THERE has been severe flooding along parts of the east coast of Australia with the towns of Grafton and Lismore evacuated over the weekend. Grafton is towards the bottom of the mighty Clarence River which is completely unregulated. I can’t find a reliable estimate for the amount of water discharged on average or during flood events. It drains an area of 23-thousand square kilometres.
It doesn’t matter what time of year you drive through this region, known as the Northern Rivers District, it is always green and the wide Clarence is always brimming with water.
In Australia we repeat the mantra that this is the driest inhabited continent on earth but, according to the World Resource Institute, we have 51,000 litres of available water per capita per day, this is one of the highest in the world, and well ahead of countries such as the United Kingdom with only 3,000 litres per capita per day.
We have chosen not to dam most of our big rivers, only developing significant infrastructure in the far south – in the dry Murray Darling Basin.
There are those who, in the past, have wanted rivers like the Clarence dammed and turned inwards to supplement irrigation in the interior – in the Murray Darling Basin.
While it has been claimed damming the river would destroy its environment, such claims are based on little more than value-laden opinion. There would be environmental benefits from damming in particular from a flood mitigation perspective. Indeed the regular flooding of urban and industrial centres can’t be good for downstream water quality.
I’m neither for or against the damming of the Clarence, but I wish politicians and the media would at least acknowledge that the recent flooding is an inevitable consequence of development on a flood plain along a mighty river that the locals do not want tamed.
While there has been flooding in parts of eastern Austraslia, much of inland south eastern Australia is still in drought. The lower reaches of the Murray River are still drying up and a new group was formed recently to lobby for the barrages, built to keep the lower reaches of this river fresh, to be opened to let the Southern Ocean back in to inundate the area.
It seems that here in Australia we are very much supportive of the status quo. If a structure has been in place for a long time, for example the barrages at the bottom of the Murray River, we are loathed to dismantle them. If a structure has never been built, for example flood mitigation for the Clarence River we are loathed to consider it. I am not sure we were always such a timid, recalcitrant and unwilling lot.
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Notes and Links
Recent rainfall not so rare
By ABC weather expert Graham Creed
http://www.abc.net.au/news/stories/2009/05/23/2578931.htm
Clarence River Stories
http://www.abc.net.au/rural/features/clarenceriver/
Lower Lakes Crisis
http://www.lakesneedwater.org
Saving the Coorong by restoring its native state
http://www.onlineopinion.com.au/view.asp?article=7762
The photograph of the dairy cow in the paddock was taken west of Bellinger in the Clarence or Bellinger catchment of the Northern Rivers District in January 2007 by Jennifer Marohasy.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
Jennifer, I did take your take on recent events seriously to the point I tried to read it carefully and discover what your claims were on about it. I put them in your category of people who are anti-damning rivers. “such claims are based on little more than value-laden opinion”. Then your clincher to finish –
“I am not sure we were always such a timid, recalcitrant and unwilling lot.”.
If you want to make value laden opinions on your convenient links between rainfall, flood frequencies, flood plain management, water resource economics, behavioural psychology including risk management, you cant shoot from the hip at targets that were there before the weekend. Pls get some facts together first. Then push your irrigation lobby.
Residential or industrial development on alluvial flats subject to frequent flooding should operate under the warning Caveat Emptor.
No sympathy for those who buy land in flood prone areas.
Stupid is as stupid does, as they say,
Bazza,
” Pls get some facts together first. Then push your irrigation lobby.”
Please get YOUR facts together. How does removing the barrages in the Murray help the irrigation lobbies?
Please reread her last paragraph.
“we have 51,000 litres of available water per capita per day, this is one of the highest in the world, and well ahead of countries such as the United Kingdom with only 3,000 litres per capita per day. ”
Yeah, but where are those 51,000 litres per capita located wrt to the population per head? Don’t forget in the UK 30 million people are located in a 50 -70 mile radius of Westminster so while they have a 3,000 litre lot they are located a couple of thousand k’s closer to the taps source than the average Australian.
“While it has been claimed damming the river would destroy its environment, such claims are based on little more than value-laden opinion” Evidence please.
I want to know, why live on a flood plain without raised infrastructure rather than damming the river.
In reality, isn’t your wanting to dam things driven by ‘values’ as well?
The statement that “In Australia we repeat the mantra that this is the driest inhabited continent on earth but, according to the World Resource Institute, we have 51,000 litres of available water per capita per day, this is one of the highest in the world, and well ahead of countries such as the United Kingdom with only 3,000 litres per capita per day. ” says it all. A natural disaster should been viewed as the retribution for what we have sown. If we stop killing cows, kangaroos, chickens, etc. for their flesh, we would reduce climate change by at least 70%. The livestock industry is the primary source of GHGs and the meat industry is the most inefficient product in terms of resource requirements (water, grains, energy), deforestation and land requirements. Cutting back on our meat consumption is the first step towards a lasting peaceful solution to our climate change problems. We keep taking in from Mother Earth but giving back nothing.
http://www.alternet.org/environment/140059/our_appetite_for_animals_is_taking_us_toward_apolcalypse/
http://www.myyogaonline.com/healthy_living_212_Factory_Farming-Cultivating_Destruction.html
http://www.rkpachauri.org/speech.php
I agree with Louis.
Here in the US, if a person’s house is flooded out when the local river overflows, our government is likely to say, “Poor baby! Here’s some money for you to build a new one.” This may be a reasonable approach for farmers, who can’t reasonably be expected to commute from houses on higher ground to their farms every day. But most people who live on floodplains should shoulder the risk.
People who choose to live in disaster-prone areas should be required to purchase commercial insurance to cover the full replacement costs of their houses. And there should be zero subsidies from Uncle Sam. Market forces will prod people into being more prudent about where they choose to live.
How do Australians feel about that?
Larry,
In many flood areas the risk is so high you can’t actually get flood insurance!
Jeremy,
Of course its about values – my values versus yours.
Bazza,
It is recalcitrant to not open the barrages even though it will disadvantage the irrigators and it is unwise to not do something about the regular flooding of places like Grafton and Lismore even if it might advantaged the irrigators.
PS Larry I lived in a flood prone suburb of Brisbane until recently (18 months ago), I couldn’t get flood insurance, but it was very convenient and there were lovely walks near the river. I was going to move as soon as my daughter finished school, but I waited an extra year until she moved to Sydney. My concern was less getting flooded, as I figures the house could cope with that, but that property values would dive as soon as there was another big flood. The area last went under water in 1974. Since then a large dam has been built and the predicted maximum flood height is now 2 metres – it went under 4 metres in 1974.
People don’t seem to realise that Casino, Lismore, Grafton and all the towns downstream are only 2m above sea level. Lismore was built on the Wilson river because the ships would travel up the Richmond and berth there. The whole area is a huge flood plain.
Lismore’s levy banks are only a recent addition and flooding has been part of it’s history
http://www.lismore.nsw.gov.au/content/uploads/Historical_Flood_Graph_June_2008.pdf
I went and checked the Clarence at Tabulam and the river was up – but no where near the level it’s been in the past where the bridge has been photographed only a few feet above the water level. My local flooding wasn’t as bad as last year according to the locals.
Dam the rivers!
For the money the Rudd government has pissed up the wall already we could have committed to build a lot of water infrastructure and moved the water from where it occurs to where the people are.
As for “We have chosen not to dam most of our big rivers” – gee are we sure – check out the list –
http://en.wikipedia.org/wiki/List_of_reservoirs_and_dams_in_Australia
I think Peter Andrews has an interesting solution – slow the rivers down
http://www.nsfarming.com/index.html
Jennifer,
The Clarence river delivers an average annual flow of 4 million megalitres to the sea. However in flood years like this it is often up to 12 million megs.
The Clarence could easily support a Snowy like Scheme with greater generation capacity of clean power.
To Jeremy C above,
It is actually a fact that the majority of the Australian population do live where most of the run-off occurs. On the coastal strip from Adelaide to Cairns.
I’m too busy to respond in detail now but suggest you read my paper “Water in Australia” on this site.
The facts there support Jennifers figures above.
Pikey.
As a student who lived in the worst house in the worst street in Lismore during the 1974 flood, (it went clean over the rooftop) I can confirm that Lismore CBD is much more than 2m above sea level, more like 6 or 7m.
Jennifer said the ‘locals’ don’t want to dam the Clarence but one is moved to ask, which locals? It seems that every Australian for decades has had an opinion on whether the waters of the Clarence should or should not be diverted inland but few have actually bothered to ask the farmers who own the land in the catchment that supplies the runoff.
The entire soil moisture deficit in the Richmond/ Clarence region is only 4 megalitres a year while the deficit in the west is as high as 16 megalitres/ha. It follows that water used to irrigate crops and pasture within the region will guarantee full moisture profiles for up to 4 times the area that it would in the west.
And these surveys of opinion on whether to dam a river always focus on the use of a single megadam rather than the slightly less efficient but also lower impact option of numerous smaller dams. There is already a wide network of farm dams in the Clarence catchment but there is clearly considerable scope for a lot more.
If the public were properly informed as to the full range of storage options and the resulting spread of the diverse habitats they provide then there is little doubt that they would support them. But for the moment, farmers in NSW are only guaranteed a minimum storage entitlement which so low as to be laughable. It was presented as some sort of ‘guarantee’ but in reality the whole scam was a serious theft of property rights.
Generally, the system assumes that runoff will be 10% of mean annual rainfall and the as-of-right storage entitlement is only 10% of this figure. That is, only 1% of total rainfall can be captured as part of the as-of-right entitlement.
This seems fair enough for your average urban moron until one considers that the change from forested land to pasture can boost runoff to 30% of total rainfall and it can go even higher on those parts of the pasture rotation that have lower fodder levels. Conversely, the regrowth of forest on pasture land, as is very prevalent in the NSW North Coast, can reduce runoff by a similar order. Even a standard partial harvest of trees, where every second tree is cut so the remaining trees can grow larger, can improve runoff volumes for up to 20 years.
So the current flows in these rivers are substantially greater than they were in pre-settlement times but the green movement and their captured bimbocrats continue to pretend that any reduction in current flows would be “bad” for the envirnoment. This is in direct contradiction of the fact that any change from the pre-settlement range of variation in flows, be it increase or decrease, is a departure from “nature” that can have adverse impacts on the species that have evolved in that pre-settlement ecosystem.
And it is these species, and their original range of variation in habitat, that must form the basis of any environmental duty of care. To use the substantially increased river flows as the determinant of environmental duty of care is both intellectually flawed and a gross injustice to the landowners who have produced the surplus flows. Indeed, given that much of these catchments were compulsorily cleared on pain of forfeiture of land title, then the states confiscation of the resulting increased water yield is very sinister indeed.
The means to determine exactly what the original flows were under the historical range of rainfall events has been around for more than two decades. And if the farmers who have created the increased flows are given their rightful ownership of the portion of water flows that have been produced by their lawful improvements then they would be able to capture more of it on their land. And they could then sell surpluses to downstream irrigators and urban centres and those same downstream users would get their flood mitigation services for free.
It is classic free market ecology of the best kind that requires no major public investments, that delivers a widely dispersed set of environmental and economic benefits and avoids the diseconomies and adverse impacts of major storage facilities. If only the ignorant green tightarses could get their tiny brains around the issues.
We have 51,000 liters of available water per capita per day; this is one of the highest in the world, and well ahead of countries such as the United Kingdom with only 3,000 liters per capita per day. ”
But if both of out dominant governments have their way, they will continue to increase the population here as fast as they can to bring us into line with countries like the UK.
Also it is sticking your neck out to live in any area where there is the potential for natural disasters to occur, see Queensland for cyclones, Victoria for bushfires.
Of course one of the pointers towards that from terrible lie” global warming” is extremes weather events. Now are you sure you are on the right track?
Dams by the way eventually always silt up and compound the problem as well as losing immense amounts of water through evaporation.
Ahhh VilHQ. I seem to recall, Ian , that that house was the 3rd house in Lismore to go under, and consequently the 3rd last to emerge. Of particular interest was the progession of snails etc working their way up the walls and lizards moving inside as the water rose.
Where are you Oodnadatta?
Don’t ever forget Ian that green tightarses are tight with their $ contribution but oh so loose with general revenue.
“your average urban moron” – so why are you here then ? Trying to reduce the statistic downwards even further ? You’re out-voted droopy draws – get used to it – so get back in line or move to Bolivia (Hill).
Actually, neither Grafton nor Casino are as low as 2m above sea level. The river surface when viewed from the bridges in each town are far below and those bridges are only slightly above the level of the towns.
Another substanceless rant from the boy wonder. What a waste of space.
ok – to be precise Lismore is 9m, Grafton 8m and Casino is 25m – point being the land around is very flat and it therefore takes a while for the water to receed.
Of course with all that Mottsa endorsed tree clearing in the catchment – there’s probably a good case for a class action against the tree clearers for extra peak runoff and MUCH greater flood heights.
– can have it both ways, but that’s what your gain capitalising, loss socialising faux urban property rights crowd are really on about…. tsk tsk tsk (as well as loitering around shopping malls).
The Timbarra river that flows into the Clarence would be easy to dam. I remember being impressed with how small the dam that flooded lake Argyle actually was, a similar situation occurs with the Timbarra as it narrows to many gorges and it would create a huge lake behind.
Fortunately it is full of gold so it’s not likely to happen 🙂
Northern NSW is some of the best country in Australia and, sadly, fast heading for multi-city development and dams in this area now make so much sense.
However it wont happen and when it is too late we will get these wonderful desal plants that cost a dollar a litre for brackish water.
You would think that the dumb warmers would at least realise that big fresh water storage is reducing ocean acidification.
“Fortunately it is full of gold so it’s not likely to happen :)”
janama, and I’ve got the dust to prove it.
The land around the Clarence has been f**ked over. It’s just had endless super added, cattle removed, and nothing put back. That’s according to an alod lady I spoke to from one of the original stations around here who had just sold out to Great Southern. Land prices have been totally over-inflated by the Southern Plantation mob so even the farmers who are still hanging in can’t expand as their neighbours leave the land to retirement homes and the kids move onto the cities.
It’s actually an agricultural boom area waiting to happen. New land regeneration techniques (biodynamics etc) just need to be employed.
one of the good stories I heard about the oil price escalation recently was the story of farmers creating their own fertilisers. It can be done.
Well spanglers – that’s becoz dumb denialists don’t realise that dams produce sheetloads of AGW tweaking methane for centuries (whether you remove the trees or not).
And shhhh Janama – don’t tell Motty – he knows that past land management practices are always beneficial.
that should be “an old lady”….sorry
what would he know about land management practices in Upper Main Arm?
Ian Mott, Bimbocrats, love it !!! 😉
As usual you have some very good solutions for the present problems but I fear that the weasel worders have won the political battle and you forthrightness will almost guantee the you will not be heard. But there is some consolation in knowing that you are right.
“that’s becoz dumb denialists don’t realise that dams produce sheetloads of AGW tweaking methane for centuries (whether you remove the trees or not).”
Luke, do you really believe that dumb warmaholic crap?
Trees don’t decay underwater and other biomass in dams is no different to what ends up in any other still waterway, including the ocean.
Ever heard of swamp gas?
All wetlands including dams, peat bogs, mud flats, marshes, anywhere organic matter decays, produces methane.
On the plus side [GHG offsets] dams produce big amounts of energy, their catchments preserve for ever eco zones from development, provide permanent agricultural areas close to cities reducing freight, likewise with rec areas, open space amenity AND SHEETLOADS of low cost WATER!
http://www.realclimate.org/index.php/archives/2006/10/rasslin-swamp-gas/
‘Guarantee that’ — tch tch
That link, I forgot to mention, was from your mates at RC and with a quick read I couldn’t see too much about dams.
Decidedly moronic spanglers – “Ever heard of swamp gas?
All wetlands including dams, peat bogs, mud flats, marshes, anywhere organic matter decays, produces methane.”
errrr – yes goober – that’s what we are talking about!! You’ve cracked it old son. Brilliant.
Ever heard of shit spanglers – well mate this is new “extra” shit. err methane.
Trees will produce it over centuries. That’s centuries mate. We’ll send your great great grand kids the bill.
Not to mention flooding vast areas that somebody owns (so much for property rights), changing flow regimes abruptly, creating migration barriers. And like with all Aussie irrigation systems – unstable salinisation will be around the corner somewhere.
Then my tax dollars will have to bail out the gain capitalising and loss socialising ag sector again.
Hey Luke,
How about acquiring some practical knowledge and truth on this subject before littering the site with such unsubstantiated tripe.
It’s more likely the ag sector is subsidising your lack of work.
Or is hounding this site with nonsence, what you are payed to do?
Pikey.
Oh Pikey – you guys are good at capitalising gains and socialising losses. It’s your stock in trade mate. And what – we’re going to listen to some random bozo like you with plans to divert every river in the Commonwealth on the basis of your megalomanical fantasies. Didn’t get enough toy trains as a kid ?
Thanks, Julian. But sense will eventually sink in but, like the folks in North Korea, the prevailing bull$hit will need to run its course. The green destiny is to stuff things up so badly that even the metromorons will stop believing them.
And speaking of morons, if Luke was even 5% of the way up the learning curve he would know that the area of native forest on the NSW North Coast has increased by more than 1 million hectares since the 1950s. And that is net of all clearing during that time. We have the full sequence of 1942 and 1953 aerial photos for Byron Shire and I have seen the ones for north of Lismore and out around Casino. The story in areas further south is exactly the same, according to the old timers who were actually there at the time.
And if you had ever been to Toolond, (upper main arm) Janama, you would recognise how much we know about land management practices.
Indeed, if Luke had the faintest idea how to read the history of a landscape by observing the size and shape of trees, stumps and even fence posts on it today he would recognise the substantial recovery of forest cover that has taken place. But instead, he has a head full of the leftist departmental bull$hit that claims that farmers only produce environmental costs while government neglect and incompetence only ever produces environmental benefits.
But that of course, is standard MO for the sad collection of landless, treeless departmental drones who spend all their time deluding themselves that they would make a competent land manager’s armpit. Tell that to all those landowners who got suckered into letting QDPIF and NSWSF cover perfectly good land with “miracle” plantations that are lucky to show even half the growth rates they were claiming and leaving them with a bill for stump removal that is close to the full value of the land itself. I hear they could use a good laugh.
“Trust me, I’m from the government, and I’m here to make you lots of money and save the planet”. Yeah, right, and how much for a bridge?
Golly it’s confusing isn’t it – so yesterday Motty was telling us all that land clearing had increased water yields (while not offering to shell out for the flood damage thus caused) – but today the vegetation has suddenly grown back. And this is going on everywhere!?
And the poor poor farmers (who he had been telling us knew what they were doing) have suddenly been duped into planting a whole bunch of trees they didn’t want.
Uh-huh. OK. That all makes sense doesn’t it?? No inconsistencies in the arguments folks?
LOL !
I have been to upper main arm Motty – many times as i used to duck through there to get to Uki and I’ve spent many a Moon Dance in the hall. All the regrowth you refer to is just Camphor Laurel and Lantana gone crazy! I know – I’ve lived in the area for over 30 years mate.
The regrowth around Casino you refer to is also just regrowth baby gum trees because they ripped out EVERY millable tree in the area – the Mill at Drake, CLOSED out of trees! the mill at Urbenville is still going just! – I see the trucks carrying the logs, babies – any log close to 300mm ends up at Hurfords at Casino for the Sydney hardwood floors.
Don’t try and tell me there’s been any forest management around here – it’s a damn joke!
fortunately the Yabbra state forest still exists and it’s stunning 🙂
http://users.tpg.com.au/johnsay1/Stuff/yabbra_1.jpg
There are no inconsistencies in you singular comprehension deficit, Luke.
Could someone carefully explain to this pathetic departmental boofhead that the total area of the NSW Nth Coast is 5 to 6 million hectares and therefore a million hectares of regrowth forest on previously cleared land does not mean that the entire region has been fully reforested. Farmers in this one region have regenerated as much as half the national plantation area, with none of the tax perks and none of the departmental posturing, and far better habitat to boot.
And luckily for farmers in that region and SEQ, only a small portion of them were gullible enough to enter into any sort of partnership with government spivs. But Luke just keeps on with the departmental “big lie” that farmers are bad land managers while government tossers, funded by tax cheats and corporate shonks, are planet saviours. Note how he didn’t dispute the fact of more than 1 million hectares of regenerated native forest? Thats because he couldn’t. All he did was sow some fake confusion, a skill that is highly developed amongst the spivocrats. Onyabike, punk.
Luke, Did you read that RC link? No mention of dams as a methane producer. That’s because they are out-produced by shallow wetlands and their construction often floods these same wetlands with a likely net methane benefit.
Other human development is also removing wetlands in huge amounts for more methane reduction.
As for flooding other peoples property, these people get compensated and are often allowed to remain on smaller, more attractive, waterfront property.
And if you’re crying about your dollars, desal is ripping you off 10:1 compared with dams.
I’ve just spent a few days camped at Wivenhoe Dam since the recent rains and with this huge dam filling, the water’s edge is grassy and littered with all sorts of birds, waders, raptors, darters, cormorants, pelicans, by the hundred, possibly thousand attesting to its marine life.
The resumed farming country still has rural use and there would be a couple of hundred kilometers of beautiful uninhabited shoreline that can be explored by kayak or sail [banned to power boats but they fish with electric motors that can’t travel far].
As well as all the other dam benefits, Wivenhoe provides substantial flood mitigation for Brisbane as demonstrated in the last few days.
It has just now saved people a lot of heartache and a lot of money in so many ways and will keep doing it for a long time to come.
Try googling spanglers – perhaps a single link isn’t that revealing. Emissions can be greater than the hydro benefits. Big numbers.
You gotta hand it to Mottsa – the old shell game – which thimble are the numbers under – round and round it goes – a nip here and a tuck there – and he had the numbers up his sleeve all along. Big become small and small becomes big. Doesn’t wash anymore matey – the old ram raid tactics have been long woken up to.
And now “it’s only a small proportion” Woo hoo.
Tell us waddler – why do need to spend all those NHT type funds – give it to me instead.
Game over.
“Emissions can be greater than the hydro benefits. Big numbers.”
Nothing quantified, just a lot of ranting like you always get about dams. So give me some numbers if you’ve got them.
Common sense tells you that swamps and bogs that have organic matter continuously growing thickly across the surface will produce much more methane than deep water in a dam where, relatve to water capacity, there is very little organic matter for any length of time.
And anyway, so effing what! this is an essential part of nature, the primordial slime and all that; y’know, where we all came from and is still teeming with life.
We need more of it, not less.
A desal plant ends up a non-functioning rust stack in no time, with nothing to show for your billions.
Love to post a reply but Jen’s blog dog eats the answer.
Try googling methane dams greenhouse in Google Scholar
And then google normal for : greenhouse dams methane power source ens-wire Read the ens-wire article.
And google normal for : 4% of global warming due to dams
Then you have spent 30 years with your head in a paper bag, Janama. Toolond (Upper Main Arm) has very little Camphor Laurel because it does not compete well with established Eucs. The Camphors are mostly on road sides and even then they have not extended far into Toolond which begins after the school. The only significant Camphor stands are much closer to town at Red Hill/Blindmouth and Settlement Road.
Both my Grandparents were first selectors, one at the top of Huonbrook (the Oscar of Oscar’s Road) and the other in Toolond (at Mott’s Road) and my mother’s side of the family goes back to the first permanent settler in the district in 1882. I helped plant the flooded gums opposite Narada as a 4 year old in 1959 and, as I mentioned above, I have the detailed aerial photos of the entire area from Huonbrook to Burringbah going right back to 1942. And I routinely walked and jogged the entire length of main arm road all through the 60’s and 70’s.
And you have the gall to claim that your late night stoned visits to the Moondance and the odd daytrip to Uki give you a keen grasp of the situation on the ground there. There must have been some very bright full moons. I suspect you might be a few mushies short of an omlette, old mate.
“It doesn’t matter what time of year you drive through this region, known as the Northern Rivers District, it is always green and the wide Clarence is always brimming with water.”
Easy to see that you have never given serious thought to the issue.
http://aclarencevalleyprotest.blogspot.com/ however has done its homework.
“Abstract By means of a theoretical model, bootstrap resampling and data provided by the International Commission On Large Dams (ICOLD (2003) World register of dams. http://www.icold-cigb.org) we found that global large dams might annually release about 104 ± 7.2 Tg CH4 to the atmosphere through reservoir surfaces, turbines and spillways. Engineering technologies can be implemented to avoid these emissions, and to recover the non-emitted CH4 for power generation.”
Luke, this is the “4%” you’re talking about and it’s highly assumptive and fixable as well.
Clarencegirl,
The Clarence is probably the second biggest producer of fresh water in Australia and floods the ever increasing pop regularly.
If we get back to some recent past cycles, this increasing population is in for ever increasing grief.
Have you given serious thought to the issue? Or are you alright J?
Sorry, that first para should include, “on the east coast of Australia”.
Spangled Drongo,
Yes, I have given it very serious thought and as one of those living in a low-lying area of the Clarence Valley I’m not alright Jack.
However, the Clarence River system has a highly variable flow dependant on its major freshwater tributaries.
In early 2007 an adult could have walked across parts of the Upper Clarence without getting his/her feet wet.
Much of its alleged freshwater volume is illusory as the river is salt for about 1/3 of its length.
The health of the Lower Clarence estuary system and fish breeding/feeding habitat is dependant of the existing level of freshwater flows coming down the river.
So is the multi-million dollar fishing industry which does as much (if not more) as any other primary industry in keeping Valley communities going.
Studies have piled up over the years showing that another dam on the Clarence River system would be a dam too many.
As for supplying the Murray-Darling system with water from the Clarence – even the Murray
Darling Basin Commission has said that any water would dissipate long before in got to where it was most needed.
Also, if one looks closely at recent proposals for Clarence river water diversion, it is clear that
it is not intended for inland river systems but for the mining and energy industries across the Great Dividing Range as well as irrigators close to the NSW-Queensland border.
The call to dam the Clarence is an economically and environmentally dangerous con.
Clarence valley water should be used to the benefit of clarence valley users. If there is not enough water somewhere else than the users should go to where the water is.
An extra dam would play a major role in reducing sediment flows in the lower reaches. And there is no reason why the capture of the destructive half of major flood events should lead to any adverse impact on fisheries and habitat in the lower reaches. The benefit provided by a flood surge is delivered on the first day of the flush, not the third or fourth.
It was pleasing to see that you think Australians like to preserve the status quo. Perhaps that is the only thing stopping us from making more monumental stuff ups.
You have no idea what a dam will do on the Clarence, none whatsoever. Neither do I. But, I suspect that the floods are extremely important. I do know that there are fish in The Great Sandy Strait that only spawn when the water is fresh ie in a major flood. I do know that flood mitigation works near Grafton have produced water that is very acidic. I certainly know there is a lot more to a river than meets the eye, and there are unimaginable connections between it and life that depends on it. That is, connections that are unimaginable until we stuff it up and say, “What the…”
With over 35 years as a civil engineer and 5000km observing rivers and landuse at walking pace I feel qualified enough to say that our arrogance has caused us major problems in the past and it still does. It is time to be humble, to work with nature, not to think we can control it.
If we control the floods how do we replenish the land? Currently almost every farm, unless certified organic, operates on what they call “inputs”. These come from oil and natural gas, energy stored for millennia and now being released. But from about now they will go into decline. How then do we eat unless we work with nature and replenish land the way it was always done until we turned up?
We have a very, very long way to go in our understanding of what a river really is and what it means to us.
“Studies have piled up over the years showing that another dam on the Clarence River system would be a dam too many.”
clarencegirl, have you considered the Gold Coast without the Hinze Dam?
Instead of a: large open space ecozone that links up with other ecozones, provider of flood mitigation, agriculture, rec area and lots of low cost, quality fresh water, there would be another 10 suburbs and none of the above.
The development will surely come, don’t kid yourself, and the outcome will be more and more desal plants because they’re politically digestible but they’re a bigger disaster than dams ever will be.
Information on Clarence floods and flows at Grafton can be had via the Clarence Valley Council website. The highest recorded floods-not necessarily most voluminous-occurred in 1887 and 1890,with 1893 also very big. The 2001 flood reached 7.7m with a lower peak flow than others that reached lower heights on the gauge-perhaps an indication of the state of levees,tides and onshore winds at the time.
The Clarence is not entirely unregulated; the Nymboida Weir draws water for modest hydro power use,and now to supply extra off-river domestic water storage of 30GL at Shannon Creek for distribution to Grafton and Coffs Harbour. Of course ,this has no flood mitigation value.. Proposals to divert basin waters over the divide were ill-costed and crudely researched, mainly of value to populists and pollies. The latest proposal involved damming the Clarence above Tabulam and piping water north over the Macpherson Range to the Logan catchment,suggested at the height of the SE Qld drought. This went down very well with the locals,who pointed out that you could step across the river at the dam site at the time,and this was platypus and bass heaven. While that drought has receded, Queenslanders also discovered that urban water conservation wasn’t as painful as they feared. This proposal has only marginal flood mitigation value,as its catchment is only about 10% of the total Clarence catchment,and is one of the less well-watered 10%s,to boot. However,it can’t be ruled out over the next half century.
Development on the flood-plain below Grafton is governed by management plans which have a pretty good handle on flood heights and recurrence.
The ” wide Clarence is always brimming ” because it is indeed tidal to upstream of Grafton. A dam on the river to intercept sediment is a vacuous idea; an expensive way to slowly destroy the ‘delta’ while increasing evaporation losses and interfering with the movement of river life,all processes which are irrationally discounted by our economic system. If one wants to reduce loss of interstate freight time, flood-free engineering of the Summerland Way avoids as much of the Clarence flood-plain as possible.
There is no overwhelming reason for major dam works on the major tributaries as yet.
Spanglers – further on greenhouse & dams here’s another political view http://www.riversymposium.com/2007_Presentations/B1_McCully.
The only Australian research that had been done was on Tasmanian dams, which found emissions were around 30 per cent of a natural gas plant – a much higher reading than US dam emissions, Mr McCully said. Those readings would be higher in hotter parts of Australia, especially northern Queensland, he said.
I guess you can either or dismiss the assertions. However the dam builders are now well aware that storages are more than likely a major methane source.
However back on dams. Whether the Clarence needs the full flood flow to maintain ecological function is a moot point. Certainly the water that has just gone past would have considerable economic value for cotton irrigation in the Gwydir system. Does it add up – dunno. Cotton – horror of horrors – but strangely greenies love wearing it. Most of us do.
So there may be a compelling economic argument in a water constrained MDB.
However all dams are barriers to movement – so I’m not sure what the micro-satellite DNA and tracking electronics would tell us about species dispersal and genetic structure of the fish fauna. Certainly research in the upper MDB and Fitzroy is surprising and not what Mottsa may think – lots of movement on the first small flush and then little after in one study. We probably don’t know half enough.
For a change, I can agree with Luke on the issue of research on what sort of seasonal flood/flush is best for the dependent aquatic species. We don’t know anywhere near enough.
But we can assume that an early flush will send smaller fry etc into the ocean and these are likely to have a lower survival rate than larger fry in a later flood. More time in the nursery means a larger fry on departure.
We can also assume that a flood does not need to be a major flood to perform its essential ecological function and we can also assume that most of the populations that need to be flushed will go on their journey in either a medium size flood or the initial stages of a large flood.
We can also assume that large floods also play an important role in clearing out the sediments that build up in the milder seasons. But we know that it does not follow that more flooding equals better ecological services.
What we don’t know is how intense, and for what duration, a flood must be to perform all of its functions properly. We don’t know the mix of volume, duration and timing that is needed to produce the optimum flood, or rather optimum range of floods, for maintaining the normal range of variation in populations of relevant species.
We don’t know the extent of the margins that nature has built into the life cycles of riverine species. And until we know these margins then any assumptions on the required volume of so-called “environmental flows” will be pure guess work.
When these core attributes of river flow are known for each system then we can get down to working out how a major storage capacity can be used to ensure that all these needs are met, and then allocate the surpluses to other users.
What do know for certain is that man is fully capable of exercising judgement and skill, and investing capital, in a way that can achieve substantial efficiencies on the very wide set of redundancies that nature normally works on. A large dam can, for example, fully capture an early flood that would flush out fry before they are fully ready, and hold that water, and even accumulate a number of small flow events, to be fully or partially released, in the best volume, over the best duration, to produce the optimum set of ecological services.
And having discharged this core obligation, capturing the remaining flows for distribution to users without guilt.
Our problem is that our decision makers and research community are so lacking in this vision that they don’t even want to know. They cannot even begin to gain the knowledge needed to make it happen. The best these turkeys can do is compare base percentages and make ignorant guesses as to the appropriateness of them and boorishly rant about more equalling better and no allocations being the best allocations. They are, as Christopher Isherwood put it, “those small men with frowns, beheading daisys with a stick, that one finds loitering without vision, in the foothills of great ideas”.