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The Great Artesian Basin (GAB), located in
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Australia
, is the largest and deepest artesian basin in the world, stretching over , with measured water temperatures ranging from . The basin provides the only source of
fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in ...

fresh water
through much of inland Australia. The Basin underlies 22% of the continent, including the states and territories of
Queensland Queensland ( ) is a state situated in northeastern Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the ...

Queensland
(most of), the
Northern Territory The Northern Territory (NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, ...
(the south-east corner of),
South Australia South Australia (abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Austral ...

South Australia
(the north-east part of), and
New South Wales New South Wales (abbreviated as NSW) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
(northern part of). The basin is deep in places and is estimated to contain of
groundwater Groundwater is the water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known form ...

groundwater
. The Great Artesian Basin Coordinating Committee (GABCC) GABCC website
coordinates activity between the various levels of government and community organisations.


Physiography

This area is one of the distinct physiographic provinces of the larger East Australian Basins division, and includes the smaller Wilcannia Threshold physiographic section.


Geology

The water of the Great Artesian Basin is held in a sandstone layer laid down by continental erosion of higher ground during the
Triassic The Triassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...

Triassic
,
Jurassic The Jurassic ( ) is a geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology, paleontologists, and other earth ...
, and early
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
periods. During a time when much of what is now inland Australia was below
sea level Mean sea level (MSL) (often shortened to sea level) is an average In colloquial, ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of the numbers divided by how many numbers are in th ...

sea level
, the sandstone was then covered by a layer of marine sedimentary rock shortly afterward, which formed a confining layer, thus trapping water in the sandstone aquifer. The eastern edge of the basin was uplifted when the
Great Dividing Range The Great Dividing Range, also known as the East Australian Cordillera or the Eastern Highlands, is a cordillera A cordillera is an extensive chain of mountains A mountain is an elevated portion of the Earth's crust 350px, Plates in ...

Great Dividing Range
formed. The other side was created from the
landform A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws ...

landform
s 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 toward 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 spring (hydrosphere), springs and Seep (hydrology), seeps, mostly in the southern part of the basin. The age of the groundwater, determined by carbon-14 and chlorine-36 measurements combined with hydraulic modelling, ranges from several thousand years for the recharge areas in the north to nearly 2 million years in the south-western discharge zones.


Water source

Prior to European occupation, waters of the Great Artesian Basin (GAB) discharged through mound springs, many in arid South Australia, such as Witjira-Dalhousie Springs. These springs sustained a variety of endemic invertebrates, such as mollusca, molluscs, and supported extensive Aboriginal communities and trade routes.Harris, Colin (2002)
Culture and geography: South Australia’s mound springs as trade and communication routes
, ''Historic Environment'', 16 (2), 8–11. .
After the arrival of Europeans, the springs facilitated exploration, and allowed the provision of faster communications between south-eastern Australia and Europe, via the Australian Overland Telegraph Line. The Great Artesian Basin became an important water supply for cattle stations, irrigation, and livestock and domestic purposes, and is a vital life line for rural Australia. To tap it, boreholes are drilled down to a suitable rock layer, and the pressure of the water often forces it up without the need for pumps. The discovery and use of the water in the Great Artesian Basin allowed the settlement of thousands of square kilometres of country away from rivers in inland New South Wales, Queensland, and South Australia, that would otherwise have been unavailable for pastoral activities. European discovery of the basin dates from 1878 when a shallow bore near Bourke, New South Wales, Bourke produced flowing water. There were similar discoveries in 1886 at Back Creek east of Barcaldine, Queensland, Barcaldine, and in 1887 near Cunnamulla, Queensland, Cunnamulla. In essence, water extraction from the GAB is a mining operation, with recharge much less than current extraction rates. In 1915, there were 1,500 bores providing of water per day, but today the total output has dropped to per day. This included just under 2000 freely-flowing bores and more than 9000 that required mechanical advantage, mechanical power to bring water to the surface. Many bores are unregulated or abandoned, resulting in considerable water wastage. These problems have existed for many decades, and in January 2007 the Australian Commonwealth Government announced additional funding in an attempt to bring them under control. However, many of the mound springs referred to above have dried up due to a drop in water pressure, probably resulting in extinction of several invertebrate species. The Olympic Dam mine in South Australia is permitted to extract up to of water daily from the Great Artesian Basin under the ''Roxby Downs (Indenture Ratification) Act 1982''. The underground copper and uranium mine commenced operations in 1988 and is expected to continue operating until approximately 2060. In addition, the Basin provides water, via a -deep bore, for a geothermal power station at Birdsville, Queensland, Birdsville. Water emerges from the bore at and provides 25% of the town's electricity needs. After being cooled, the water is also the source of the town's drinking water.


Whole of Basin management

As the Great Artesian Basin underlies parts of Queensland, New South Wales, South Australia and the Northern Territory, which each operate under different legislative frameworks, policies and resource management approaches, a coordinated "whole-of-Basin" approach to the management of this important natural resource is required. The Great Artesian Basin Coordinating Committee (GABCC) provides advice from community organisations and agencies to State, Territory and Australian Government Ministers on efficient, effective and sustainable whole-of-Basin resource management and to coordinate activity between stakeholders. Membership of the Committee comprises all State, Territory, and Australian Government agencies with responsibilities for management of parts of the Great Artesian Basin, community representatives nominated by agencies; and sector representatives.


Environmental concerns

There is a strong debate surrounding Coalbed methane, coal seam gas (CSG) drilling and hydraulic fracturing. In 2011, ABC1, ABC TV's public affairs program ''Four Corners (Australian TV program), Four Corners'' revealed that significant concerns were being expressed about depletion and chemical damage to the Basin as a result of coal seam gas extraction. In one incident, reported in the program, the Queensland Gas Company (QGC) "Hydraulic fracturing, fracked" its Myrtle 3 well connecting the Springbok aquifer to the coal seam below (the Walloon Coal Measures) in 2009. A local farmer was concerned that the process might have released of a potentially toxic chemical into the Basin. QGC admitted the incident, but "did not alert authorities or nearby water users about the problem until thirteen months after the incident". The safety data sheet QGC had submitted for the hydraulic fracturing chemical was derived from the United States, incomplete and ten years out of date. Over thirty chemicals may be used in the process of hydraulic fracturing and their long-term impact on aquifers, agriculture and people supported by them has been quantifiable and verified for quite some time, yet largely covered up by interested parties. Lead, aluminium, arsenic, barium, boron, nickel and uranium have all been found beyond recommended levels in the groundwater contaminated by CSG. Instances of groundwater being contaminated and by extension poisoning the ecosystems sustained by the availability of groundwater have been widely documented, and are an exacerbating factor in regards to the population's capability to cope with drought through usage of groundwater sources in Australia.


See also

*Geology of Australia *Guarani Aquifer


References


External links


Ancient water source vital for Australia
ScienceDaily
Great Artesian Basin Coordinating Committee website
- information and resources relating to the Great Artesian Basin

Video production by Anvil Media on behalf of the Great Artesian Basin Coordinating Committee (GABCC), 2008, Australian Government Department of Sustainability, Environment, Water, Population and Communities {{Authority control Drainage basins of Australia Aquifers in Australia Endorheic basins of Australia Landforms of New South Wales Landforms of the Northern Territory Landforms of Queensland Landforms of South Australia Geology of Australia, Basins Regions of Australia Regions of the Northern Territory Regions of New South Wales Regions of Queensland Regions of South Australia Lake Eyre basin Physiographic provinces