Garnaut Report - Oz Urban Water Systems Face Chronic Stress - Irrigated Farming To Fall 50% By 2050

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THE Garnaut report, the Impacts of Climate Change in Australia, paints a grim picture. Without mitigation, it says, within the next two decades urban water supplies will be stressed, and agriculture will be affected. By mid-century irrigated agriculture in the Murray-Darling Basin will be halved.

If this sounds familiar, it is because this is already happening. Every mainland state capital city, and most inland regional towns and cities are on water restrictions. The urban water industry has embarked on a $30 billion investment program in new water sources, in desalination, water recycling and infrastructure. Executive director of Water Services Association of Australia, Ross Young, says 2008's record capital works spend of $2 billion, double the previous peak, was prompted by climate change. Across the southern Murray-Darling Basin, river inflows have been falling well below long-term averages. Irrigation has effectively been halved.

Chair of Natural Resource Science at the University of Adelaide, Wayne Meyer, says the past three years offer a good insight into what future irrigation in the basin will look like, when there is forecast to be 30 to 50 per cent less water. He points out 2001/02 was the last year irrigators received full allocations. That year 11,000 gigalitres or billion litres (the amount of water in a square kilometre filled to a depth of one metre) was diverted. "In 2006/07 there was reasonably strict allocations and we took out about 4767 GL," Professor Meyer says. Permanent plantings -- fruit and nut trees and grapevines -- received around 80 per cent of their allocations, while general security irrigators who grow pasture for livestock, grain crops, rice, cotton, sorghum and hay, received 40 to 45 per cent of their water. "That is the kind of thing you probably have got to be planning for and starting to work towards, if we are going to be able to adapt into this future," he says.

Most people with perennial plantings can adapt to an 80 per cent allocation, and get reasonable production. "But with 40 per cent for pastures, you really have to change what you do and the way in which you do it," he says.

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http://www.theaustralian.news.com.au/story/0,25197,24546508-11949,00.html