Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for January 31, 2007

A National Plan for Water Security (Part 2): The Issue of Over-Allocation

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The Australian government’s new $10 billion, 10 point plan entitled ‘A National Plan for Water Security’ states that there is a need to address “once and for all water over-allocation in the Murray-Darling Basin”. This is point 4 of the plan.

So what does it mean to be “over-allocated”?

According to The Plan “over-allocation is where more entitlements have been issued in a system than can be sustained.”

What does this mean?

According to a recent report ‘Water Use and Regulation’ by the ANZ bank:

“The National Water Commission estimates that as of 205, 1 percent of Australia’s 340 surface management areas and 5 percent of 367 groundwater management areas were over-allocated (that is over 100 percent of sustainable water levels were permanently allocated for extraction and consumption), while another 13 percent of surface water and 23 percent of groundwater areas were ‘highly developed’ (that is 70-100 percent of sustainable water was allocated) putting them at greater risk of temporary over-allocation during dry periods.”

I find the concept that over-allocation means over 100 percent of the water in a system has been allocated unusual and extreme and I have contacted the Nation Water Commission asking for more information and the specific reference. (deleted following comments below from Ian Mott and Wally, see below)

In the relevant document from the National Water Initiative there is no specific definition of ‘over allocation’ and comment is made that each state and territory has used different criteria.***

In the development of ‘Water Allocation and Management Plans’ in Queensland under the Water Act 2000 the arbitrary figure of 30 percent was used; that is if more than 30 percent of a river’s flow is diverted it could be considered over-allocated.*

How much of the Murray Darling Basin’s water is diverted?

Under natural conditions it is estimated that 46 percent of the 24,000 gigalitres that flow into the Murray-Darling Basin is consumed by wetlands and floodplains with the remaining 54 percent flowing out to sea. Now, with all the regulation it is estimated that 11,580 gigalitres, or about 50 percent of the water within the Murray Darling Basin, is diverted for irrigation.**

Based on the estimates in ‘River Losses and End of System Flows’ (MDBC, November 2003, and ignoring the 1,200 gigalitres from Inter-Basin Transfers), it would require that the government buy back about 4,425 gigalitres of water entitlement for the system to be at a 30 percent level of extraction.

If government paid a probably conservative $1,000 per megalitres for permanent entitlements then I estimate they would need about $4.425 billion.

This is an awful lot of money and the government currently only has $3 billion in the budget for buying water entitlements.

Is it worth it? What would be the net benefit of returning the 4,425 gigalitres to the Murray Darling Basin?

The Murray-Darling Basin covers about 14 percent of the land mass of Australia but mean runoff is only about 24,000 gigalitres or 6 percent of the Australia’s total mean annual runoff (Australian Water Resources Assessment 2000, pg 25).

While relatively little water falls within the Basin (6 percent), most of Australia’s water infrastructure has been developed here including the Snowy Mountain scheme build in the 1950s to drought proof the region.

The Murray River has essentially been turned into an irrigation channel with its headwaters part of the Snowy hydroelectricity scheme, four large dams and 13 locks along the way and the system ends in a series of barrages at the so-called Murray mouth.

The Murray River is kept artificially high most of the time as water is moved from the dams which are mostly at the top of the Catchment to irrigation areas downstream and also to meet Adelaide’s water needs.

The Darling is a very different system and less regulated.

In summary, ‘A National Plan for Water Security’ assumes over-allocation in the Murray Darling Basin but does not explain how this was determined and what an acceptable level of extraction might be. Assuming that 30 percent of pre-development flow levels is a reasonable level of extractions, the government would have to buy back about 4,425 gigalitres of water and is likely to cost more than $3 billion.

Buying back this water is likely to significantly impact on agricultural production in the Basin and the rural communities in irrigation areas.

There are already significant environmental flow allocations for the Murray River. Given the Murray River is already a highly regulated and somewhat artificial river system I doubt that the environmental benefit from the return of additional water would be significant. What would the environmental benefits be for the Darling River system?

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This is the second in a series of posts on ‘A National Plan for Water Security’, Part 1 is here: https://jennifermarohasy.com.dev.internet-thinking.com.au/blog/archives/001859.html

* I can’t find a good reference or link for this, Luke can you help?

** Based on ‘River Losses and End of System Flows’, published by the Murray Darling Basin Commission, November 2003. Can someone find the document on the internet for me?

***Changes made to this post at 12noon on Friday 2nd February.

Coral Reefs May Benefit From Global Warming

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ON Friday in Paris the UN’s Intergovernmental Panel on Climate Change will launch a new report, Climate Change 2007: The Physical Science Basis, with an up-to-date assessment of likely temperature rises because of global warming. Three related reports will be released later in the year, including a report on the likely effects of the rise in temperature. The report on impacts is likely to include a chapter on Australia and a warning that corals on the Great Barrier Reef could die as a consequence of global warming.

The idea that the Great Barrier Reef may be destroyed by global warming is not new, but it is a myth. The expected rise in sea level associated with global warming may benefit coral reefs and the Great Barrier Reef is likely to extend its range further south. Global threats to the coral reefs of the world include damaging fish practices and pollution, and the UN should work harder to address these issues.

Read the complete article here: http://www.theaustralian.news.com.au/story/0,20867,21144521-7583,00.html

More Fuel Reduction Burning, More Fires: A Note from Bob McDonald

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Bushfires have burnt more than 1.2 million hectares (4,600 square miles) of Australia this summer.

Some blame the ferocity of this year’s fires on global warming, others on inadequate control burning claiming that fuel loads in many forests are too high.

Bob McDonald has a very different perspective suggesting that both the frequency of bushfires and fuel reduction burning has increased over the last two decades in parts of eastern Australia and that in some situations the best strategy is to not undertake any controlled burning as potential fuel, including leaf litter and wood, will be quickly broken down by termites, bacteria and fungi:

“The frequency of both fuel reduction burning and fires have increased over the last twenty years in many locations. There may be no relationship between the two, but I suspect that in some situations more frequent burning is contributing to more fires.

My grandmother was saved by her father cutting and bleeding her hand when she was bitten by a snake. He didn’t actually do the right thing but she believed he did – was calm and survived.

If anyone had argued with the my great grandfather on the day he cut his daughters hand I likely would not be here to write this – so I respect all those views contrary to mine on an issue for which many have strong and personal or professional views and I am prepared to be wrong – but first we need to have an objective look at what has happened with fuel reduction burns in the last twenty years on a site by site basis.

I have fought fires in several places and I am interested in questions relating to what does not burn, when vegetation burns, how hot does it burn and which fires can ignite what kinds of dead wood.

Wire grass, for example, explodes but you can run through it without getting burnt.

In the 1983 Ash Wednesday Fires at Mount Macedon (on a south westerly wind) frequently burnt as well as bush with that went up in a crown fire and also burnt. A fire from the north just 10 days before the Ash Wednesday Fires, a wet gully of ferns and old trees on the south side of the Mount Macedon ridgeline held up a grass fire for two hours enabling water bombinmg and eventually being put out.

In 2003 roughly 500,000 hectares of forest from East Gippsland to Canberra was burnt. When fires two weeks ago reached this area, burnt less than three years ago, they not only burnt but ‘took off’. This would suggest that in some situations re-growth is more flammable than un-burnt areas and that in some cases a significant amount of fuel reduction burning could actually increase the frequency of bushfires.

In East Gippsland, while developing a Community Fire Protocol to manage fuel reduction burning, locals pointed out that rainforest gullies slowed fires and it was a good idea not to burn them in fuel reduction burns.

In coastal rainforests strips in northern NSW there is no fuel the litter life is so intense that even leaves remain in a light single layer and fallen timber rapidly becomes soil.

Termites play a big role here, along with fungi and bacteria. If it was burnt this forests’s capacity to rot timber would be significantly reduced.

It will take time for people to feel comfortable with letting the bush grow out in places where no-fire is, in my opinion, the best hazard reduction strategy. All vegetation burns, dead and alive, but some burns better than others. Fuel reductions fires in sandy country in the south that generate braken invariably increase braken denisty, height and the fire hazard – and often kill thin barked eucalypts like Manna Gums, for instance

Bob McDonald,
South Gippsland.”