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The Artesian Bore Pool at Lightning Ridge

Inflow into the Pilliga Artesian Bore Pool

The Great Artesian Basin

Location north western NSW (also in other states)

Source: www.environment.gov.au/water NSW Office of Water and Wikipedia

Link to Detailed Map

Artesian water is underground water confined and pressurised within a porous and permeable geological formation. Formations that store and transmit water are referred to as aquifers. When one of these aquifers is tapped by a bore, artesian water may flow naturally to the surface.

The Great Artesian Basin is one of the most important water resources in Australia. It underlies an area of 1.7 million square kilometres, approximately 22 per cent of the continent - including 12 per cent of New South Wales. The basin is the largest and deepest artesian basin in the world. The basin is 3,000 metres (9,800 ft) deep in places and is estimated to contain 64,900 cubic kilometres (15,600 cu mi) of groundwater.

Diagram showing The Great Artesian Basin location in NSW

It is the only source of reliable water for human activity and water-dependent ecosystems in much of the arid and semi-arid landscape overlaying the Basin in Queensland, New South Wales, South Australia and the Northern Territory.

Geology

The water of the Great Artesian Basin is held in several sandstone layers laid down by continental erosion of higher ground during the Triassic, Jurassic, and early Cretaceous periods. During a time when much of what is now inland Australia was below sea level, 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 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. The impermeable rocks confine the aquifers, causing the groundwater to become pressurised. In most areas the water is under sufficient pressure to provide a flowing source once it rises to the surface through artesian bores and natural springs.

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. 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. (Source Wikipedia)

It is estimated that more than 65 million gigalitres (GL) of water are stored in the Great Artesian Basin, at pressures of up to 1,300 kilopascals. The aquifers are recharged by infiltration of rainfall and leakage from streams into outcropping sandstone, mainly on the eastern margins of the Basin along the Great Dividing Range, and also along the western and south-western margins.

Groundwater flows under the influence of gravity and pressure from the recharge areas toward natural discharge springs in the west and southwest. This movement is slow, and in some parts the discharging water is up to 2 million years old. The predominantly fresh water emerges at temperatures which average 30 to 50°C and may be as high as 100°C (Source www.environment.gov.au/water NSW Office of Water and Wikipedia.

Experience the waters of the Great Artesian Basin at the NSW bore baths located at:

  • Lightning Ridge - Free entry
  • Pilliga Bore Baths - Free entry
  • Moree Hot Artesian Pool Complex - Entry Fee
  • Burren Junction - Free entry
  • Lightning Ridge Bore Baths - Free entry.

For excellent reference information on the Great Artesian Basin go to www.gabcc.org.au/


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