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The Great Artesian Basin: past, present and future
For millions of years, the Great Artesian Basin lay undisturbed—a vast subterranean reservoir, spreading under 1.7 million square kilometres (or about 22% of the Australian landmass including the areas which are now Queensland, New South Wales, South Australia and the Northern Territory). Its total capacity is estimated at around sixty-five billion megalitres—that’s enough to fill Sydney Harbour 120 000 times.
The Great Artesian Basin is essentially a series of water-bearing layers of sandstone, separated by impervious layers. The sandstone layers, or aquifers, are charged with water which falls as rain on Queensland’s mountainous coastal belt. This water flows west and south along the aquifers, returning to the surface as springs, hundreds, or even thousands of kilometres, from the source.
The flow of water is very a slow process, typically between one and five meters a year. Groundwater in the south-west of the Basin, the furthest point from where it first falls as rain, has been dated at nearly two million years old.
The Basin’s natural springs vary widely in type. There are open waterbodies with large rates of flow, and there are the lower flow types—the mud and peat ‘mound’ springs, or ‘bogga mosses’. The mound springs of the arid western areas played a significant role in Aboriginal culture. Travel routes followed the springs. Even then, resource management was important—the value of the water and what it could provide was understood, and respected. In good seasons, when rain was plentiful, the springs were little used—the land around them allowed to regenerate. When dry times occurred, the springs and their surrounding lands supported life.
The springs of the Great Artesian Basin were also an important part of life for the early drovers. They sustained life along the stock routes before the first bores were drilled. European discovery of groundwater in the Great Artesian Basin came in 1878, when a shallow bore near Bourke in New South Wales produced flowing water. Further discoveries followed quickly—in 1886, at Back Creek east of Barcaldine, and near Cunnamulla, the following year.
The seemingly endless supply of groundwater encouraged graziers to push westward. They dug thousands of kilometres of bore drains to carry the precious water to their prime sheep and cattle. The Great Artesian Basin underpinned the development of many rural communities, providing water for a host of activities. It must have seemed like an endless resource—clean, predominantly fresh water flooding up from underground. But by the early 1900s, water pressure was starting to decline, and there was recognition that the groundwater resource needed to be better managed.
In 1954 the Queensland government published a report of an investigation into the Great Artesian Basin and the problem of diminishing supplies. Essentially, the report represented the earliest form of water planning in the Basin and, quite possibly, Australia. It highlighted historical pressure decline occurring across the Basin and recommended controlling measures to ensure long-term supply from the resource. Now, the Great Artesian Basin Sustainability Initiative, or GABSI, is working to preserve this priceless resource for future generations by managing the water, controlling its use, and most importantly, by minimising wastage. A large proportion of the water drawn from the Basin is lost to seepage, and evaporation from bore drains.
This program, 'The Great Artesian Basin: past, present and future', tells the story of the Basin, and the work being done to preserve it as a reliable, renewable resource which will continue to support life in the heart of the driest inhabited continent on earth.
We hope you find it interesting, and informative.