Smarter Irrigation in Drier Century: With Global Climate Models Indicating a Further 20 per Cent Decline in Rainfall across Southeastern Australia by 2030, Irrigated Agriculture, Particularly in the Southern Murray-Darling Basin, Is Suddenly Facing an Uncertain Future. Now That the New COAG National Water Plan Is Signed, How Might Our Irrigation Systems Be Adapted for the 21st Century? Graeme O'Neill Provides Some Perspective
O'Neill, Graeme, Ecos
Along the Murray River, from Lake Hume at Albury to the South Australian border, irrigators experienced an annus horribilis in 2007. By August, the worst drought since European settlement had reduced water storages on the Murray and Goulburn rivers to the lowest levels on record. Relative to long-term averages, rainfall in this heartland of irrigated horticulture had already declined by about 20 per cent.
Water authorities imposed draconian water restrictions on irrigated dairy farms, vineyards and orchards, and on Murray River cities and towns that had hardly experienced few more serious water shortages in over a century.
But despite continuing drought and the concerns of irrigators, Wayne Meyer, Professor of Natural Resource Science at the University of Adelaide, believes the future of irrigation in Australia is not in doubt. He predicts production from irrigated agriculture will increase in value in years to come--climate change or not.
'Australia is in a unique position,' Professor Meyer said. 'We have a full range of areas suitable for irrigation, from temperate to tropical.
'We will see a consolidation of irrigation in its traditional areas in south-eastern Australia, where there are already concerns about the impact of irrigated dairy farms on salinity.
'The value of water will rise, so dairy farmers in northern Victoria and the Goulburn Valley will find it worthwhile to trade it out for urban and industrial use. A relatively small amount will be taken out of the system for Victoria's proposed North-South Pipeline to supply metropolitan Melbourne.
'We'll see growers of fruit, vegetables, vines and tree crops such as almonds take more control of their water. The trend to redevelopment and relocation is already underway, despite some institutional barriers.
'But', he points out, 'it makes sense to say that a certain area is not a good place to irrigate because of supply problems, or the potential impact on groundwaters.'
The man considered Australia's leading expert on water policy and management, the late Professor Peter Cullen, who was to have been interviewed for this article before his untimely death in March, observed recently, 'All the new irrigation action is on new greenfield sites, because layout is easier than refurbishing old, inefficient layouts.'
Professor Meyer agrees. 'We need to discourage further development in problem areas, and encourage relocation. With the changing climate, we should be phasing out irrigation in higher-risk areas with problem soils, and moving it back from the rivers so that high-saline groundwater discharges don't exacerbate water salinity.'
This has already occurred in the Sunraysia irrigation area around Mildura, where real estate values closer to the river now exceed the value of production.
Professor Meyer says the changing emphasis means there is likely to be some expansion of irrigated fruit, vegetables and high-value medicinal seeds in new areas, such as Tasmania.
Meanwhile, the perennial dream of irrigating Australia's tropical north remains alive, but the reality is that the region's lack of deep, fertile alluvial soils constrains large-scale expansion. Professor Meyer says a mosaic of small, isolated irrigation developments is the likely future of irrigation in the tropics.
Other, lower-lying areas with potentially suitable soils flood during the Wet, so are unsuitable for irrigation, as rice growers on the Humpty Doo plains south of Darwin discovered.
'I've been to Western Australia's Ord River scheme a couple of times, and they've certainly got plenty of water" Professor Meyer said. 'But there are high risks involved in Ord stages 2 and 3 expansion, because much of the land is only two or three metres above sea level--they're almost tidal areas. …