05 July, 2011

Murray Darling Basin Statistics

Remember that book "Lies, Damned Lies and Statistics"? Well,we are seeing that theme borne out in the debate leading up to the next iteration of a Murray Darling Basin Plan. Leaks from Canberra have suggested that the new report will state that 2,800 GL should be recovered "for the river" by way of the purchase of Licenses covering this amount of water. Some are arguing that at least 4,000 GL's should be recovered.

Where would 4,000 GL's go this year when there is more water around than "you can poke a stick at" and it would only add to the 000's of GL's flowing from the Murray mouth. In the drought years where would the extra 2,800 (or 4,000) GL's have come from when there was no water for anyone.

Critics will leap at me and say we are not talking specific annual figures,but averages. However, when the spreads around the average are so enormous surely average figures are meaningless.

Let's look at how the system really works. All irrigation licenses are subject to seasonal allocations. A license without an allocation represents phantom water. No allocations means no water. Thus we have a self regulating adaptive system that governs irrigation extractions in line with available water. Critical human needs and designated environmental needs have priority over irrigation. All of this is spelled out in Water Sharing Plans.

The much criticised "Guide to the Murray Darling Basin Plan" constantly refers to 13,700 GL's as the irrigator's surface water usesage figure. A close reading of the report reveals that that number is an average.

According to the Australian Bureau of Statistics, actual extractions for irrigation in the Murray Darling Basin over the last five years have been-
2005-06 7369
2006-07 4458
2007-08 3141
2008-09 3492
2009-10 3564
These figures suggest that the allocation system is working well. In a highly variable flow regime an adaptive methodology such as this would seem ideal. Some suggest that irrigators seek greater certainty. I contend that irrigators understand and accept the variability risks and in any event "certainty" is a concept foreign to Australian farmers!

It seems to me that we really need to go back to basics. Were our rivers really unhealthy or are we confusing the natural results of extreme dryness with lack of health? If they really were (or are) unhealthy, how did this manifest itself and what were the underlying causes? Perhaps throwing water at the perceived problem is not the answer.

I note that the Australian Conservation Foundation describes the Murray Darling Basin as being at the point of eco-collapse, which really is complete nonsense. I have travelled over much of the Basin in recent months and the recovery following our flooding rains is a joy to behold.
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