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Great Artesian Basin

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The Great Artesian Basin is the largest and deepest artesian basin on Earth. It covers approximately 22% of the Australian continent. This massive underground system includes most of Queensland and the south-east corner of the Northern Territory. It also extends into north-eastern South Australia and northern New South Wales. This basin is a vital lifeline for rural Australia. It provides the only source of fresh water for much of the inland regions.

ThargomindahHydro
ThargomindahHydro

The water is stored within a deep layer of sandstone. This sandstone was formed by continental erosion during the Triassic, Jurassic, and early Cretaceous periods. Long ago, much of inland Australia was below sea level. During that time, marine sedimentary rock covered the sandstone. This rock acts as a confining layer, which means it traps the water underneath like a lid. This pressure is what makes the basin "artesian." When a borehole is drilled, the pressure often forces the water to the surface without needing mechanical pumps.

Water enters the system through a process called recharge. Most recharge water enters from relatively high ground near the eastern edge in Queensland and New South Wales. From there, it flows very gradually toward the south and west. A much smaller amount enters along the western margin in arid central Australia. This water moves through the permeable sandstone at a very slow rate. It travels only one to five metres per year. Eventually, the water exits through discharge zones, which include various springs and seeps.

Beels Bore (9014738440)
Beels Bore (9014738440)

The age of this groundwater varies depending on its location. Scientists use carbon-14 and chlorine-36 measurements along with hydraulic modelling to determine its age. In the northern recharge areas, the water is several thousand years old. In the south-western discharge zones, the water is nearly 2 million years old. This shows how incredibly slow the movement of water is through the rock. Before Europeans arrived, this water emerged naturally through mound springs. These springs, such as the Witjira-Dalhousie Springs in South Australia, supported Aboriginal communities and trade routes. They also sustained many endemic invertebrates, including specific types of molluscs.

European discovery of the flowing water began in 1878 near Bourke. Similar discoveries occurred at Back Creek in 1886 and near Cunnamulla in 1887. These findings allowed for the settlement of thousands of square kilometres of country. This land would have been unavailable for pastoral activities without this water. Today, the basin supports cattle stations, irrigation, and domestic use. It even powers a geothermal power station at Birdsville. At Birdsville, the water emerges at 60 degrees Celsius. This provides 25% of the town's electricity needs and serves as their drinking water.

LightningRidgeBaths
LightningRidgeBaths

However, extracting water from the basin is similar to a mining operation. The rate of recharge is much lower than the current extraction rates. In 1915, 1,500 bores provided 130 gigalitres of water per day. Today, the total output has dropped to 40 gigalitres per day. This includes nearly 2,000 freely-flowing bores and over 9,000 that require mechanical power. Many bores are unregulated or abandoned, which leads to significant water wastage. This drop in pressure has caused some mound springs to dry up. This loss of water can lead to the extinction of certain invertebrate species.

Environmental concerns regarding the basin are significant. In 2011, reports revealed concerns about depletion and chemical damage from coal seam gas extraction. In 2009, a process called hydraulic fracturing, or "fracking," at the Myrtle 3 well connected an aquifer to a coal seam. This incident involved the release of potentially toxic chemicals. Scientists have found levels of lead, aluminium, arsenic, barium, boron, nickel, and uranium that exceed recommended limits in some contaminated groundwater. Additionally, there were concerns about injecting carbon dioxide into the basin. Experts warned this could increase water acidity and dissolve rock, releasing heavy metals. Consequently, the Queensland Government banned carbon capture and storage in the basin in May 2024.

LightningRidgeBaths
LightningRidgeBaths

Managing such a massive resource requires cooperation across many different borders. The basin underlies parts of Queensland, New South Wales, South Australia, and the Northern Territory. Each area operates under different laws and management approaches. To help coordinate this, the Great Artesian Basin Coordinating Committee (GABCC) was formed. The GABCC provides advice to government ministers from various levels. It helps coordinate activity between community organisations and government agencies. In 2020, the Australian government published a Strategic Management Plan to help manage these resources sustainably for the future.

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File:LightningRidgeBaths.jpg
LightningRidgeBaths.jpg
File:ThargomindahHydro.jpg
ThargomindahHydro.jpg
File:Beels Bore (9014738440).jpg
Beels Bore (9014738440).jpg
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