become a norm to protect this lifestyle. Water is manageable but comes with a huge expense and loss of nature. I cannot see how can this be a feasible long-term strategy from the cost perspective. Surely, private properties can be protected but public amenities will require huge ongoing costs to keep up with the public requirement (sand nourishment is the first thing that comes to mind).
How’s the Seawall holding up? Surge and erosion even on protected beaches on the Mid North Coast today is nuts.
Looks like the council are aware of the liability concerning the still submerged rocks. Though they were quick to remove signs only recently erected on the beach..
https://www.smh.com.au/national/nsw/council-was-asked-about-danger-signs...
To be replaced with signs "Collaroy artificial reef project 2023"
This is a glimpse of what a beach could be; following sensible Council planning; (post storms in 1974) eg. development, carparks & roads behind the hind dunes leading to biketracks, walkways, supporting the community including
30 years of volunteers doing Dunecare (eg. walkways to viewing platforms & beaches, selective weed management, planting, education, etc)
(This dune area had been impacted by massacres, logging, cattle grazing & sand mining; then hit by huge storms in 1974, vandalism & arson)
Give nature a chance, it will rebound & stabilise dunes or else find a new equilibrium....< inland