I had to laugh when I saw the beach erosion article in the Manly Daily when they referred to Wetherill Point. I surfed there about 2 moths ago and I had to jump off the rocks to get out. It was kind of fun. Ive been surfing Narrabeen for 25 years and I have never seen the beach this eroded.
Finally the government are taking beach nourishment seriously and they understand seawalls and groynes are not the answer.
I thought a artificial reef to take the impact like they have at the Goldie....
What do you guys think of beach nourishment? Do you have any other idea's?
Below is the link to the Manly Daily
http://www.manlydaily.com.au/article/20 ... _news.html
Wetherill Point
Moderators: jimmy, collnarra, PeepeelaPew, Butts, beach_defender, Shari, Forum Moderators
Great topic.
I dont have a clue when it comes to this topic. I always wanted there to be a sick breakwall, but for selfish reasons.
Why would a breakwall or a groin fail? Is if from the shape of Longy somehow? The south swells would undermine the beach south of the wall?
Keen to hear what some people from the "RS brains trust" had to say about it.
I dont have a clue when it comes to this topic. I always wanted there to be a sick breakwall, but for selfish reasons.
Why would a breakwall or a groin fail? Is if from the shape of Longy somehow? The south swells would undermine the beach south of the wall?
Keen to hear what some people from the "RS brains trust" had to say about it.
the sea wall at dy is retarded, and now that the beach is gone maybe in future councils will take note?
what you need is something that absorbs both the wave energy and available sand. a hard vertical surface does the opposite in both cases.
so you get about 1000000000 2 foot deep terracotta pipes. you stack them with about a 50mm step for each level then tip them back to about 60 degrees. the result is a backstop that may get exposed from time to time, but will not undermine it's self. instead it will dissipate the wave energy and catch enough sand to slow the erosion. then when there's less surf, it will also catch sand from the wind until it overflows and gets buried again.
cheaper than an artificial reef or sea wall.
what you need is something that absorbs both the wave energy and available sand. a hard vertical surface does the opposite in both cases.
so you get about 1000000000 2 foot deep terracotta pipes. you stack them with about a 50mm step for each level then tip them back to about 60 degrees. the result is a backstop that may get exposed from time to time, but will not undermine it's self. instead it will dissipate the wave energy and catch enough sand to slow the erosion. then when there's less surf, it will also catch sand from the wind until it overflows and gets buried again.
cheaper than an artificial reef or sea wall.
The sand flow along the beach would be interupted and Northy would no doubt also be affected in some way as well.Coops@DY wrote:Great topic.
I dont have a clue when it comes to this topic. I always wanted there to be a sick breakwall, but for selfish reasons.
Why would a breakwall or a groin fail? Is if from the shape of Longy somehow? The south swells would undermine the beach south of the wall?
I guess sand would compact the beach, but at the expense of those occasional endless peaks down the beach in NE swells.
wanto, one of the "best" answers to sea walls I have heard.wanto wrote:the sea wall at dy is retarded, and now that the beach is gone maybe in future councils will take note?
what you need is something that absorbs both the wave energy and available sand. a hard vertical surface does the opposite in both cases.
so you get about 1000000000 2 foot deep terracotta pipes. you stack them with about a 50mm step for each level then tip them back to about 60 degrees. the result is a backstop that may get exposed from time to time, but will not undermine it's self. instead it will dissipate the wave energy and catch enough sand to slow the erosion. then when there's less surf, it will also catch sand from the wind until it overflows and gets buried again.
cheaper than an artificial reef or sea wall.
How did you come at 60 degrees? Any factual basis/documents?
Theoretically it would work nicely, anything has got to be better then SEA WALLS
Someone told me just recently that there had been a (national) study and if you don’t dump the SAME sand type, and let’s face it there is plenty of variety, the dumped sand will not stay.
Urban myth or anyone heard this? Wasn’t you who told me was it i-moderate-butts?
Let nature take its course, it will anyway or we pay the price. :?
Urban myth or anyone heard this? Wasn’t you who told me was it i-moderate-butts?
Let nature take its course, it will anyway or we pay the price. :?
like cronullas wall?wanto wrote:the sea wall at dy is retarded, and now that the beach is gone maybe in future councils will take note?
what you need is something that absorbs both the wave energy and available sand. a hard vertical surface does the opposite in both cases.
so you get about 1000000000 2 foot deep terracotta pipes. you stack them with about a 50mm step for each level then tip them back to about 60 degrees. the result is a backstop that may get exposed from time to time, but will not undermine it's self. instead it will dissipate the wave energy and catch enough sand to slow the erosion. then when there's less surf, it will also catch sand from the wind until it overflows and gets buried again.
cheaper than an artificial reef or sea wall.
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oldman
- Snowy McAllister
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I think you're right there Ric. The difference in the sand between eastern suburbs beaches and northern suburbs (of Sydney) beaches is substantial. I would suspect there is some truth in the theory that the sand won't hold unless it's the same.
I've got some piccies of the erosion of Norah Head, which is getting rather serious. Will try to put some up soon.
I agree that we shouldn't have any residential or other property within 50, or better still 100 metres of the beach, and the first thing on the land should be the car parks and the road that carries everyone to and from the beach, and before that should be the dunes with those impressive grasses that can grow so close to the beach on sand.
Alas, too late for that now.
I've got some piccies of the erosion of Norah Head, which is getting rather serious. Will try to put some up soon.
I agree that we shouldn't have any residential or other property within 50, or better still 100 metres of the beach, and the first thing on the land should be the car parks and the road that carries everyone to and from the beach, and before that should be the dunes with those impressive grasses that can grow so close to the beach on sand.
Alas, too late for that now.
butts, just a guess .. you want it steep enough so that waves that wash in don't wash out as easily
.. and flat enough that it can be made into a wall of sorts, because you can't have too much land taken up by it.
in fact, you could have it completely vertical ie reverse the 50mm step so that the pipes are angled, but the wall face is vertical. this would reduce the wave dissipation, but still be better than a sea wall.
obviously if a council is willing to put $M into it they would want to research the variables ahead of time, but a concrete sea wall is just plain stupid.
marcus re cronulla: i don't remember what it's made of ... is it the same? wouldn't surprise me as it's a pretty obvious solution. does it work?
.. and flat enough that it can be made into a wall of sorts, because you can't have too much land taken up by it.
in fact, you could have it completely vertical ie reverse the 50mm step so that the pipes are angled, but the wall face is vertical. this would reduce the wave dissipation, but still be better than a sea wall.
obviously if a council is willing to put $M into it they would want to research the variables ahead of time, but a concrete sea wall is just plain stupid.
marcus re cronulla: i don't remember what it's made of ... is it the same? wouldn't surprise me as it's a pretty obvious solution. does it work?
RV, nah not me :? Could've been Beach Defenderric_vidal wrote:Someone told me just recently that there had been a (national) study and if you don’t dump the SAME sand type, and let’s face it there is plenty of variety, the dumped sand will not stay.
Urban myth or anyone heard this? Wasn’t you who told me was it i-moderate-butts?
Let nature take its course, it will anyway or we pay the price. :?
Sort of stands to reason though, different granular size, different composite makeup, breakdown differently as opposed to others.
We need a geologists view, anybody got an answer for the different sand theory
wanto, well nice idea then
Remember seeing some documentary on somewhere (Japan maybe)about building a sea wall out of concrete stars
Apparently the design was to dissapate the force of the waves, but not destroy/undermine
the natural environment it was on. :?
As well as cater for 100 year storms, without having to build a monstrousity (??? spelling).
Never ended up seeing the end of it, but assume it worked.
NG or Discovery I think :?
I'm with you, Jimi.Jimi wrote:how about set up a 50 metre buffer zone around all beaches, meaning demolish any buildings within 50 metres of the sand. Then let nature swap the sand around from dunes, to the beach and to sandbars all it wants, beach erosion wont be an issue and it can continue to erode and deposit naturally
They should slowly continue with the council buy-back option.
Only trouble is Sartor is considering abolishing Section 94 contributions to look after his developer mates.
Keep 'em coming oldy.oldman wrote:I wish boozer. It makes a lot of sense, but politically difficult. Such a vexed issue.Boozer wrote: I'm with you, Jimi.
They should slowly continue with the council buy-back option.
More pictures will follow
A better perspective than the ones in the paper of Norah Head.
It's not as bad up Bilongil, but the properties up there are worth even more.
Piss poor planning.
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Mr_momo_32
- Local
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dunno about the weithril point bit 
but i don't think the council thought about their last sand dumping episode.
the sand that dumped formed a very stepp wall, this also screwed the banks.
seeing as the wall was steep it was wiped out in one swell. i think a wall with a flatter plain ( not steep ) would be much more effective.
i was againt the sand dumping in the first place and the see wall. although the rocks that are exposed at narra do a good job of containing the wave and tides.
but i don't think the council thought about their last sand dumping episode.
the sand that dumped formed a very stepp wall, this also screwed the banks.
seeing as the wall was steep it was wiped out in one swell. i think a wall with a flatter plain ( not steep ) would be much more effective.
i was againt the sand dumping in the first place and the see wall. although the rocks that are exposed at narra do a good job of containing the wave and tides.
I assume the sand dredged off shore will be deposited like they do at the Goldie, from the water so the sand can be naturally deposited and compacted by the movement of the ocean. Hopefully this compacted sand will build solid banks that can take the impact and dissipate the wave power before it has the chance to erode the shoreline. This is a better alternative to sea walls and groynes that upset the movement of the sand up a down the beach.
Wetherill st is usually the worst affected area, Im not sure why, maybe because the beach starts to bend around wetherill or the development behind effecting the wind moving the sand.
I was truly blown away how much sand was moved around in those last storms, Northy looked like it had snowed sand and Mona Vale was even worse with huge deposits in the car park.
I also have a theory about how close Collaroy Plateau is to the shore line, that it effects the wind movement, compounded by the development. If you look at the beach from the Marqueseas to the lake it hasn't been affected as bad as say collaroy to the Marquesas. Just a thought.
Wetherill st is usually the worst affected area, Im not sure why, maybe because the beach starts to bend around wetherill or the development behind effecting the wind moving the sand.
I was truly blown away how much sand was moved around in those last storms, Northy looked like it had snowed sand and Mona Vale was even worse with huge deposits in the car park.
I also have a theory about how close Collaroy Plateau is to the shore line, that it effects the wind movement, compounded by the development. If you look at the beach from the Marqueseas to the lake it hasn't been affected as bad as say collaroy to the Marquesas. Just a thought.
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