The Great Artesian Basin provides the only reliable source of freshwater

Freshwater

Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...

 through much of inland Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The basin is the largest and deepest artesian basin

Artesian aquifer

An artesian aquifer is a confined aquifer containing groundwater under positive pressure. This causes the water level in a well to rise to a point where hydrostatic equilibrium has been reached. This type of well is called an artesian well...

 in the world, stretching over a total of 1711000 square kilometres (660,620.8 sq mi), with temperatures measured ranging from 30°C to 100°C. It underlies 23% of the continent, including most of Queensland

Queensland

Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

, the south-east corner of the Northern Territory

Northern Territory

The 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 Australia

South Australia

South 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.South Australia shares borders with all of the mainland...

, and northern New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

. The basin is 3000 metres (9,842.5 ft) deep in places and is estimated to contain 64900 cubic kilometres (15,570.3 cu mi) of groundwater

Groundwater

Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock 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 rock...

. 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 Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . 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...

, Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, 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 Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , 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 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 level

Sea level

Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

, 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 uplifted

Tectonic uplift

Tectonic 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 Range

Great Dividing Range

The Great Dividing Range, or the Eastern Highlands, is Australia's most substantial mountain range and the third 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 landform

Landform

A landform or physical feature in the earth sciences and geology sub-fields, 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 sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

 grains, flowing at a rate of one to five metres per year.

Discharge water eventually exits through a number of springs

Spring (hydrosphere)

A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...

 and seeps

Seep (hydrology)

A Seep is a moist or wet place where water, usually groundwater, reaches the earth's surface from an underground aquifer.-Description:Seeps are usually not of sufficient volume to be flowing beyond their above-ground location. They are part of the limnology-geomorphology system...

, 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 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 Line

Australian Overland Telegraph Line

The 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 station

Cattle station

Cattle 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, irrigation

Irrigation

Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

, and livestock

Livestock

Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...

 and domestic usage, and is a vital life line for rural Australia. To tap it, water well

Water well

A 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 trash 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 pump

Pump

A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

ing.

The discovery and use of water held underground in the Great Artesian Basin opened up thousands of square miles of country away from rivers 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

Bourke, New South Wales

-Transportation:Bourke can be reached by the Mitchell Highway, with additional sealed roads from town to the north , east and south . The town is also served by Bourke Airport and has Countrylink bus service to other regional centres, like Dubbo...

 produced flowing water. There were similar discoveries in 1886 at Back Creek east of Barcaldine

Barcaldine, Queensland

Barcaldine is a small town in Western Queensland, Australia, approximately by road west of the city of Rockhampton. The town is situated on Lagoon Creek, which flows into the Alice River approximately five kilometres south of the Barcaldine. This is the administrative centre of the Barcaldine...

, and in 1887 near Cunnamulla

Cunnamulla, Queensland

Cunnamulla 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....

.

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 2000 megalitre of water per day, but today the total output has dropped to 1500 megalitre per day. This included just under 2000 freely flowing bores and more than 9000 that required mechanical power

Mechanical advantage

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...

 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 1.2 km (0.745647283979768 mi) deep bore for a geothermal power

Geothermal power

Geothermal energy is thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. Earth's geothermal energy originates from the original formation of the planet and from radioactive decay of minerals...

 station at Birdsville

Birdsville, Queensland

-External links:*...

. The heated water is 98 °C (208 °F) and provides 25% of the town's needs. Ergon Energy

Ergon (Australia)

Ergon is a corporation owned by the Government of Queensland, Australia. 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 to other sites which discuss the Basin can be accessed from there.

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.

Potential depletion and pollution due to coal seam gas extraction

On 21 February 2011, ABC Four Corners revealed that significant concerns were being expressed about depletion and chemical damage to the Great Artesian Basin as a result of coal seam gas 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, in the process releasing 130 litres of a potentially toxic chemical into the Great Artesian Basin. QGC admitted the incident, but did not report it to authorities for 13 months. The safety data sheet QGC had submitted for the fracking chemical was derived from the United States, incomplete and 10 years out of date Over 30 chemicals may be used in the process of 'fracking' and their long term impact on aquifers and the agriculture and people supported by them is unknown.

External links

• A New Understanding of the Groundwater Resources of the Great Artesian Basin, L.A. Endersbee, Australian Academy of Technological Sciences and Engineering
• The Great Artesian Basin, Queensland Department of Natural Resources and Water
• Ancient water source vital for Australia, ScienceDaily
• http://www.gabcc.org.au/ Great Artesian Basin Coordinating Committee - information and resources relating to the Great Artesian Basin
• Water Down Under - The Great Artesian Basin Story, 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