Ian Mackay [1] has just returned from visiting south east Queensland’s many water storages. He clocked up 1,800 kilometres over the four days and this is what he found:
1. In pictures: http://www.stoppress.com.au/ .
2. In words:
“Dam after dam, dams well away from areas of population pressure, were well below critical level. Several were even at zero.
It was seeing the two and a half metre tree growing just a little above the waterline at Moogerah Dam, though, that really drove it home.
Plainly the dam hadn’t been filled beyond this level for years.
Dates scrawled at the side of the spillway wall, indicating when the dam had overflowed only confirmed it. There was the mark for the memorable Australia Day floods of 1974, but nothing after 1976. The towering, impressively curved dam wall, tightly wedged between two massive hills, had been touted as something of an engineering feat when completed in the early sixties.
Despite all the hopes behind its construction, it was clear that it had been holding back a dwindling water reserve for years.
Moogerah Dam — the name means either “place of storms” or “meeting place of storms” depending who you ask — is currently holding only 7% of its capacity.
The water ski cottages hugging what was once its shore line and the twice-extended boat ramp tell the tale of a water level that has receded over a much longer time period than just the last few years.
One friend tells me of watching enormous eels thunder over the spillway back in the early seventies. Another speaks wistfully of water skiing over the top of what is now a great isthmus jutting into the dwindling pond. Tall grass now covers the spillway area and fishermen drive the considerable length of the isthmus to cast a line. Pelicans, stilts and cormorants share the receding shoreline with grazing cattle in scenes that wouldn’t be out of place around a drying billabong much further inland.
But Moogerah is far from alone.
Most of the Sunwater storages throughout the southeast are well under a third full [2].
Nearby Maroon Dam, which also drains the impressive towering peaks of the Border Ranges stands at 21%; Bjelke-Petersen Dam collecting water from a wide catchment in the South Burnett, including the Bunya Mountains holds just 3% of its 125 000 megalitre capacity.
Atkinson Dam, near Lowood is at 0%; its picnic grounds understandably deserted, its remaining water puddle far off in the distance behind the water skiing signs.
All these dams share a common thread of optimism, the hope that the provision of a dependable water supply would somehow “drought-proof” the state and facilitate enhanced agriculture and easier living. To many who share this dream that dams equate to a certainty of water supply, the present crisis is wholly attributable to our not having added to our portfolio of existing dams.
Now, four decades on, it might be as well to reflect on the reality.
South East Queensland gets nightly updates of the levels of the major domestic storages. Somerset, Wivenhoe and North Pine Dams are collectively at around 29%. These figures look almost respectable compared to those previously mentioned, but anxiety about their low levels has lead to severe restrictions.
Property owners on the shores of Somerset Dam speak of having to regularly extend their fences out into what had been dam, of their cattle now grazing on land recently exposed and now covered in grass.
The simple fact is that our dams are failing us.
It’s not the engineers’ fault. They built dams that held back water when it rained, but there’s that other variable that is well out of the control of every engineer, and also, as he has repeatedly rued, our Premier.
“I can’t make it rain,” says Peter Beattie.
What he could do, though, is recognize that our water crisis comes from an almost total reliance on dams for water supply. Dams in the area of greatest population growth aren’t in fact the lowest. Changing rainfall patterns mean that Moogerah is getting fewer of the storms that gave it both its name and its desirability as a dam-site.
Instead, his assessment of the situation is that if our existing dams aren’t holding enough water, then plainly we need more of them……… if your wallet doesn’t contain much money, then obviously you need more wallets.
His newly announced additions include a mega-dam at Traveston across the Mary River, a smaller dam at Wyaralong across Teviot Brook near Boonah and raising of both Borumba and Hinze dams and a few other storages as well.
It’s an assessment he hopes will be shared by voters, at least those who still share that axiomatic “dam equals more water” connection. Many though, are questioning how dams that can’t possibly begin to fill until at least 2011 will be any use at all in a crisis that could well crunch in just two years time if significant rains don’t fall.
The Beattie government’s newest, the Paradise Dam that drowns the Burnett River, northwest of Childers, was recently named in an international list of failed dams. It was hoped that after the wall was completed last year, the dam would fill quickly but it is currently at only 15%. It is an expensive fulfillment (no pun intended) of an electoral promise for which we’ll still be paying years hence.
You can understand why there’s far more outcry about the Mary and Wyaralong Dams than from just those who stand to be displaced. Councils the length of the Mary have spoken out in opposition, and rural groups, environmentalists and church groups have added a long list of concerns.
Many are comparing Premier Beattie’s approach and vision to that of Joh Bjelke-Petersen.
Making the long walk, down through the cracked mud toward the receding shoreline of Bjelke-Petersen Dam, you can almost feel the vision splendid evaporating as surely as the dam’s contents.
While many farmers we encountered were making the most of the opportunity to excavate and deepen their dams in anticipation of eventual rain, no such activity was taking place in the bigger dams. It seemed it was simply easier to just build a new one.
At a time when most water authorities are diversifying their supply options, shouldn’t a first priority be reflecting on the success of the status quo?
The red dots tell the story.
Without good run-off rain, a dam is just an expensive wall.
It’s time we faced the fact that our dams aren’t working.“
———————–
[1] Ian Mackay is a teacher, poet and environmentalist from the Mary Valley. For the last ten years he has been President of the Conondale Range Committee, one of the Sunshine Coast’s longest serving environment groups.
[2] Sunwater information comes from www.sunwater.com.au click on lower left hand information option.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
It seems to me that there are a number of gaps in Mr Mackay’s logic. The amount of water stored needs to keep pace with the substantial population growth of the area — it hasn’t and this is the main problem. If the Wolfdene dam had been built, for example, we would see significant water in it (viz Hinze Dam) and also much more water in the existing dams because we wouldn’t have drawn down on them so quickly. There is no logical reason to say that the dams will never fill again, it is just a case of having to store sufficient to see a growing population over a prolonged drought. Good planning and courageous political action will take care of that. Dams are the base load suppliers — recycling and private tank storage can have their place but they will never replace dams. Desalination is a furphy for large scale supply – it is criplingly expensive. So, if you believe that dams are not the answer, how many dam walls do you want to knock down and do you have a programme to stop people migrating here from other states because there isn’t enough water? I guess it probably comes down to whether you subscribe to the notion that climate has changed to permanent drought or whether this is just a statistical event.
David, you must have been talking to the same “experts” that Peter Beattie uses, otherwise you could not have got it so wrong.
Climate has not changed, & we are not in a permanent drought. This year we are 21mm above average rainfull for the year to date. In fact, this decade, to date, we are 455mm above the same period last decade, & this is about average.
So much for the 100 year drought line.
One of the few things that Goss got right was the canning of the Wolfdene dam, which was to be on the Albert River. The Alberts catchment is to the north of the border ranges, & the west of Lamington Plateau, in a huge rain shadow. The Hinze dam has a miniscule catchment to the east of Lamington, not in a rain shadow.
In the recent rainfall event, that filled the Hinze dam, the Albert did not get much over a meter deep, [by 10 meters wide] & its total flow would have put less than a meter into Hinze dam.
The Albert has only managed to run “a banker”, [filled its channel], once in the last 16 years. Its damming would have done sweet BA for Brisbanes water supply.
Are you starting to get the picture now? We don’t get useful runoff, into our dams, unless we get major rainfall events, [EG cyclones]. Years of average rainfall will see them slowly empty, as has happened.
The fact that Maryborough regularly suffers water shortages, should tell tou something about the Mary’s catchment, & its suitability to supply Brisbane.
An inch of rain on your yard will give you green grass, but that same inch on your roof will give you over 5000 liters in a tank, assuming average house size. With Brisbane’s rainfall, the average roof will produce 175,000 liters of water, or more, in an average year. Enough for any family.
I believe its bordering on criminal to flush this, your water into Morton Bay, then demand people be thrown off their properties to supply you with their water.
Dear Hasbeen
No disagreement with your statement “With Brisbane’s rainfall, the average roof will produce 175,000 liters of water, or more, in an average year. Enough for any family”.
But you still have to store that water, same as a dam stores water, and you still have to allow for periods of no rainfall and less than annual average rainfall, the same as engineers have to do in selecting dam sizes and sites.
Based on daily water use, you would require in Brisbane, a storage tank greater than 15000L to supply 23 days water use. No rain in that period and your tank (“dam”) runs dry. If you put in a 33000 L tank you get 51 days supply. You put in a piddling 5000L tank you get just over a week’s supply.
Where to source urban water supply should depend on cost of storage and distribution, a fact which has almost been been completely overlooked in all the discussion on future water supply in SE Qld.
Blair
Gidday Hasbeen,
Any chance you could please specify the location, data source, is this from a BoM station ? etc and post the annual rainfall numbers behind your statements above, “This year we are 21mm above average rainfull for the year to date. In fact, this decade, to date, we are 455mm above the same period last decade, & this is about average. So much for the 100 year drought line.”
And where you say, “..& this is about average.”. I wondered what period you are averaging ?
Warwick, BOM does not give rolling totals for each weather site but they can be easily constructed from the monthly data. “From May 2005 to April 2006, Logan Water Treatment Works in the city south had 1,245 mm, 18% above the average 1,058mm”. See “Crisis? What water crisis?” at http://ianmott.blogspot.com/ or you can go to BOM and do your own calcs at http://www.bom.gov.au/climate/dwo/IDCJDW4073.latest.shtml
And Blair, The average water use is 700litres/day or 255 Kilolitres
a year and the average roof area is 250m2. that is 21,000 litres per month and it is actually very rare that a month goes by without some rain. From the article Which Tank? on my blog (url above) you will see that a 13,500 litre tank in an average year in Brisbane will only need to draw 13% of the average 255 Kl use (33 Kl) from the mains system. In a bad year with only 81% of mean annual rainfall this would increase to 18%.
These figures were determined by detailed modelling of the full range of tank sizes, a range of roof areas and a range of rainfall outcomes from 1st to 9th decile.
Gidday Warwick, the location of my rainfall figures is in the Albert valley, above the Wolfdene sight.
My average figures were given to me, for my nearest weather bureau sight, by the bureau, & were for 104 years.
My figures for for the 1990, & 2000 decades are from the same rainfull gauge, in the same possition, on my property. I also have had access to the figures held by the local news paper.
EG; Average rainfall Jan to June, 540mm.
This year rainfall Jan to June, 561mm
The annual bureau average is 935mm for my area.
My figures for the two decades to date, [1990 to 1996, & 2000 to 2006] are to the end of May in each decade. They are from my gauge, but correlate very closely to the official figures for Beaudesert.
As the rainfall for June this year was 20mm more than June 1996, we can now say we are 475mm above last decades rainfall. When I say this decade is average, I am using Bureau figures.
Now, 19 inches of rain in 10 years is nothing, but it does prove the point that we are being lied to. We are not in the worst drought for a century, in fact, we are not in drought at all.
This 100 year drought is political speak for
“ITS NOT MY FAULT”.
1990 to 1999 included the 2 consecutive driest years on record, in this area, with less than 500mm for 1993, & 1994. It did, however, have a couple of wide spread major rainfall events, which generated the run off to fill dams. With out these events, our water harvesting capacity is totally inadequate for supplying Brisbane, & will always be so. Another dam on the Logan, & one on the Mary will do nothing to alter this.
Yes Blair, you have to have large tanks. I have over 50,000 liters, & this has never failed me, even in those years of less than 500 mm of rain fall.
I can see no reason why the people of Brisbane should not have to make some changes to back yards, & life styles, in order to live within their region.
As the greatest rainfall in SEQ is in the Brisbane area, & the coastal strip, up to Noosa, thats where you have to harvest your water.
I suppose you could install a huge pumping capacity to harvest storm water drains, & move the water to empty dams, but the water would cost more than petrol.
You could Reengineer the city, resume thousands of homes, & build dams. At least they would be where the rain falls, but an unlikely solution.
You can through country people off their properties, at ever greater distances from Brisbane, to build ever more dams.
Or, you can learn to live with water tanks, & with less water.
The tank option is, by far the most sensible.
Blair, I could rephrase your last sentence to read, “I don’t care about anyone else, so long as I get plenty of cheep water”. Is that what you realy meant to say?
One realy big advantage of this debate for Mr Beattie, its got the health system off the front page!
Engineers might use the historical record and conversion to runoff in planning dams. Either through climate change or bad luck SEQ inland areas have had a series of low runoff years. Runoff and rainfall aren’t the same. Russ Hinze Dam filled on one big event.
It will rain again and dams will fill. However if you want to argue that instead of building dams we should be more self sufficient then you have my attention and sympathy.
I think Blair may be arguing the cost per capita of dams vs tanks – anyone want to make a calculation?
You can have rainfall drought, pasture drought or water/runoff drought. You can calculate a 5% percentile class for any of these phenomena. Drought just does not have to be defined in terms of rainfall – although obviously the amount, timing and daily distribution is still the underlying issue.
Of course the ever so clever Yanks have things like the Palmer Index and Surface Water Supply Index.
http://www.drought.unl.edu/whatis/indices.htm
Anyway just defining drought in terms of rainfall can be too simplistic (although simple is obviuously simple!!).
Property dams are by far cheaper to build (rule of thumb $3,500 mL) but are prone to evaporation and contamination.
Another problem with dams is that more modern farming methods, deep till etc have conserved moisture and runoff is less likely. For dams to be effective you need a hard catchment area.
Dear Hasbeen
How could any rational person inteprept my statement ” Where to source urban water supply should depend on cost of storage and distribution, a fact which has almost been been completely overlooked in all the discussion on future water supply in SE Qld.” to mean I advocate “I don’t care about anyone else, so long as I get plenty of cheap water”.
Admittedly I have difficult with the concept of “cheap” water…cheap relative to what? but I want to be a position to know the unit costs of water delivered to Brisbane householders so I can make some informed comment on the debate about future sources of Brisbane’s water supply, whether it be from dams, recycled water, desalination, household tanks etc .
Yes if you have a big enough household collection area (roof) you could conceivably supply yourself with enough water….but then my grandparents and greatparents got by with outdoor toilets (dunnies), coppers to wash their clothes in, shared baths and they also had no cars and kids dying from mosquito borne diseases and gastro.
Blair
I’m also informed there are some interesting heavy metals and organics are deposited on urban roofs which one may not wish to drink .. but technology of course could filter that out – if you wanted to..
Looks like Mary valley dam has hit the scientific big time this month in Nature magazine…
Have a squiz at
http://qldgreens.typepad.com/no_dams/2006/07/the_mary_river_.html
Gidday again Hasbeen,
If you want to email me at,
inward@warwickhughes.com
I can send you the monthly BoM high quality rainfall data for;
40014 BEAUDESERT (from 1893)
40094 HARRISVILLE POST OFFICE (from 1897)
I have updated these to last month.
They both show annual rainfalls in recent years are similar to pre 1920’s and do not support the usual “worst drought” claims.
The 2002 drought seemed to herald an open season on media BS re rainfall history, see my pages;
http://www.warwickhughes.com/2002/
The BoM HQ data show it was the “Great West Queensland drought”.
Sigh – it’s the runoff not rainfall that’s the issue.
Are we saying that the engineers fluffed the design of all SE Qld dams?
No luke, The engineers got it right, given the nature of catchment vegetation at the time but since the ’70’s there has been a major regrowth event in the Brisbane Valley in particular. This has drastically altered the water yield of the catchment as pasture has roughly twice the yield of forest.
The SEQ Forest Agreement which has closed State Forests to harvesting has not helped. These forests also make up a large portion of the catchment and have all been selectively logged in the past. And this means the resulting regrowth in those forests will remain unthinned and thereby produce the LEAST possible water yield.
It is no small irony that a forest policy that was meant to protect biodiversity values at minimal cost is actually seriously impairing stream and river flows and the health of the dependent species. And the resulting $2.2 billion to augment a perfectly good and adequate dam is making Aila Keto’s little whimsy look like a very expensive indulgence of the “green shoe brigade”.
And to cap it all off, SEQ Water has been busily planting trees in the 22,000 hectares of riparian land adjoining the dams. And the research from South Africa makes it very clear that trees in riparian zones can lower stream flows by up to 40%.
But don’t worry, they know what they are doing, everything is under control, 200 spin doctors said so.
We seem to be learning from Brasil about ethanol as motor fuel, so maybe could learn from some other experiences. The north east of the country is drought-prone, and
Hall, A.L. (1978) “Drought and Irrigation in North East Brasil” Cambridge University Press
looks at drought and dams and water supply in that area. The short summary is that big dams are too expensive to leave water just sitting around awaiting the next drought.
Blair, I know that a government subsidised, big dam, water supply, supplies the cheepest urban water. Hence my little,perhaps unfair, rant at you. That, & the fact that I had to attend the last community consultative committee meeting of the Logan Basin draft water resource plan today.
My mood became darker with every page I read of the draft. I could not find one instance where the advisory committees imput had been listened to.
After 7 years, & thousands of hours wasted, some of the folk were getting very short. I was starting to feel a bit sorry for some of the public servants involved, until I remembered that they will still have a job, & a pension next year, but some of the committee will be broke by then, thanks to this “PLAN”.
Luke, we all know its the runoff that counts but there is, as yet, no way of recording runoff, so we have to make do with rainfall. Although most local resident, over 70 years, will tell you “the weather aint like it used to be”, there are a few more thoughtful ones who will refute that. In fact, some can remember similar cycles for over 60 years, on the same property.
As for the engineers, there are so few flow gauges, that,in private, they will admit, many of their figures were obtained by “black magic”, as much as science.
Most of the people who once struggled to make a neager living on farms, around here are now public servants in Brisbane. Not all country folk are stupid. Their farms are disappearing under the scrubby regrowth, good for neither man nor beast, or water catchment, as Ian says.
I can remember, sitting on my yacht, in Brisbane river, in the 70s feeling very smug, that my power was working, when night after night, the city was in darkness.
I have all the water I can ever require, so why don’t I feel smug now? Could it be that I have, at my age, developed a social conscience, or do I just hate seeing such a major stuff up?
Blair, I know that a government subsidised, big dam, water supply, supplies the cheepest urban water. Hence my little,perhaps unfair, rant at you. That, & the fact that I had to attend the last community consultative committee meeting of the Logan Basin draft water resource plan today.
My mood became darker with every page I read of the draft. I could not find one instance where the advisory committees imput had been listened to.
After 7 years, & thousands of hours wasted, some of the folk were getting very short. I was starting to feel a bit sorry for some of the public servants involved, until I remembered that they will still have a job, & a pension next year, but some of the committee will be broke by then, thanks to this “PLAN”.
Luke, we all know its the runoff that counts but there is, as yet, no way of recording runoff, so we have to make do with rainfall. Although most local resident, over 70 years, will tell you “the weather aint like it used to be”, there are a few more thoughtful ones who will refute that. In fact, some can remember similar cycles for over 60 years, on the same property.
As for the engineers, there are so few flow gauges, that,in private, they will admit, many of their figures were obtained by “black magic”, as much as science.
Most of the people who once struggled to make a neager living on farms, around here are now public servants in Brisbane. Not all country folk are stupid. Their farms are disappearing under the scrubby regrowth, good for neither man nor beast, or water catchment, as Ian says.
I can remember, sitting on my yacht, in Brisbane river, in the 70s feeling very smug, that my power was working, when night after night, the city was in darkness.
I have all the water I can ever require, so why don’t I feel smug now? Could it be that I have, at my age, developed a social conscience, or do I just hate seeing such a major stuff up?
Just thinking about the issue of most rain falling on the urban areas where it then escapes collection for urban water supply.
Has anyone ever seen a house design where water from the roof is stored in the house, e.g. walls, or perhaps underneath the house?
I know there might be a few problems (crack in the wall for instance), but wouldn’t the water also act as insulation?
And cut down on the area of land needed for a water tank on an urban block?
Hasbeen – it’s not too hard to calculate a water balance and estimate runoff. In fact the yanks use a thing called the Palmer Index for drought not rainfall.
Incidentally I wonder if everyone in BrisVegas had a tank – how much water would be removed from local creeks? Anyone have a calculation?
And what were you doing living on a bloody yacht. Sounds a bit bohemian/counter-culture to me. (I’m envious).
Russel, there were some designs, some time back, where water was stored in glass, in walls, as thermal mass. I think they were more trendy, than practical, but it should work.
Many large cement tanks [30000 liters plus] in country areas, are buried to almost ground level, to prevent thermal cycling, daily, & frost damage. With new building, these could be buried undre the house.
Luke, nothing bohemian, just I could not afford a yacht & a house, so took obvious way out, & lived on the yacht.
As far as Brisbane runoff is concerned, it is greatly increased by all the hard stuff. Roof, road, parking lot etc. Diverting some of this to storage would help reduce the flash flooding occuring in urban areas.
I find it hard to believe runoff predictions can be accurate. I can get runoff from 20mm, & none from 100mm in 24 hours. Even such things as the amount of ant activity make an amazing difference.
Hasbeen – well it’s a question of “accurate” enough. Obviously depends on how the rain falls – gently or one dollop, what the current soil water status is, the soil permeability, hard surfaces etc. But engineers and agriculturalists do do such things and test their answers on flumes etc. It’s a question as to whether make enough of an estimate to give you a long term picture. I believe they can model with success in many systems.
An obvious observation is that we have had little soaking rain of late but perhaps enough to keep things green. So enough pasture but not much surface water.
Luke
For another dubious example see the last comment at
http://www.jennifermarohasy.com/blog/archives/001215.html
There is a big difference between modelling with success and modelling with reality – it depends on how “success” is being judged, even to if “success” gives the pre-required answer. As one of the lecturers in a course on modelling put it cynically “You never let a lack of data interfere with your modelling – it only gets to be a problem if you are aiming for a realistic outcome”.
So you don’t reckon we can do a simple water balance in 2006? Ian of course models are validated/verified – that’s the point of the obsession – does it validate on independent data not used to derive the original simulation.
How does mankind execute a grand fly-by of the solar system’s planets with some modelling working?? (Voyager & Galileo probes)
Just to clear up one misconception. There is a common view that existing roof runoff in cities is not captured but this is only part true. Most houses do have guttering and this guttering already captures the roof runoff. But instead of sending it into a tank, most people direct it into an equally captured storm water drainage system from which it is then release again into the river system.
In the first instance it is entirely under the control of the house owner and in the second instance it is entirely under the control of the council.
The critical catchment capture role is already taking place and working efficiently. But both continue to regard this resource as a problem to be disposed of.
Ian Beal, we would have to be cynical about the quality of the lecturer you recieved your information from. It’s not so much that we have to use models, as the lack of investment in ecosystem monitoring of all types that forces the use of models without enough calibration/validation data with the inherent risks. Getting information from a model is usually better than wild guesses provided the model user is experienced and knows the limits of the model.
It must be poor planning indeed not to have major potential water supply catchments poorly monitored.
Richard,
A pity there aren’t more lecturers of his calibre. I think you miss the point of the emphasis, which is that the dubious reputation of modelling is precicely because modelling can be,has been, and is being done and used without verification – data-free modelling as it is known in some circles. Remember the quote comparing modelling and masturbation?
For instance I’m interested to know how validation and verification were done when there is only one stream gauge in three catchments. Yet the result of these “before management plan” and “after management plan” estimates are part of the water management plan for those streams which now governs the activities of occupants of these catchments.
A thought that the run-off figures used might be suspect comes from participating in a proposed method to calculate the size of surface storages to be allowed in this area. It allowed dams of about 3000 cu m TOTAL CAPACITY- when most of the existing ones of around 5000 cu yds EXCAVATION were going dry. Not much drought proofing in that system.
As Ian Mott points out, there is ample evidence of effect of increasing woody vegetation on stream flow, yet this obviously isn’t in these stream flow models, or current legislative requirements are in spite of such knowledge. On a creek where local aboriginal stream management included culling of excess woody seedlings, I’d be hung, drawn and quartered by law if I were caught touching woody vegetation within 200m of that creek – whose main contribution is periodic practice at flood fence restoration.
Yet (nearby)the only person with year round fishing in this area of the same creek did it by removing most trees from the creek (somewhat like the Australian Story example in ignoring official wisdom).
This desilted the waterholes, restored the known springs and even provided water in the creek right through the 2002-03 drought. Strangely there has been negligable interest from officialdom, and even mutterings about the detrimental effects on biodiversity. This seems a strange concept of biodiversity – where species are not rare, adding more of an existing species doesn’t do a lot for biodiversity – add sufficiently more and increasing competition can even reduce biodiversity. In this case a whole aquatic ecosystem has been restored, which (outside of a tree-centric world view) ought to be credited with adding considerably to the biodiversity!
And this in an area that is bright red (high salinity hazard) on the salinity hazard maps (another official modelling effort without ground truthing which has been used to attempt to restrict management options, as discussed in various other threads on this site), where there is sufficient local data to indicate this is most unlikely to happen.
Producing a model from doubtful data and acknowledging its limitations is one thing. Proclaiming a similar model as state of the art and using it in regulation is entirely something else.
For everyone else the punchline is “an essentially harmless activity for the desperate but not be confused with the real thing”.
But yes suddenly we’re banging on about salinity maps. Russ Hinze Dam did fill despite all that woodland thickening up the back of Nerang.
You can develop a simple model of runoff without getting into too much of a lather. Thickening would reduce your runoff even further. Will show our rainfall has simply produced little runoff in recent years.
The issue, Luke, is that the threshold rainfall event that was needed to produce a flow of water into most dams has been raised by vegetation management policies. And this has made the remaining rainfall events less frequent and less contributive. And the extent of this drop in the contributive value is far greater than the impact of reduced frequency of high rainfall events.
Good posts, Ian Beale.
Climate change is of only minor impact to date while vegetation change, and its treatment in policy, is the major impact. And the cost of new dams was never considered when the vegetation mismanagement measures were implemented.
Ian – I beg to differ- how much regrowth do you have in the Wyaralong catchment – looks as clapped out as ever to me – you have nowhere near done the numbers, nor analysed in the detail needed. But nevertheless good questions in scope.
The climate change horse is closing from the outside !
See http://www.csiro.au/news/newsletters/0604_water/meet1.htm
“Papers by Cai in 2005 and 2006 and published in the Geophysical Research Letter provide an insight into two outcomes of this research –
A link between ozone depletion over the Antarctic and an intensification of the super-gyre leading to a 20 per cent increase in the strength of the East Australian Current
Warming of the western Tasman Sea east of Tasmania where temperatures recorded for more than 50 years at an offshore station near Maria Island have risen nearly two degrees, and will continue.
“Warming in the latitude around 40°S east of Tasmania is the greatest anywhere in the Southern Hemisphere and we believe that is the result of changes in ocean circulation,” Cai says.
Those oceanic changes, when coupled with shifts in wind and pressure systems are influencing rainfall patterns across Australia. Water supply systems were established based on a set of climate baselines (annual total rainfall and the associated inflows) at a time when rainfall was higher than the present level, with water allocation strategies assuming stationary climate baselines. Climate variability and change over the past decades have overturned that assumption.”
Luke, here in SEQ we have had above average rainfall. From April 2005 to April 206 it was 118% of average. The June to June total dropped because of a very wet 6/2005 and the running total is now 99.5% of average. So what the @#$%^& has this got to do with Tasmanian sea temperatures? Or is it that one needs two heads to deal with your inherent inconsistencies.
For SEQ veg data and regrowth stats see http://www.dnrm.qld.gov.au/slats/ “Landcover Change in South East Queensland 1988-1997” and cross reference with remnant totals. The ‘regrowth’ totals in the tables refer to only new regrowth during the period. To get the total regrowth you need to subtract the remnant total from the total woody veg total. But even this will not tell the full story because much of what is mapped as remnant is merely regrowth that has been mapped as remnant because it has (supposedly) hit the 70% height threshold.
I revise remnant maps as part of my livelihood and can advise that most mapped remnant in SEQ has a very significant regrowth element. And “shonk central” has gone to considerable effort to ensure that there is no budget to disclose the truth.
Yes yes yes – but where’s the regrowth in Wyaralong area – maybe somehwere in SEQ – but tell me it’s in Wyaralong – doesn’t look like it to me driving past.
Go to our our favourites at: http://www.bom.gov.au/cgi-bin/climate/rain_maps.cgi
Have a look at deficits and deciles – the coast may be average of OK but the inland catchment areas are not. Look at the spatial patterns for recent years.
The Cai references indicate southern hemisphere circulation is changing – I’m asserting that lack of coast crossing cyclones and drier inland catchments is further part of that change.
Do some research on all the factors !
In various threads on this site there have been those pro and those anti GCM’s and those in between. Those pro are apt to mention a list of drivers that are now being included in these models and wax lyrical about various projections resulting. But I haven’t seen any mention of how well these drivers are included – ’tis the age of the spin-doctor after all.
This question is posed initially relative to what would seem to be an important component – evapo-transpiration. A while ago now, in an aside in a seminar, the presenter mentioned that he had just had a look at one such model and found that evapotranspiration was handled by extrapolating from a one-stomate model. I had hoped that things might have improved in the handling of what seem to be basic inputs, but have recently been reassured by some much closer to the circulation action that things haven’t really changed.
Seems an obvious invitation (to borrow from Ernest Gann) for “some totally unknown genie to piddle on the pillar of science”.
Ian – there are whole text books on land surface schema. Evapotranspiration models depend whether you’re modelling a stomate, leaf, plant, paddock, catchment, continent or planet. The Cai work is observation explained by modelling.
Luke,
I think you’re missing the message. This was like the horse and rabbit sausages – 1 planet, 1 stomate.
What has Wyarralong got to do with the catchments of existing dams that have experienced thickenning events, Luke.
And if you are having problems finding regrowth then all you need to do is look for tree trunks that are 80 to 100cm in diameter. EVERYTHING ELSE IS REGROWTH.
And it is all over the place. It is easier to find if you take your head out of the paper bag.
Ian – you a complete numb nuts (with respect of course). The argument about Wyaralong is that it is a potential dam site that will not fill. And quite close to Maroon and Moogerah which I can’t see much thickening either. You are simply hell bent on fully pushing the reduction in runoff from a property rights woe is me on the trees agenda.
Yes I’ll give you some credit for extra regrowth or thickening trees where they map them. No contest. How much I don’t know. But it has rained less in many dam catchments – check the BoM various percentile maps above. AND you have a novel climate change driver as well if you look. My personal observation is a lack of runoff events – just mainly drizzly showers.
And when we did get an off coast low off the Gold Coast and it did bucket down in the Russ Hinze catchment (despite all that thickening up the back of Nerang)- it did actually fill the dam!
Luke,
It’s an odds game. A drought is a rare event on the low side of rainfall. But once you’re there, it needs a run of rare events on the high side to wet things up again. Add additional impediments to wetting up, then you need rarer events on the high side to get the same result.