Great Artesian Basin
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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 ...
, is the largest and deepest
artesian basin An artesian aquifer is a confined aquifer containing groundwater under positive pressure. An artesian aquifer has trapped water, surrounded by layers of impermeable rock or clay, which apply positive pressure to the water contained within th ...
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 containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
through much of inland Australia. The Basin underlies 22% of the continent, including the states and territories of
Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...
(most of), the
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...
(the south-east corner of),
South Australia South Australia (commonly abbreviated as SA) is a 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 Australia's states and territories ...
(the north-east part of), and
New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...
(northern part of). The basin is deep in places and is estimated to contain of
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
. 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 East or Orient is one of the four cardinal directions or points of the compass. It is the opposite direction from west and is the direction from which the Sun rises on the Earth. Etymology As in other languages, the word is formed from the f ...
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 and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...
,
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
, and early
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
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 surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
, 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 ''Uplifted'' is the second studio album by Nigerian singer Flavour N'abania. It was released on July 20, 2010, by Obaino Music and 2nite Entertainment. The album features guest appearances from Jay Dey, Oloye, Stormrex, Waga Gee, Asemstone, M-Jay, ...
when the
Great Dividing Range The Great Dividing Range, also known as the East Australian Cordillera or the Eastern Highlands, is a cordillera system in eastern Australia consisting of an expansive collection of mountain ranges, plateaus and rolling hills, that runs rough ...
formed. The other side was created from the
landform A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, ...
s of the
Central Eastern Lowlands Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...
and the
Great Western Plateau The Western Plateau is Australia's largest drainage division and is composed predominantly of the remains of the ancient rock shield of Gondwana. It covers two thirds of the continent; of arid land, including large parts of Western Australia, ...
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 Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...
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. 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 Dalhousie Springs, also known as Witjira-Dalhousie Springs, is a group of over 60 natural artesian springs located in Witjira National Park on the western fringe of the Simpson Desert, 180 kilometres northeast of Oodnadatta in northern South A ...
. These springs sustained a variety of endemic invertebrates, such as
molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil sp ...
, 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 Australia ICOMOS is a peak cultural heritage conservation body in Australia. It is a branch of the United Nations-sponsored International Council on Monuments and Sites (ICOMOS), a non-government professional organisation promoting expertise in ...
'', 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 Australian Overland Telegraph Line was a telegraphy system to send messages over long distances using cables and electric signals. It spanned between Darwin, in what is now the Northern Territory of Australia, and Adelaide, the capital o ...
. The Great Artesian Basin became an important water supply for
cattle station In Australia and New Zealand, a cattle station is a large farm ( station is equivalent to the American ranch), the main activity of which is the rearing of cattle. The owner of a cattle station is called a '' grazier''. The largest cattle stati ...
s,
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
, and
livestock Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...
and domestic purposes, and is a vital life line for rural Australia. To tap it,
borehole A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petro ...
s are drilled down to a suitable rock layer, and the pressure of the water often forces it up without the need for
pump A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy. Pumps can be classified into three major groups according to the method they u ...
s. 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 produced flowing water. There were similar discoveries in 1886 at Back Creek east of Barcaldine, and in 1887 near
Cunnamulla Cunnamulla () is a town and a locality in the Shire of Paroo, Queensland, Australia. It is south of Charleville, and approximately west of the state capital, Brisbane. In the , Cunnamulla had a population of 1,140 people. Geography 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 power : ''For the physics concept, see .'' Mechanical power is a medical term which is a measure of the amount of energy imparted to a patient by a mechanical ventilator. While in many cases mechanical ventilation is a life-saving or life-preserving in ...
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 The Olympic Dam mine is a large poly-metallic underground mine located in South Australia, NNW of Adelaide. It is the fourth largest copper deposit and the largest known single deposit of uranium in the world. Copper is the largest contributor ...
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 bore, for a
geothermal power Geothermal power is electrical power generated from geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 2 ...
station at
Birdsville Birdsville is a rural town and locality in the Shire of Diamantina, Queensland, Australia. In the the locality of Birdsville had a population of 110 people. It is a popular tourist destination with many people using it as a starting point acro ...
. 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
coal seam gas Coalbed methane (CBM or coal-bed methane), coalbed gas, coal seam gas (CSG), or coal-mine methane (CMM) is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in United States, Canada, Au ...
(CSG) drilling and hydraulic fracturing. In 2011, ABC TV's public affairs program ''
Four Corners The Four Corners is a region of the Southwestern United States consisting of the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona, and northwestern corner of New Mexico. The Four Corners area ...
'' revealed that significant concerns were being expressed about depletion and chemical damage to the Basin as a result of
coal seam gas Coalbed methane (CBM or coal-bed methane), coalbed gas, coal seam gas (CSG), or coal-mine methane (CMM) is a form of natural gas extracted from coal beds. In recent decades it has become an important source of energy in United States, Canada, Au ...
extraction. In one incident, reported in the program, the Queensland Gas Company (QGC) " 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. 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 The geology of Australia includes virtually all known rock types, spanning a geological time period of over 3.8 billion years, including some of the oldest rocks on earth. Australia is a continent situated on the Indo-Australian Plate. Compon ...
*
Guarani Aquifer The Guarani Aquifer, located beneath the surface of Argentina, Brazil, Paraguay, and Uruguay, is the second largest known aquifer system in the world and is an important source of fresh water. Named after the Guarani people, it covers , with a v ...


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
Basins Basin may refer to: Geography and geology * Depression (geology) ** Back-arc basin, a submarine feature associated with island arcs and subduction zones ** Debris basin, designed to prevent damage from debris flow ** Drainage basin (hydrology), a ...
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