Halve use of water to save Darling

Asa Wahlquist, Rural writer | September 08, 2007

THE extraction of water by irrigators on one of the Murray-Darling Basin's least developed tributaries would need to be halved by 2030 to ensure the Darling River received its minimum mandated flow.

The results of the CSIRO survey into the Warrego River, the first of a series on the basin, is alarming because it suggests that more developed river systems, like the Condamine-Balonne, will face serious problems.

By 2030, climate change and water use will see a 7 per cent reduction in the amount of water that flows out of the Warrego, in southwest Queensland, into the Darling.

Water extraction would have to be halved on the second-least developed river in the basin for the Warrego's water- sharing plan, which specifies 89 per cent of its flows should reach the Darling.

The Murray-Darling Basin Commission reports there is less than 12 gigalitres (billion litres) of private water storage built along the Warrego, compared with 1333GL on the Condamine-Balonne. In 2005-06, 25GL passed through Cunnamulla on the Warrego, while the total flow through St George, on the Balonne, was 123GL.

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Streamflow (Recent Trends - North America) -- Summary

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In a perceptive study of 20th-century streamflow trends, Lins and Slack (1999) state that "floods and droughts cause more damage annually in the United States than any other natural disaster," and that "there is an increasing trend in both flood damage and drought vulnerability." However, they note that "most of the flood damage increase stems from continuing urban and suburban development on floodplains," and that "drought vulnerability increase is from development in regions of lower renewable water supplies." Nevertheless, there is a widespread perception, as the two researchers describe it, that "extreme hydrologic events are increasing in frequency and/or magnitude." In particular, they cite the Mississippi floods of 1993, the widespread United States flooding of 1997 in the West, Upper Midwest and Ohio Valley, as well as the droughts of 1988 and 1995-96, as giving "rise to speculation that floods and droughts are increasing, possibly in response to greenhouse warming," which is a concept that is widely promulgated by the world's climate alarmists. Consequently, in this brief Summary we review what has been learned about this contention as it pertains to North America.

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