IT is assumed in the draft Murray Darling Basin Plan that the more water in the Murray River and in particular the more water moving down the river to South Australia, the healthier the environment. But what’s the philosophical basis for such an assumption?
As I wrote in my column for The Land newspaper this week:
If the current water reform process is truly about giving back to the environment, then we should be thinking back to a period before rivers and creeks became constricted by sheets of water running off compacted soils, before swamps were diverted, before river de-snagging and before the blasting of rock bars for paddle steamers.
As historian Bill Gammage notes in The Biggest Estate on Earth: How Aborigines Made Australia, back in the dreamtime shallow streams and overflows flushed more of Australia, filling billabongs, swamps and holes, and recharging springs and soaks.
That was a time when the health of a landscape was measured less by how much water was in a river, and more by how many kangaroos it could support.
In 1901 James Cotton, a Cobar pioneer, wrote that before the district was stocked with sheep and cattle it was covered with a heavy growth of natural grasses and that the ground was soft, spongy and very absorbent.
Overstocking was a problem throughout the Murray Darling Basin particularly during the late 1800s resulting in significant land and water degradation. Overstocking transformed soils in many districts from soft and spongy to hard clay that, instead of absorbing water, caused the rain to run off in sheets as fast as it fell – to again paraphrase Mr Cotton.
In the past one hundred years there has been a gradual improvement in land management. Stocking rates have fallen, some native grasses are returning and there has been a move to minimum tillage conservation farming practices. This has resulted in a general improvement in soil structure.
The ground may not be as soft, spongy and very absorbent as it once was, but there is no doubt that when the rain now falls on the Murray Darling, much less water runs off into adjacent rivers and streams than it did one hundred years ago. This must have implications for the amount of water flowing to South Australia.
Indeed a truly healthier Murray Darling Basin would mean less water for South Australia.
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My entire column can be read on page 9 of The Land – in newsagents now.
Bill Gammage, The Biggest Estate on Earth: How Aborigines Made Australia. Allen & Unwin, 2011. I got my copy from Dymock’s in Sydney for $49.99; and bought another as a Christmas present.
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.