The
Great Artesian Basin provides the only reliable source of
freshwaterFreshwater is naturally occurring water on the surface such as bogs, ponds, lakes, rivers and streams, and underground in aquifers and underground rivers. Freshwater is characterized by having low concentrations of dissolved salts...
through much of inland
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
. The basin is the largest and deepest
artesian basinAn artesian aquifer is a confined aquifer containing groundwater that will flow upward through a well, called an artesian well, without the need for pumping...
in the world, covering a total of , with temperatures measured ranging from 30°C to 100°C. It underlies 23% of the continent, including most of
QueenslandQueensland is a state of Australia that occupies the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, the south-east corner of the
Northern TerritoryThe Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
, the north-east part of
South AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories....
, and northern
New South WalesNew South Wales is Australia's most populous state, located in the south-east of the country, north of Victoria, south of Queensland and east of South Australia...
. The basin is deep in places and is estimated to contain of
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...
.
The
Great Artesian Basin provides the only reliable source of
freshwaterFreshwater is naturally occurring water on the surface such as bogs, ponds, lakes, rivers and streams, and underground in aquifers and underground rivers. Freshwater is characterized by having low concentrations of dissolved salts...
through much of inland
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
. The basin is the largest and deepest
artesian basinAn artesian aquifer is a confined aquifer containing groundwater that will flow upward through a well, called an artesian well, without the need for pumping...
in the world, covering a total of , with temperatures measured ranging from 30°C to 100°C. It underlies 23% of the continent, including most of
QueenslandQueensland is a state of Australia that occupies the north-eastern section of the mainland continent. It is bordered by the Northern Territory to the west, South Australia to the south-west and New South Wales to the south. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, the south-east corner of the
Northern TerritoryThe Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
, the north-east part of
South AustraliaSouth Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories....
, and northern
New South WalesNew South Wales is Australia's most populous state, located in the south-east of the country, north of Victoria, south of Queensland and east of South Australia...
. The basin is deep in places and is estimated to contain of
groundwaterGroundwater is water located beneath the ground surface in soil pore spaces and in the fractures of lithologic formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in...
. The Great Artesian Basin Coordinating Committee (GABCC) 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 GAB is held in a sandstone layer laid down by continental erosion of higher ground during the
TriassicThe Triassic is a geologic period and system that extends from about 251 to 199 Ma . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
,
JurassicThe Jurassic is a geologic period and system that extends from about Ma to Ma, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the "Age of Reptiles". The start of the period is marked by...
, and early
CretaceousThe Cretaceous , Latin language for "chalky", usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago . In the geologic timescale, the Cretaceous follows on the Jurassic period and is followed by the Paleogene period of the...
periods. During a time when much of what is now inland Australia was below
sea levelMean sea level is the average height of the ocean's surface ; used as a standard in reckoning land elevation.- Measurement :...
, the sandstone was then covered by a layer of marine sedimentary rock shortly afterwards, which formed a confining layer - thus trapping water in the sandstone aquifer. The eastern edge of the basin was
upliftedTectonic uplift is a geological process most often caused by plate tectonics which increases elevation. The opposite of uplift is subsidence, which results in a decrease in elevation. Uplift may be orogenic or isostatic.-Orogenic uplift:...
when the
Great Dividing RangeThe Great Dividing Range, or the Eastern Highlands, is Australia's most substantial mountain range and the fourth longest in the world. The range stretches more than 3,500 km from Dauan Island off the northeastern tip of Queensland, running the entire length of the eastern coastline through...
formed. The other side was created from the
landformIn the earth sciences and geology sub-fields, a landform or physical feature comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...
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 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
sandSand is a naturally occurring granular material composed of finely divided rock and mineral particles.As the term is used by geologists, sand particles range in diameter from 0.0625 to 2 millimeters. An individual particle in this range size is termed a sand grain...
grains, flowing at a rate of one to five metres per year.
Discharge water eventually exits through a number of
springsA spring is any natural occurrence where water flows on to the surface of the earth from below the surface, and is thus where the aquifer surface meets the ground surface.- Formation :...
and
seepsA seep is a wet place where a liquid, usually groundwater, has oozed from the ground to the surface. Seeps are usually not flowing, with the liquid sourced only from underground. It is often used in environmental sciences to define an exfiltration zone where contaminated water, e.g., from waste...
, 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 EyreLake Eyre is the lowest point in Australia, at approximately below sea level and, on the rare occasions that it fills, it is the largest lake in Australia...
area.
Water source
Prior to European occupation, waters of the GAB discharged through mound springs, many in arid South Australia. These springs supported a variety of endemic invertebrates (molluscs, for example), and supported extensive Aboriginal communities and trade routes. After the arrival of Europeans, they enabled early exploration and faster communications between southeastern Australia and Europe via the
Australian Overland Telegraph LineThe Australian Overland Telegraph Line was a 3200 km telegraph line that connected Darwin with Port Augusta in South Australia. Completed in 1872 the Overland Telegraph Line allowed fast communication between Australia and the rest of the world. An additional section was added in 1877 with the...
. The Great Artesian Basin became an important water supply for
cattle stationCattle station is an Australian term for a large farm , whose main activity is the rearing of cattle. In Australia, the owner of a cattle station is called a grazier...
s,
irrigationIrrigation is an artificial application of water to the soil. It is usually used to assist in growing crops in dry areas and during periods of inadequate rainfall...
, and
livestockLivestock are one or more domesticated animals raised in an agricultural setting to produce commodities such as food or fiber, or labor...
and domestic usage, and is a vital life line for rural Australia. To tap it,
water wellA water well is an excavation or structure created in the ground by digging, driving, boring or drilling to access groundwater in underground aquifers. The well water is drawn by an electric submersible pump, a vertical turbine pump, a handpump or a mechanical pump...
s are drilled down to a suitable rock layer, where the pressure of the water forces it up, mostly without
pumpA pump is a device used to move fluids, such as gases, liquids or slurries. A pump displaces a volume by physical or mechanical action. One common misconception about pumps is the thought that they create pressure. Pumps alone do not create pressure; they only displace fluid, causing a flow. ...
ing.
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 WalesBourke is a town and Local Government Area in the north of New South Wales, Australia. The town is located approximately 800 kilometres north-west of Sydney, on the south bank of the Darling River...
produced flowing water. There were similar discoveries in 1886 at Back Creek east of
Barcaldine, QueenslandBarcaldine is a small town and Local Government Area located in Western Queensland, Australia, approximately by road west of the city of Rockhampton. The town is the administrative centre of the Barcaldine region. Town population is around 1900. Major industries are wool and grazing...
, and in 1887 near
Cunnamulla, QueenslandCunnamulla is a small town that lies on the Warrego River in south west Queensland, Australia, south of Charleville, and approximately west of the state capital, Brisbane.-Location:...
.
Water extraction from the GAB is essentially 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 powerIn physics and engineering, mechanical advantage is the factor by which a mechanism multiplies the force or torque put into it. Generally, the mechanical advantage is calculated as follows:or more simply:...
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. Unfortunately, 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.
Additionally, the basin has provided water via a deep bore for a
geothermal powerGeothermal power is power extracted from heat stored in the earth. This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface...
station at
BirdsvilleBirdsville is a small town located in the Channel Country of western Queensland, Australia. The town is located 1590 kilometres west of the state capital, Brisbane, and 720 kilometres south of the city of Mount Isa. Birdsville is situated on the edge of the Simpson Desert, and the climate is very...
. The heated water is 98 °C (208 °F) and provides 25% of the town's needs.
Ergon EnergyErgon is a corporation owned by the Government of Queensland. It supplies electricity to Queenslanders outside the metropolitan southeast through a distribution network and retail activities....
is expanding the 80 kW plant to completely meet Birdville's electricity requirements .
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. The primary role of the Committee is to provide advice to State, Territory and Australian Government Ministers on efficient, effective and sustainable whole-of-Basin resource management and to coordinate activity between stakeholders.
The GABCC website provides up to date information and links regarding the Great Artesian Basin and can be accessed through their website.
Current scientific thinking
A comprehensive background to the Great Artesian Basin, including an overview of the nature of the Basin, the extraction of water and the impacts of that extraction, can be found in the Great Artesian Basin Resource Study, developed by the GABCC to support the Great Artesian Basin Strategic Management Plan.
External links