Greening the Outback - The Bradfield Scheme Reassessed.

[old man emu]

In 1938, Dr. John Bradfield, of Sydney Harbour and Brisbane's Story bridges, proposed water diversion scheme that was designed to irrigate and drought-proof much of the western Queensland interior, as well as large areas of South Australia.  It involved diverting water from the upper reaches of the Tully, Herbert and Burdekin rivers in Far North Queensland which are fed by the monsoon, and flow east to the Coral Sea. It was proposed that the water would enter the Thomson River on the western side of the Great Dividing Range and eventually flow south west to Lake Eyre. In 1944, author Ion Idriess  wrote The Great Boomerang.  

In it, he added to Bradfield's idea by pointing out that Nature had already created the drainage system that would carry water from the western side of the Great Dividing Range through to Lake Eyre in South Australia. That this system works is currently being amply displayed as water from recent cyclones has reached Lake Eyre after flooding vast areas of the Channel Country.

 

Bradfield, Idriess and others of that era were not to know of the coming climate change which, this year (2025) /appears to be responsible for the massive rainfall that is now filling Lake Eyre. Also, they were not to know of the advances in mechanisation that now allow us to carry out massive civil engineering projects. In those years, the idea for Snowy Mountains Scheme was probably not much more than embryonic. 

 

The reasons for the failure of Bradfield's to get the green light in his time was most likely political, or more correctly the ability of the Queensland Government to allocate the, even then, substantial money needed to complete the engineering works. However over the years, the Bradfield Scheme has been recycled every few years in the form of feasibility schemes, revisions and hybrids, only to be dismissed or rejected once more. Often the rejections have been based on inaccurate or insufficient data.

 

It appears that while the idea to move water to where it could be useful to agriculture, various industries, population dispersion and maybe even climate improvement is most often stymied by the money needed to carry out the diversions. However, as with most things which call for taxpayer money, costs are considered in the here and now. It is extremely rare that approval is given to spend now for the benefit of future generations. It has been said that an old man will never sit in the shade of the tree he planted in his youth. Perhaps it might be good this time to think of our grandchildren picnicking in the shade of a tree we planted. 

 

 

[facthunter]

Irrigational always gets involved with Salination and INLAND there's high rates of evaporation. Most of Australia is very flat and water doesn't flow away very quickly and spreads out far and wide. Nev

[Litespeed]

Anyone want to buy a bridge, going cheap?

[old man emu]

1 hour ago, facthunter said:

Irrigational always gets involved with Salination and INLAND there's high rates of evaporation. Most of Australia is very flat and water doesn't flow away very quickly and spreads out far and wide. Nev

A couple of points to answer here.

Yes, salination is a problem that needs addressing. But now that we are aware of it  - usually due to overwatering - practices could be developed to minimise it. 

 

Evaporation: I think that the concept is that instead of irregular flooding, water would be added at the start of the system each year just to maintain a regular flow. The amount added could take into account expected losses through evaporation.

 

Spread of water: The water now spreads out due to the overwhelming amount in flood years. If the input flows were controlled, then the rivers carrying the water could be kept at near constant levels without spreading out. 

 

Speed of flow: I believe that the current flood waters are moving at a speed of about 4 kph, which is sufficient to keep the water moving downstream. If the system was kept topped up, that flow rate could be maintained.

 

One thing that hasn't been mentioned here yet is what effect the constant presence of water would have on the ecosystem. We know that after the floods animal populations explode in numbers. Would permanent water result in ever larger populations?

 

There is also the question of what effect would the evaporation of that permanent supply of water do the rainfall patterns. It is considered that the interior dried out within the past 60,000 years due to lack of rain which meant that the rivers no longer held water to be evaporated. If water was put back, would it rain more?

[onetrack]

The proponents need to re-adjust their ideas of getting water to the Interior from North Qld, and aim for the area East of the Great Dividing Range in Northern NSW as the major supply region.

 

This area suffers so much constant excess water, it seems a crying shame that it all goes out to the Pacific. A few tunnels through the GDR, and hey presto! - there's your water supply system for the Interior sorted.

[nomadpete]

8 hours ago, onetrack said:

A few tunnels through the GDR, and hey presto!

Well that sounds simple.

But the current attempts at "a few tunnels" in The Snowy is looking not-so-simple.

Then there is the cost. After borrowing all those $billions to do such a big infrastructure project, how long would it take to pay back? How do you arrange income from it, to repay the loans/interest?

 

I suspect that might discourage such a brave project.

[old man emu]

Diverting the Northern NSW rivers sounds like a good idea, BUT the idea of the Bradfield Scheme is to get the water into the centre of the country. The Murray/Darling system does not contribute water to that area.

 

There are some wrong ideas about where the water would be harvested. The wrong places are in the lower reaches of the rivers. Bradfield envisaged collecting water closer to the headwaters of those rivers in "high" country. In other words, only taking a portion of the excess. His other idea was not to bore through the GDR, but to construct channels along the contours of the land and have the water move itself by gravitational flow, just like the Romans did with aqueducts.  There would need to be places where pumping was required, but the electric power for that task could be generated by the water exiting the system at the end of the pipelines it was pumped through.

 

The idea is definitely possible from an engineering point of view. It would seem to be impossible from the financial point of view.  The question is, "Is such a financial investment that is big in today's terms worth it for the benefit of future generations?"

[facthunter]

Your solutions to the Problems are not based on fact. A Shallow river with slow flow won't carry much water without breaking it's Banks. Where is a  suitable place to build   a dam deep enough to not have a high evaporation rate/volume held?  Mt ISA DAM is 11 Metres deep and it is adversely affected by evaporation  ( Can't be relied on as a water source.).  The channel country provides the water for the lakes in Central Aust which are ALL salt lakes and only get water irregularly.   Lake Eyre is below sea level and average depth only 1.5 Metres.  The ONLY water that doesn't add salt is RAIN. Rivers become more salty as they drain more country. Irrigation  concentrates the salt in places where it's used. It's inevitable UNLESS you drain the Block and pump the water to dry out in a shallow lake. That wastes a lot of soil nutrients as well and works better on fields with a bit of slope. The drainage system is costly and prone to blockages. You have to constantly MONITOR the depth of the Water Table.  Water is too costly to over water. You have to do it sometimes in a Heat wave for example that may last for four days or More. Cotton, Rice and almonds are high water use crops that really should not be grown in semi desert areas.  Nev

[spacesailor]

Someone ,  in far north Queensland,  tried to make his own  'mega-dam ' .

Lost heaps of money  to the humongous fines for not doing things to suit the environmentally  sudo politicians. 

Even to clear ' swamp land ' & stop the mozzie plague for the towns folk . Cost one guy $ millions in fines .

 But it's great staying there now , plus the marina is good too , that he made .

 spacesailor

[old man emu]

22 hours ago, facthunter said:

A Shallow river with slow flow won't carry much water without breaking it's Banks.

Nowadays, the flooding of the Channel country is due to the sudden influx of excess water from far North Queensland. An aim of a plan like Bradfield's would be to maintain a constant, low level inflow in those rivers which would account for evaporation losses as well as the need to keep the flow going.

 

Why does irrigation lead to salinity? It did in the past, but we must have learned something about preventing it. Clearly irrigating by flooding would readily cause salinisation, but what about drip irrigation. Of course drip irrigation is great for orchards, but now we find that we can't sell the fruit grown that way.

 

Don't forget that the plan was to harvest only some of the water from the upper reaches of the coastal rivers and let the rest flow to the sea as usual. Not all the monsoon rain would be diverted.

[facthunter]

Loss of water from open earth channels is Large and people steal it. Some of those Rivers actually flow backwards at such times. The only efficient way to move water is in pipes and Pumped. Salinated land becomes Useless. You have to rest it and grow salt tolerant plants  COSTLY  and rely on RAIN to Leech some of the salt out. Trees used to keep the Water table lower and prevent/ delay salination but we Love to clear them don't we? ALL the salt in the sea Comes from the Land. Dissolved in the Rivers. Bore water is very mineralised. Rain  water is NOT. Irrigation is a problem wherever it has been Practiced for a long time.  Flood or by drip makes little difference unless you collect and dispose of the salt. Natural flooding will move some of the salt out.  Where evaporation takes place, the  Salt will concentrate.  Nev

[onetrack]

One of the factors in the Bradfield Scheme that may not have been taken into account, is ensuring reliability of food production and reducing losses to growers by moving food production inland. I don't know how many times we've seen massive production losses and intolerable grower losses when natural weather events on the East side of the GDR have decimated crops and vegetation - cyclones especially in Northern Qld.

 

During WW2, substantial amounts of vegetables and fruit were grown in inland areas, especially along the Stuart Hwy in the N.T. These increased levels of food production were responsible for Australia becoming the primary food supplier to ALL Allied forces, especially the U.S. Forces, during the course of the War.

 

https://www.awm.gov.au/collection/015464

 

https://www.awm.gov.au/collection/C34614

 

https://viewer.slv.vic.gov.au/?entity=IE149973&mode=browse