ACCORDING to Australian aboriginal mythology Bunyips are monsters that live in rivers. According to Ron Pike, an Australian who has spent his life working with water from the Murrumbidgee River, much of what is being claimed about Australian rivers is as unreasonable as a belief in Bunyips:
“The lack of flow volumes in the rivers of the Murray Darling Basin (MDBC) in recent years is not due to irrigation and over extraction. The facts are that without the storages and the irrigation industries, conditions would have been considerably worse. Throughout the MDB there is presently more wetland habitat than there would have been had there been no irrigation for the last several years. It is also wrong to suggest that increasing stream flows by releasing extra water from storages, somehow benefits the environment. It makes no appreciable difference to the environment whether the Murrumbidgee at say Narrandera is running at 3,500 megalitres per day or 25,000 megalitres per day. The flows in both cases remain within the banks and do not, and cannot, water the floodplain or most wetlands.
Reading the journal notes of the men who were the first explorers of the rivers of the Murray Darling Basin (MDBC) gives us a number of facts which are still relevant if we care to understand the system and wish to maintain it for the good of future generations.
The explorers note that once the rivers of the MDB leave the hills and commence their meandering journey across the plains, the stream flow is twenty to forty feet below the surrounding flood plain. Only at the Macquarie Marshes, the wetlands of the lower Lachlan and to a lesser extent above the Bahmar Choke in the Murray do the rivers flow above their bank, other than in large floods.
Most of the other rivers in the MDB, including the Murray have the same characteristics; once they reach the flood plain (it is on the flood plain that the wonderful River Red Gums grow and also the vast but irregularly watered wetlands preside); they flow well below the surrounding plains. Therefore these wetlands are only ever flooded in periods of excessive catchment rainfall which causes the river to flow above its banks. When this happens the wetlands explode in a volcano of abundant life across all species natural to this environment.
A magnificent, spontaneous and symbiotic food chain develops only limited by the environment in which it exists, and sadly it seems, not understood by many present day commentators.
In order to understand the system it is necessary to have some understanding of water volumes.
A megalitre is 1 million litres or 1000 cubic meters. It is the measure that is used for all sales and purchases of water throughout the MDB. It is also used by all Municipal authorities. For those who want a comparative picture, an Olympic Pool is around 1.7 megalitres, depending on depth and width.
In the case of the Murrumbidgee, the photograph shows the river running at around 2,400 megalitres per day. If a release from both Burrinjuck Dam (full capacity 1.03 M megalitres) and Blowering Dam (full capacity 1.6 M megalitres) of 20,000 megalitres per day were to be made in this situation, it will not put water onto the flood plain. A flow of 40,000 M/d will put some water into a few low lying Billabongs and backwaters, but will not put water on the floodplain. All that would be achieved is a high river flow for a few days. Most of which would run to the sea and to waste. The same applies to most other valleys in the MDB.
To put water onto the Murrumbidgee floodplain and fill the wetlands requires volumes in excess of 150,000 megalitres per day. This is far beyond what is possible from existing storages. It will only ever be achieved by Mother Nature and man has no influence on its recurrence and little on its magnitude. As an example of what is required to flood any of the MDB river valleys, the Murrumbidgee flood of September 1974 is enlightening. Following heavy rain in the area of the ACT, Burrinjuck dam quickly filled and a day later there was almost 400,000 megalitres per day going over the spillway, plus the outlets were fully open. There was sufficient water going down the Murrumbidgee Valley to fill Burrinjuck from empty every two days.
While this flood reached a height of 9.19 meters at Wagga Wagga it was not an exceptionally large flood historically. This and greater volumes are required in most of the river valleys of the MDB to water the wetlands.
Our early explorers and settlers recognized the huge flow changes that occur in our river systems. They were also aware that this old river system was very unpredictable. It moved from abundance of flow to completely dry at irregular intervals.
While a vocal minority of modern man seems unable to accept these historical and present facts, we are prone to make bad decisions on behalf of future generations. From the 1840s to present time we do have sufficient records to support the variability of stream flows within the MDB. One of these is at Wagga Wagga where records have been kept since 1844 and show that there have been 77 floods over 8.23M. Note a flow of 3,000 mgs. /day is a river reading of approximately 1 metre at this site.
To stress the point, the Murrumbidgee at Wagga has to rise 7 metres above normal flow to reach flood level and water the floodplain. This requires volumes far in excess of any storage on the system.
Ron Pike now lives at Coff Harbour on the NSW Central Coast in Australia. Read Part 1 here. Photograph of the Murrumbidgee River at Gogeldrie taken on September 3, 2008.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
here’s the 1991 flood at Wagga – taken from the north side of the Olympic highway looking towards Wagga. It was a lot of water.
http://users.tpg.com.au/johnsay1/Stuff/wagga_1991.jpg
Interesting to see that Ron says 1956 was the wettest year in the MDB, in the Hunter it was the previous year.
From http://www.hunterweather.com/events.php?id=41
“The Hunter floods of 1955 are placed in history with Cyclone Tracy, Granville, Newcastle Earthquake and the 1939 bushfires as being an infamous disaster of the 20th century.”
“The 1954 – 1955 was dominated by a La Niña (opposite to the El Niño) event. The Southern Oscillation Index (SOI) leading to February 1955 was in the positive for nearly 8 months, peaking at 15.2 by the end of February 1955. The winter of 1954 was very mild. August 1954 still stands at as being one of the warmest August in history. Monthly rainfall totals from October 1954 to February 1955 were above average across a large area of the Hunter. Many locations received there highest rainfall totals on recorded.”
Still no evidence of claims being made which are “as unreasonable as a belief in Bunyips” I notice. In fact, the only thing approaching that level of unreason is your unsupported assertion that river flows are meaningless unless they reach the Murrumbidgee floodplain.
“symbiotic food chain”
WTF? Hilarious. You know this is a biologist’s website, right?
Very interesting article Ron, I’ve lived on the Murray all my life and the big flood years were the 1950’s and 1970’s. This of course was also in the middle of the 30+ year cool phase PDO ( 1946 to 1977 ).
Since then we’ve experienced warm phase PDOs and a dominance of El Ninos so our bad drought can easily be explained if one doesn’t embrace the AGW nonsense.
Hi FDB & All,
The Article has been edited, so here are the Bunyips:
First Bunyip:
That lack of flow volumes in the system in recent years is due to irrigation and over extraction.
Facts are that without the storages and the irrigation industries, conditions would have been considerably worse.
Throughout the MDB there is presently more wetland habitat (pictures provided) than there would have been had there been no irrigation for the last several years.
Without the river storages, the Darling, Castelreagh, Macquarie, Lachlan, Murrumbidgee and a host of smaller streams would have all been dry for much of the last several years.
The landscape would have quickly resembled that described by Sturt in 1828-29 in the previous article.
Second Bunyip:
That increasing stream flows by releasing extra water from storages, somehow benefits the environment.
It all stays within the banks and has no impact on the wetland environment which is all outside the banks.
Third Bunyip:
That having the State buy back existing irrigation licenses will somehow solve this perceived problem.
This is the biggest, silliest Bunyip of them all.
The State already owns all the water and is under no obligation to deliver license entitlements to irrigators if it believes other needs are greater.
The State already does this!
If the State wishes to release “environmental flows” from any storage at any time it can do so without buying water from anywhere.
Both Political Parties are guilty of this classic case of Government nonsence, identifying a problem that doesn’t really exist ( except in the Media), incorrectly diagonising it and then applying the most expensive but incorret remedy. To the rousing cheers of the Media.
Fourth Bunyip:
That the River Red Gums are dying because of lack of “Environmental Flows.”
This is and always has been false.
These wonderful old eucalypts of our river system are ideally adapted to live and survive through long periods of low rainfall and lack of floods.
Do those who claim that lack of “environmental flows” are killing these great trees, ever stop to consider how they survived through many periods of no flooding before as detailed in the Murrumbidgee flood records above.
I have a number of photographs and other data to support this argument.
That will do for now.
Pikey
When those pioneers first discovered the Murrumbidgee river I’m sure they jumped off their horses and jumped in to cool down, something you may be cautioned to do today as it is FREEZING!! More than 10 mins in there and you start to get a headache even though it’s 40C in the shade. This is due to the water coming from the bottom of the dams when released through the power stations.
Surely this must have a horrendous effect on the river’s aquatic life??
Great article, Ron. And a whole mob of ugly Bunyips too!
In my region (the upper Gywdir/Macintyre) the catchment authorities have warned us the CSIRO forecast increasing drought events in the future. Not that these forecast bear any resemblance to observation. Still, most farmers are building or expanding dams, as you do.
As farmer Pete note in Part One: “Much of what we’re doing as “Landcare” and high production farming is aimed at slowing or reducing run-off, retaining and using rainfall in situ.”
Smart farmers are learning how to maximize sustainable profit margins. This usually means lower gross income and stocking rates and increased use of scientifically sound soil maintenance schemes. Marginal land is returned to bush.
Lower stock-rates with more productive paddock management techniques that dramatically increase the organic matter content are all designed to maximize water use efficiency.
Granted, it’s a few megalitres here and there, but it must add up to something. A series of dams on a dry creek bed fill from the top down. On the micro-scale, this has had an ameliorating effect on local creek flood levels, at least before catchment saturation occurs.
Creek beds that would have flowed all the way to the river 4 to 8 times a year 25 years ago with one dam, now might have 5 dams with well managed terraced paddocks and flow all the way to the river less than 3 times a year.
Isn’t a local example of increasingly dammed creeks and better managed soil a simple scale model for what’s occurring in much larger MDB system?
Why don’t the millions (?) of new 1 to 10 megalitre ponds built in the last 15 years have some measurable cumulative effect when extrapolated across the entire basin especially combine with modern soil management techniques.
No doubt, MDB storage capacity is insignificant to trip up a good catchment saturating flood, yet couldn’t it smooth the rate of a borderline flood flow to below flood stage, at least when the dams are low?
As farmer Pete commented maybe our parameters for the basin’s flow was set too high by the poor land management techniques of the mid-20 th century, which encourage high run-off?
Have you factored in all the hydrological factors besides the obvious big reservoirs’ capacity of the MDB in your calculations? Is there a current inventory of the millions of small farm dams? Perhaps by satellite survey? Can you calculate in the trends in the run-off coefficient, assuming such a constant exists for the MDB?
I think some South Australians might argue with you on the importance of the flows heading their way.
“Since then we’ve experienced warm phase PDOs and a dominance of El Ninos so our bad drought can easily be explained if one doesn’t embrace the AGW nonsense.Since then we’ve experienced warm phase PDOs and a dominance of El Ninos so our bad drought can easily be explained if one doesn’t embrace the AGW nonsense.”
Not really – just shows you haven’t read anything outside your comfort zone. And factually wrong.
Indeed, Luke. See here, hot off the press:
http://www.nasa.gov/topics/earth/features/jason-20081209.html
Mark don’t try arguing with Luke, because you see he is a fundamentalist believer and detests facts and the truth.
I repeat there was a very long , strong CF PDO for 30 years ( 1946 to 1977 ) and during this period we had cooler temps ( some claimed a coming ice age ) and locally ( Aust) the MD Basin recieved much higher rainfall and severe flooding.
All this is factually self evident but don’t expect the true believers to bother about mere facts.
So just tell us one thing Neville – have you ever made an attempt to read any of the papers I have tabled on this issue over the last year.
You see you simply haven’t had all cooler temps at all. And the whole MDB is flooded is it? Why was the PDO “strong”? So do you think an ice age is nigh?
So who is the fundamentalist believer then?
“factually self evident” ??
Think for yourself for once.
(Yes Mark I know)
Looking at Ron’s chart it seems that the longest duration of good ( or consistent ) rainfall must have been 1970 to 1993. This period of 23 years is by far the longest duration from 1844 to the present when useful rainfall fell on this area of the basin.
There hasn’t been a flood from 1993 to 2008 ( 15 years ) but back in the 19th century there wasn’t any flooding from from 1853 to 1867 ( 14 years) so we can hardly claim this is unnatural.
Unfortunately it has been very dry and we’ve suffered a long drought but the facts remain that in the last 50 years we’ve also experienced the most rainfall and consistent flooding in this area of the basin in 164 years.
In other words the last third of the record is the wettest by far.
Luke,
I would be a little cautious about sneering about ” Ice Age” belief, with today’s news that London is 0.17 deg C above the average temp which froze the Thames during the Little Ice Age – with some meteorologists now expecting the coldest winter for 1000 years.
I know most of you disciples do not believe in the Little Ice Age, but people who do are entitled to worry a little about the current trend.
I wonder if those “activists” who were frolicking in the water with their protest banners at Cancun will stage a reenactment in or maybe on the Thames ?