Hello Jennifer,
I have been a reader and minor contributor at your blog over the last few months.
A few weeks ago I was discussing the Coorong with another commentator in relation to the Prime Minister’s new $10 billion National Water Security Plan in particular the hyper-salinity aspect.
With all the talk of the Murray “dying” I had thought the hyper-salinity was due to lower flow from the Murray River, the direct implication being less dilution of the Coorong as well as not being able to keep the mouth open.
As an irrigation farmer it is not pleasant to be accused of being partially responsible for destroying the Coorong.
Having been across the barrages and seeing the Coorong first hand late last year, meeting affected stakeholders and talking to South Australian government officials, I couldn’t help but feel it is the right thing to send the Coorong more water and thus that I should support the $10billion plan in its aim to buy back water for the river.
However, if my interpretation of this report ‘A Paleaecological Assessment of Water Quality Changes in the Coorong, South Australia’ is correct, the actual water from the Murray River has had no noticeable influence on the Coorong.
In fact, according to the report:
“Before European settlement the northern lagoon of the Coorong was dominated by tidal input of marine water. Marine flushing also strongly influenced the southern lagoon but less
frequently or to a lesser extent.
At no time in the 300 years before European settlement has the Coorong been noticeably influenced by flows from the River Murray.
The northern end of the southern lagoon occasionally experienced hypersaline conditions in the 300 years before European settlement. Elsewhere in the Coorong, the salinity was typically at, or below, 35,000 mg/L. In the southern lagoon the presence of diatom and ostracod taxa preferring salinity levels ~ 5000 mg/L suggests regular freshwater input. This source is likely to have been from the south-east.” [end of quote]
The report also states that “the extended presence of marine diatom taxa in Lake Alexandrina suggests the tidal prism regularly extended into Lake Alexandrina throughout the last 6000 years”, which I take to mean long periods of low flow where the mouth evidently did not close but rather was flushed by the sea.
What few people now realize is that there are barrages, construction completed in 1940, across each of the five channels connecting the lakes with the Coorong. These barrages restrict tidal flow into the lakes and stop freshwater flowing out of the Murray River’s mouth.
So effectively we might spend billions taking water from upstream irrigators and in the process displace jobs/communities and achieve nothing for the Coorong.
I do realise there are other “iconic” sites on the Murray that will benefit from more water, but they benefit already from the environmental nature of water deliveries prior to extraction, and don’t require 1000GL of fresh water evaporation from the lakes in low availability scenarios.
I now wonder if the most natural thing we can do for the Coorong is to remove the barrages and allow tidal action to do it’s business in particular flushing the Coorong. If this study by Adelaide University is correct the fresh water from the Murray River is not what the Coorong needs. It needs to be flushed by the ocean and this would be facilitated by the removal of the barrages.
Using stored fresh water from upstream to keep the mouth of the Murray River open, as currently advocated by various environment groups and the federal government shouldn’t really be an option.
There is currently a proposal to build a weir on the river at Wellington which is upstream of the lakes.
Irrigators currently dependent on the Lakes would have to be supplied from water upstream of this proposed new weir, much to their benefit by getting better quality water. Funding under the new $10 billion water plan could allow this to happen.
If we don’t get significant inflows the weir at Wellington will be built, the lake levels will fall and the irrigators won’t be irrigating anyway. But the situation at the Coorong will not improve unless the barrages are removed or opened.
If we do get substantial inflows, what was the problem again?
Cheers
Rojo
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
This is dynamite, Rog. I don’t know where to start listing all the green myths that this study blows clean out of the water.
First we should note that salinity of 35,000ppm is the salinity of sea water and the fact that sediments in the northern lagoon shows salinity levels of 35,000ppm for the past 500 year and possibly 2000 years makes it very clear that the term “once mighty murray” is so out of date as to be a more appropriate reference to conditions in Gondwanna Land.
And while the study makes it very clear that annual sediment layering has increased since eurosettlement, the claims that erosion in the Murray Darling Basin is severe have been demonstrated to be complete bollocks. Recent sedimentation layers are only 3mm a year and if this 3mm is spread over the area of Lake Alexandrina, and then divide that by the area of the entire catchment, and it becomes very clear that actual soil loss/ha is very low indeed.
The big issues are;
Past parliamentary inquiries into the MDB are all, essentially, based on false assumptions about the normal or natural state of the river system.
If the new Minister for Water, Mr Tunbull, were to continue with plans to manage or “restore” the river system based on any conclusions reached in previous misinformed inquiries then he would be not only guilty of an improper exercise of power but also a grossly negligent exercise of power.
The existing assumptions of natural flow, being the same as current mean inflows of 24,000 Gl, are demonstrably false.
The total removals of water for irrigation etc, amount to 11,000 GL, and if original flows really were in the order of 24,000 Gl then the volume of silt deposition at the mouth is more likely to have reduced rather than increased.
The green movement may be able to claim that there has been some increase in sediment loads but the transportation of these loads to the river mouth is still primarily dependent on water volume. Generally, the greater the discharge volume, the thicker the sediment layering.
So the fact that sediment layering has increased since eurosettlement also indicates that catchment runoff volumes have also increased considerably due to increased water yield from clearing.
It should also be noted that much of the irrigation and urban extraction in the system comes after it has contributed to increased river flows. Adelaide’s water flows all the way down to Morgan before being extracted and while it flows it is still transporting sediment down stream to a point where a later modest flood surge can more easily shift it to the river mouth.
What all this tells us is that the “Murray in Crisis” story is nothing but a green invented urban myth. Ripping of more farmers to use fresh water to “restore” imaginary conditions that never existed is the height of malgovernance and injustice.
The simple facts are, as I have stated on this blog numerous times, that the Murray Barrages would never have passed even the most rudimentary development assessment process, let alone a full Environmental Impact Assessment.
They do not provide a reserve water supply to Adelaide as they were originally intended to do. And they now provide little more than very expensive, environmentally damaging, second rate landscaping services to a minor regional boat hire industry that may actually benefit from an improved local ecology if the barrages were removed.
And the other service they provide, that of delivering a pretext for urban greens to inflict as much damage as possible on Australian farming interests, has no valid place in either valid environmental assessment, proper delivery of government policy, or the delivery of justice and equity for all of the community.
Thanks for posting this, Rog, well done.
Sorry, well done ROJO, not Rog.
What twaddle on erosion – all depends on the ability to move that sediment doesn’t it. Google deposition ratio. It’s a big catchment our MDB. Ian you’d apologise or mythologise your way out of anything.
And what’s your basis for your stated assumption of pre-European flows? What’s the derivation of the numbers?
Dead rivers gums galore and a river full of carp and surrounded by a countryside of very average land management. Keep spinning it. Someone might believe you.
Extract from Sim, T and Muller, K (2004) A Fresh History of the Lakes: Wellington to the Murray Mouth 1800s to 1935.
http://www.rivermurray.sa.gov.au/pdfs/FreshHistory.pdf
“Prior to European settlement, Lakes Alexandrina and Albert at the terminus of the River Murray were predominately fresh, with river water discharging to sea and keeping the Mouth clear. Contrary to what many believe today, saltwater intrusions into the Lake environment were not common until after 1900 when significant water resource development had occurred in the River Murray system.
Before large-scale extractions of water, the Lakes and lower Murray were rarely subjected to seawater invasions. Long time Goolwa resident Edward Leslie Goode told an enquiry in 1933 ‘I can remember when it was a remarkable thing when saltwater came up to the Goolwa wharf. Now we see saltwater in the lakes for months’.”
http://www.rivermurray.sa.gov.au/pdfs/Lakes%20History.pdf
not, so you prefer anecdotal evidence? I’ll put a little more credence in a uni study using actual sediment deposits.
Ian , the report attributes some of the sediment increases to the wave erosion due to the artificial level of the lakes.
So now “boy wonder” (aka Luke) wants to challenge the basic volume/velocity parameters of sediment transport?
The river length and width hasn’t changed so the only thing that would increase the capacity of the water to transport sediments such a long way is an increase in volume, velocity or both.
And as for Sim and Mullers, “Contrary to what many believe today, saltwater intrusions into the Lake environment were not common until after 1900 when significant water resource development had occurred in the River Murray system”.
Bollocks. compared to what took place after the completion of the Snowy Scheme, any diversions that took place between 1900 and 1933 were of zero relevance. It would also seem necessary to point out that 1900 to 1925 was a very dry period so we can reasonably assume that our complainant was doing the standard down streamers winge about anything going on up stream.
It is incumbent on “Not” or his authors to give us an accurate estimate of water extraction from the Murray from 1900 to 1933. We wait with baited breath.
Jeepers turbo-envelope – with the flow of the rivers and number of sediment traps along the system why do you think Lake Alexandrina would show the effects of erosion from all over the catchment.
As far as inflows are concerned – do you know that that tree clearing flow additions are not already factored in?
Funny how Ian adapts to uni research when it suits him – are you sure like most other research that you lampoon and harpoon that it wasn’t done by spivs or flesh crawling greenies. Where’s your consistency?
Readers interested in some strategies should have a good look here
The Draft Lower Murray Management Plan – April 1999
http://www.lm.net.au/~lmiag/downloads/lwmp_manual/draft_lwmp.pdf
The Murray would have to have the most artificial flows of almost any river in this country. How many dams, weirs etc are there along its length? Total volume of water flowing down the river is greater than ever with the additional releases of environmental flows, snowy scheme water and increased run off due to land clearing. Sure inflows are low now but if it wasn’t for the regulated nature of the river it would have dried up by now during this drought.
One would imagine that once the river stopped flowing and in the absence of the barrages sea water would have innundated Lake Alexandrina and others near the mouth of the Murray.
Luke, the trees along the Murray are in stress not because of global warming or this drought but because the pattern of natural floods have been altered to such an extent. Whenever the river has been allowed to flood the river red gums a rapid and positive response has been observed.
Also river red gums are well known (as are many other Eucalypts) for dumping foliage and branches beyond what is needed for basis respiration in times of stress. It does not mean thatthe trees are dying rather that they are utilising a very effective adaptive mechanism to survive this current drought.
Rojo/Ian
This is interesting but I see Luke has waded in out of his depth again, (I spent not a few months researching laminar and turbulent flow in water courses to understand how heavy minerals are transported along water courses, in addition to setting up experiments to measure heavy mineral dispersion at two localities in the Kimberley Region of WA.)
I suspect the whole issue involves Quaternary studies?
And I would also question the idea that rainwater excavates rivers in rocks.
Bit of a tease here, and contact me directly as I am bush for 3 weeks next week.
Whoooaa Peter; stop pulling my leg!
“Total volume of water flowing down the river is greater than ever with the additional releases of environmental flows, snowy scheme water and increased run off due to land clearing”
1) the environmental flows today were only saved by damming normal runoff in better years
2) Snowy waters and other major storages were put there primarily for irrigators who allow most of it to evaporate
3) The run off and storages all decreased with much higher evaporation in recent times
4) Inflows from alpine regions decreased due to climate change and global warming
The sea barrages only became necessary after massive diversions for irrigation way upstream. They also allowed irrigation by flooding of the swampy floodplains on the final stretch near the lakes in low flow periods.
Historically this region seems to have been a prime dairy area with sweet pastures. As always I sought the industry links but that was after I looked for the pioneers around the 1840’s.
This country used to be full of floods. I have an album from a dam builder in the Murrumbidgee catchment showing districts near Yass under water before Burrinjuck . Then I can see in Glimpses of Australia 1897 “an album of photographic gems” floods, dams and weirs everywhere. It says our cemeteries are full of drowned people. “A Banker” shows horses an men swimming through the redgums.
One such weir is on the Goulburn River in a scheme costing over a million pounds then. It was built to irrigate some 775,000 acres in Victoria. Murray Goulburn cheese is still the cheapest on the supermarket shelf. First in best dressed hey.
Peter: My picture book is full of trees and ferns too.
Louis – you’re such fun.
So tell us what isotopic methods, rare earth profiling or perhaps OSL techniques you prefer Louis? Or did you just carry the bucket.
Incidentally what happens to your particles when they get into Lake Argyle? Do you see them later at Wyndham?
Perhaps much of the land clearing erosion impact in the MDB that has exited the paddock is in the channel systems. 150 years of it. What size fractions do you think get into Lake Alexandrina Louis old mate.
See you in 100 posts.
Another red herring from Luke on sediment traps etc. Of course there are lots of locations where sediments could be deposited all up the river system but none compare to Lake Alexandrina. And it is the river mouth that generally defines the scale of sediment loads.
Of course, we can do the same calculations for the river system above the Hume or above the Beardmore but the result is much the same. The wild claims of serious and widespread degradation through erosion problems in the MDB are not borne out by any significant deposition in any of the natural or artificial base levels.
But I am off to the real world for the next three days so hopefully we might see some actual information on volumes of diversion pre 1933.
gavin, the water diversions in the 30’s totaled 3000GL, compared to flow of around 12000 at the mouth. As there were few storages of note (Hume Dam opened 1936) I think water would have been of a seasonal nature with periods of low flow even in average years. The development of irrigation around the lakes could not tolerate salt incursions and riparian landholders liked the fresh water for their animals,so building of the Barrages began in 1935 after years of discussion and droughts.
“storages were put there primarily for irrigators who allow most of it to evaporate”
If you mean via evapotranspiration, then yes by nature most of the water evaporates. If you are questioning application efficiency it is generally around 80%. Some farms on heavily regulated rivers(major storage dams) can just extract straight from the river and put it on crops netting great efficiency, others have to store on farm and have lower efficiency. I wouldn’t call 20% evaporation loss “most”.
Rojo: Thanks for your input again.
In considering the fate of our 10 B or the fate of the MDB for that matter; we cant just focus on one or two users or their efficiencies. I tried to broaden this discussion with input about two major tributaries that don’t get up much on this blog.
We see a lot about crop irrigators versus environmental flows though. That’s why I suggested we look at the mainland dairy industry, what’s left of it at least since I’m all for the survival of small biz. Where it’s located could be an issue as we think about tourism recreation, retirement etc.
Rojo: My point about irrigators in general was they don’t return any water to the river hence it’s all evaporated eventually. None of it reaches the Coorong as it once did.
Yesterday I asked a polly on air about how many times we can recycle our urban bit under a proposed high tech scheme to reuse part of our “environmental flow”. His answer was in thirds.
Back to barrages: At a glance the lakes system is typical coastal formation around deltas impacted recently by fluctuating sea levels. Let’s face it Bass Strait coastlines were about 2 M higher than today not so long ago. The people of Goolwa may need some sand bags, inland pumps etc at the outlet soon.
Gavin,
Please re-read my post carefully. I stand by what I said.
The Murray is today very much an artificial river system. Floods no longer occur or are regulated to the nth degree. When flooding does occur it is not when natural flooding occurred. Water flow within the river is maintained at all times and this water is colder than what would be considered natural.
The barrages were not the result of massive diversions. Please review your history as the massive diversions occurred much later, after the snowy scheme can into effect.
Inflows have recently decreased due to this curernt drought, they are NOT the result of climate cxhange or global warming, indeed no such evidence exists to support your claim.
Historically, in times of low or no flow, due to drought,lake Alexandrina was inundated by the sea and did indeed become brakish. This is a shallow body of water of some 360 sq km. The evaporation rates I suspect would be far greater then that which occurs due to irrigation or other means.
PLease don’t fall into the trap of believing that this is a pristine river system or that it retain some sense of naturalness. It is as artificial as as any other man made structure.
Peter: I certainly “don’t fall into the trap of believing that this is a pristine river system” however it still retains some sense of naturalness everywhere. Only the flows have been wantonly distorted by man made improvements. Believe it or not, even that doesn’t bother me too much.
What bothers me Peter is your insistence there is nothing wrong under the sun.
Today folks we had a report in the Canberra Times on yesterday’s notice from our Chief Minister on radio 666 of the impending debate re recycling. These are the facts:
1) inflows over 6 yrs are down 65%
2) last years fell 87%
3) CSIRO had only predicted a decline of 30% by 2030
http://canberra.yourguide.com.au/detail.asp?class=news&subclass=political&story_id=568797&category=Political
Peter will almost certainly put that down to forest regrowth after the 2003 bushfires.
Since I take an active part in the water debate I will stick to my stuff and Peter is a jolly good bloke for trying hey
Gavin,
Nice try, however since when did you start to believe anything that our politicians tell us?
Gavin I also take an active part in the water debate and whilst I do not doubt your sincerity or the fact that inflows are down I do question the modelling that CSIRO has done suggesting a 30% decline in inflows.
Am I surprised that inflows are down in recent years? No not at all. We’ve been in drought for at least as long as inflows are down. Am I surprised that 2006 recorded its lowest inflows? No as I’ve stated before any regenerating forest has first dibs on the available water, it’s basic plant physiology.
And Gavin I have never insisted that there is nothing wrong under the sun, many of our natural systems have declined or are in decline. I do not, however, ascribe to the “popular” solutions put forward by most green groups and others who believe that its all doom and gloom. I have a great deal of respect for our natural systems and understand that they have the capacity to recover from streses, be they drought, fire or disease. If our forests, grass lands and river systems did not have the adaptive capacity to respond to stresses, natural or human influenced, they would never have evoloved in the first place.
Luke
“So tell us what isotopic methods, rare earth profiling or perhaps OSL techniques you prefer Louis? Or did you just carry the bucket.”
suggests that you also don’t understand the meaning of “non-sequitor”.
You also seem to have no personal experience, or understanding, of fluid transport involving sand-sized (defined on the Wentworth-Udding Scale) particles.
Or are we to assume that your posts here are by soliquies? (pessible spilling irror hear)
The topic was sedimentation and it’s origin Louis. Deductive scientific methods not watching sand grains wash around in some Kimberley creek. Get updated gramps.
gavin,
“Rojo: My point about irrigators in general was they don’t return any water to the river hence it’s all evaporated eventually. None of it reaches the Coorong as it once did.”
The whole point of my post is that the Murray has no “noticeable influence” on the Coorong, effectively meaning the volume of freshwater is irrelevant. The key is maintaining water movement through the mouth, which could be achieved via nature, not mimicry.
Your point about recycling escapes me. 3 thirds is a whole, which third is relevent?
Because the Murrumbidgee flooded in 1897 doesn’t mean it didn’t suffer a few years later in the federation drought. Perhaps flood mitigation is a reason why fewer headstones refer to drowned people these days. How do you put a value on that.
“The topic was sedimentation and it’s origin Louis. Deductive scientific methods not watching sand grains wash around in some Kimberley creek.”
Luke!
Not knowing the mechanism of how the different types of sediments are carried and where, renders any discussion about sediment meaningless.
In this respect Louis’ post was quite appropriate.
Mark.
Shifting sediments is a big topic. This is where we need to understand the history of billabongs and anna branches. Sometimes I comment here on non linear events as we find them in industry, settling sludge or movement as laminar flows.
Natural floods are very different to big dam releases. Anyone who has fished the Goulbourn and studied the Breakaway should know what I’m talking about. Steep eroded treeless banks are hardly natural either. Eildon Weir changed a lot of things. I often recall the fly fisherman’s lament over the “Shannon Rise” loss up in the highlands of Tasmania.
Rojo: We could return 1/3 of Canberra’s treated effluent to town fresh water catchments soon. In an ideal world another 1/3 of the original will go round again, and again but ever decreasing each time. However it’s an increasing small gain in terms of the Murrumbidgee. See my Canberra Times link.
Peter: I bet Rosslyn Beeby would probably say our CSIRO scientists have either been muzzled or watered down in terms of worst case climate reports.
This 10 B of taxpayers dough must be squarely aimed at whole of river fertility long term.
Rojo: This comment should set you thinking and I hope it proves to one or two others how I see opportunities.
In those wildest of years I heard a rumor about a certain brackish pond hidden in the sand dunes of NE Tasmania. I packed the Hillman then trekked in alone with a solid glass rod, lots of line and a choice wattle grub.
Bang! It was on and the water boiled. That black shallow and probably very salty water was full of rainbow. The rest is history but these days most of the salmon are grown in the big briny. The one thing I noticed was the abundance of natural? water weeds. I think this was the site for first fish farm in the country which is surprising if it was.
After googling Waterhouse Lagoons etc. I seemed to have got into sea levels, coastlines and sand dunes long before the terms “RAMSAR” wetlands were invented.
Jennifer: Note how I have never been a greenie when it comes finding trout.
“Close the sea gate and stuff the Coorong with Rainbow and see what happens there”.
Gavin, and Roslyn Beeby is an authority? on what pray tell? She writes for a newspaper that’s all and presents a particular viewpoint.
Peter: We don’t believe in polywaffle, science writers, climate change, AGW and according to Jen’s latest thread, blog posters. Who or what else?
The majority of stuff posted here was written originally by somebody else link after link.
Guess you and me are the only ones talking from experience.
Hi Rojo,
brilliant post. I was at a wetlands conference with a shark fisherman at Berri in late 2000. I got to the Bakery at dawn and the women there told me that in the 1970’s if you did not get a park near the lake by 7am on a good day, like the one when I was there, you would have a walk. The lake was not real bright in 2000 and there was plenty of parking. She also spoke of dolphins in the early 1970’s. Just an annecdote – but I do have a reference for fur seals being taken from Broken Creek, a tributary of the Golburn near Shepperton in the 1850/60’s.
Removing the Barrages would restore a large part of the fish production of one of (if not the) largest estuarine systems in Australia (including the Coorong).
The fresh and saltwater ‘fight’ each other along a wedge that moves upstream in low flow times and downstream in higher flows.
If freshwater could be harvested from the surface of the river (technology?) maybe the wier at Wellington would be unnecessary.
Installing overflow for release for wiers the release from the ‘bottom’, with decent fish (dolphin and seal?)ladders would make difference too, giving salt a chance of ‘staying low’ and contaminents time be made into sediment.
Again thanks Rojo, I never thought I would here it said. There are approx. 10,000 floogates from the southeast to Queensland that could do with removing or regulating to allow toidal flow again for fish production too – another story for another day.
Bob, I think you are right in saying before the Barrages that where the salt and freswater met moved according to river flow. Upstream during drought and out to sea during floods.
Release from the “bottom” of weirs would be a problem for fish passage as velocity will be high. Considerable money is being spent on fishways on existing weirs.
Whilst I think your estimate of 10000 weirs a liitle high(3000 in all of NSW) it should be noted that many are essential to provide water storage for towns. Some 40% of the Barwon/Darlings length is weir pool water for this reason skewing natural vs current flow measurements along with the Menindee lakes.
I have just joined this blog, my first blog. I live at KOM and have done so since arrival after canoeing the Darling and Murray rivers on the flood of 1983.
It took three years.
I don’t buy newspapers but rely on the web for my information.
I understood that the proposal to build a weir at Wellington would always involve the removal of the barrages, am I wrong?
Commercial fishing in Alexandrina during the 1900-1920 was for saltwater fish. The barrages stopped this fishing industry dead?
I trust someone can confirm or deny this info.
fluff
Frank, as far as I am aware there is no formal plan to remove the barrages. The proposed weir at Wellington is to protect Adelaides water supply.
I trust someone knows what their doing?
The money is for the Murray, not Adelaide water. If there is no removal of the Barrages it’s goodbye Coorong. I read it’s already 2&1/2 saltier than the sea. This is exactly why the money needs to be administered by an independent authority, not pollies. There is little lost from an economic point of view if irrigation were to cease, that is no pumping from Alexandrina, and compensation is paid.
I’ve believed for a long time Alexandrina was once salt, at least brackish. Old timers tell me thats how it was. River flow had limited influence on the water condition, just colouring with sediment.
I look forward to sea rise from warming, re the Coorong. Dreadful for Pacific islands and Bangladesh of course.
fluff
frank, people under estimate the value of irrigation. Through irrigation 50% of agricultural profit is derived from 0.5% of the land area in Australia. And while farm gate price constitutes only a few percent of GDP the flow on effect is much greater, particularly for rural populations.
More importantly ag exports make up some 30% of total export value which I feel is a better measure of worth.
Obviously Lake irrigators are only a part of the whole scene but, to their communities, of vital importance.
I don’t share your view about sea rises. Little human misery is occuring as a result of hypersalinity, a lot of pain will result from massive people relocation. And to where?
Rojo: the sea was in and it seems the sea will come in again. your problems will be resolved soon by all of the above inc AGW starting about 200 yrs back.
Mussels on the dairy farms!
One of the original justifications for the barrages was to provide a back up for Adelaide’s water but it remained far too brackish. So now we get another weir for the sake of a city that is too damned tight to build a desalination plant?
If it is OK for Sydney and the Gold Coast, why the hell is it not OK for Adelaide?
Interesting that total diversions in the 1930’s were only 3000Gl. Is anyone seriously suggesting that this is sufficient to alter tidal patterns in a 360km2 estuary?
Lets look at the numbers. 360km2 is 36,000 hectares and even by todays modest 0.7 metre tidal movement in that estuary will involve the movement of 252,000 megalitres four times each day. Meanwhile, our claimed missing 3,000Gl, if averaged over the whole year, will amount to only 8,220 megalitres a day. Half of this amount (4,110Ml) will impact on each high tide.
This will mean that the area of formerly fresh water that is replaced by sea water on each high tide will be 4110/7 = 587 hectares. This is only 1.6% of the lakes area.
Clearly, the anecdotes of changes in tidal movement could only have been based on a very limited view of the whole system and most likely from a particular point where the river meets the lake.
Any other result, such as by calculating the volume of flood surges etc, can only be derived at the expense of even less significant flows during the rest of the year.
It is also worth pointing out that the mooted 1,500Gl of additional fresh water from buy-backs etc would only deliver 0.8 of 1% of the daily flushing that natural tidal movement would supply.
gavin , I don’t really have any problems either way. I don’t depend on the Coorong or it’s health, but I’d rather see it healthy. If the govt need my water to do that, they assure me I’ll be compensated.
it’s the rural towns who will miss out through water buybacks, less turnover,less customers less employment. If water needs to be bought back it needs to be for sound scientific reasons.I just don’t happen to think attempting to poorly mimic nature with fresh water flow is a worthy reason.
Rojo: If I can, you can hey.
They quietly offered me a package a while back when I got in the way so I snapped it, small as it was before the bloke next to me had a chance.
Retirement from magpie squabble can be bliss I thought. More time to do the other things too like bloggin.
Many old industries I knew got the wind up, small farming, fishing, dairying, sawmills, telecommunications in the bush too. That’s the progress we had to have
Most of us moved on from what we thought was a lifetime career.
A 20% drop in agricultural production shaved 0.7% of the annual growth of 2.8% last year’06. The MDB contributes 70% of agricultural output.
What would happen to interest rates and property booms if we reduce output by 80%.
SA’s 1850 gig allocation was based on how much water was required to allow paddlesteamers to operate up the Murray.The barrages were put there to back the water up for the uncompetitive paddleboats.
The alleged “science” that the Wentworth group and others use to recommend the addition of 3000 gigs of water to save the once mighty Murray turns a blind eye to the waste of water estimated by some to be inexcess of 1000gigs in evaporation in SA lakes.
Where do Mike Young and Peter Cullen stand on these turpid lakes in SA?
More water would pass through Lake Alexandrina in one day if those antiquated barrages were removed than reducing extraction by 3000gigs.
Nobody wants Port Phillip Bay to be fresh water though I would bet large amounts of money on the people of Melbourne wanting some of the fresh water that is wasted uslessly in the SA lakes
The irony in all this is that it is the lower Coorong that has developed the salinity levels that exceed that of the sea (35,000ppm) not the part near the barrages.
Now a practical person with an eye to his statutory obligations to use the most effective and economical method of fixing the problem would not look 600 KM away up stream to see which farmers he would like to put out of business through confiscation of his water.
No, an even mildly thoughtful fellow would note that there is only a short body of sand between the unhealthy excessive saline water and the abundant waters of the southern ocean. He would recognise that mankind invented “the pipe” some 3000 years ago at least. And he would note that one of the easiest mediums to dig in is sand.
And he would put a few pipes under the sand bank so the tide can once again flush the stagnant waters and restore that ecosystem to good health.
Who knows, they could even install some turbines so the tidal movement could generate carbon free electricity for the grid in a win, win, win triple bottom line that might even turn a dollar profit as well as an ecological profit.
But don’t expect anything like that from the unspeakably incompetent green luddite scum that deliver 99% of the noise to the policy process.
gavin, I can only guess why “they” would try to get you out of the way.
Yes Let the sea water back in..
All the people yelping about the lake to stay fresh water are only worried about themselves. Return Australia’s largest estuary back the way it was before the barrage.
I also have a theory on why Adelaide southern beaches are disappearing. Beach sands come from the Murray river. In floods the sand is pushed through the mouth out to sea. Then the currents take the sands thru Backstairs Passage and depoist them on the southern beaches.Slowly making there way to Port Wakefield. Due to lake of floods in the last 50 years The sand movement has been affected.
Does anyone have any ideas on this subject.
Quote Graeme Pyle, Mar 2007: “And he would put a few pipes under the sand bank so the tide can once again flush the stagnant waters and restore that ecosystem to good health.”
I have sailed the lower Coorong a bit in the past and I seem to remember what looked like a large sluice gate on theseaward dune side in the vicinity of the mouth of Saltwater creek. I saw this on my last trip in 2004 I think, but did not go ashore to examine it. Sadly, since then the salt level and lack of water has stopped my expeditions to a favoured place.
Quote Graeme Pyle, Mar 2007: “And he would put a few pipes under the sand bank so the tide can once again flush the stagnant waters and restore that ecosystem to good health.”
I have sailed the lower Coorong a bit in the past and I seem to remember what looked like a large sluice gate on theseaward dune side in the vicinity of the mouth of Saltwater creek. I saw this on my last trip in 2004 I think, but did not go ashore to examine it. Sadly, since then the salt level and lack of water has stopped my expeditions to a favoured place.