Great Artesian Basin

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The Great Artesian Basin provides the only reliable source of water through much of inland Australia. The basin is the largest and deepest artesian basin in the world. It underlies 23% of the continent, including most of Queensland, the south-east corner of the Northern Territory, the north-east part of South Australia, and northern New South Wales. The basin is 3000 metres (10,000 ft) deep in places and has been estimated to contain between 9 and 65 cubic kilometres (7 to 52 billion acre-feet) of groundwater.

The aquifers that make up the Great Artesian Basin are composed of layers of quartzose sandstone laid down by continental erosion of higher ground during the Triassic, Jurassic, and early Cretaceous periods, and covered by a layer of marine sedimentary rock laid down shortly afterwards, during a time when much of what is now inland Australia was below sea level. The eastern edge of the basin was uplifted when the Great Dividing Range formed. The other side was created from the landforms of the Central Eastern Lowlands and the Great Western Plateau to the west.

Most recharge water enters the rock formations from relatively high ground near the eastern edge of the basin (in Queensland and New South Wales) and very gradually flows towards the south and west. (A much smaller amount enters along the western margin in arid central Australia, flowing to the south and east.) Because the sandstones are permeable, water gradually makes its way through the pores between the sand grains, flowing at a rate of one to five metres per year.

Discharge water eventually exits through a number of springs and seeps, mostly in the southern part of the basin. It takes up to two million years for water to travel to the springs in the Lake Eyre area.

It is the source of most of the water used in these areas. The basin is an important source of water for cattle raising. Whilst unsuitable for irrigation, it is adequate for stock and domestic usage (with treatment) and is thus vital to human activity. To tap it, bores are drilled down to a suitable rock layer, where the pressure of the water forces it up, mostly without pumping. Additionally, water at 98 °C (208 °F) from the basin is used to power a small 150 kW generator in Birdsville.

In 1983 there were close to 18 000 bores providing 1575 million litres of water. This included just under 2000 freely flowing bores and more than 9000 that required mechanical power to bring water to the surface.

[edit] Alternative view of water recharge

L. A. Endersbee promotes an alternative view of the recharge mechanism of the Great Australian Basin, suggesting that the orthodox view that the water content is continuously replenished by slow seepage from the strata outcrops in the uplands to the east, is incorrect. He suggests that the water is derived from deep within the Earth, and that it was part of the original composition of the Earth.[1][2]

[edit] External links

• [3] L.A. Endersbee, "A New Understanding of the Groundwater Resources of the Great Artesian Basin", Australian Acedemy of Technological Sciences and Engineering