Great Artesian Basin
From Wikipedia, the free encyclopedia
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 is estimated to contain 64,900 cubic kilometres of groundwater.[1] The Great Artesian Basin Coordinating Committee (GABCC) [1] coordinates activity between the various levels of government and community organisations.
Contents |
[edit] Geology
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.
[edit] Water source
It is the source of most of the water used in these areas. The basin is an important water suppyly 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.
The discovery and use of water held underground in the Great Artesian Basin opened up thousands of square miles of country in inland New South Wales, Queensland and South Australia, previously unavailable for pastoral activities. European discovery of the basin dates from 1878 when a shallow bore near Bourke, New South Wales produced flowing water. There were similar discoveries in 1886 at Back Creek east of Barcaldine, Queensland, and in 1887 near Cunnamulla, Queensland.[2]
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.
Additionally, the basin has provided water via a 1.2 km deep bore for a Geothermal power station at Birdsville. The heated water is 98 °C (208 °F) and provides 25% of the towns needs. Ergon Energy is expanding the 80 kW plant to completely meet Birdville's electricity requirements[citation needed].
[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.[2][3][4]
[edit] External links
- [5] L.A. Endersbee, "A New Understanding of the Groundwater Resources of the Great Artesian Basin", Australian Academy of Technological Sciences and Engineering
[edit] References
- ^ The Great Artesian Basin (PDF). Facts: Water Series. Queensland Department of Natural Resources and Water. Retrieved on January 3, 2007.
- ^ Nicol, Sally (2005). The Great Artesian Basin: past, present and future. Water management. The State of Queensland (Department of Natural Resources and Water). Retrieved on March 2, 2007.
