Great Artesian Basin

The Great Artesian Basin ( engl. Great Artesian Basin ( GAB) ) in Australia is one of the largest underground aquifers worldwide and extends over 1.711 million square kilometers. This represents about 23 percent of the area of the Australian continent.

Area and use

The basin is one of the main elements of the geology of Australia and covers large parts of the state of Queensland, the south-east corner of the Northern Territory, the northeastern part of South Australia and northern New South Wales. The water reservoir extends from the Great Dividing Range to Lake Eyre. Its longest dimension is 2400 km from Cape York in the north to Dubbo in the south and 1,800 kilometers from the Darling Downs in the east to the west of Coober Pedy.

The fresh water is estimated at 64,900 cubic kilometers. This corresponds to the amount of water of a lake with the size of the pelvis and an average water depth of 38 meters, respectively, the 130,000 times the volume of Sydney Harbour. It was discovered in 1878 by European settlers and extends below approximately a quarter of the Australian continent from. This discovery has a huge economic boom was triggered because the water can be used widely for livestock in terms of animal husbandry. The underground water is pumped by means of wind turbines, diesel and electric pumps. In many places the water has a very high salt content.

The rock deposits, where the water reservoir is included, arose before 100 to 250 million years ago. The reservoir rock, a thick sequence of sandstones of the Triassic, the Jurassic and the Cretaceous forms in several far-flung, merging the bowl-shaped structures to the underground of the Great Artesian Basin. The up to 3000 m thick sandstone formation is sealed by a series of layers of fine-grained marine sediments upward, downward form the older rocks (older than Jurassic) the seal.

Origin

Especially in the eastern area of the Great Dividing Range is found over a wide area of the earth's surface a pending porous rock layer. There rainwater can penetrate the soil and penetrate as groundwater slowly to the west and south. To the west and northwest of the precipitation due to the desert climate is low, so that there hardly groundwater is newly formed. In the central region it can be like emerging from an artesian source. The extracted groundwater would not reach the lying to the south of the basin sources in the area of Dalhousie Springs, Lake Eyre, Lake Frome, Bourke and Bogan River to about two million years ago. Another theory is based on a fossil groundwater basins, similar to the Libyan desert.

Risks

The extraction of groundwater has some problems. With overuse, the lowering of the groundwater level leads here in addition to the penetration of ( salty ) sea water, whereby the groundwater for decades for human consumption unfit for human consumption and for irrigation in agriculture is useless. Another problem of the aquifer is the increasing pollution caused by leaks in manure pits, landfills and by emissions from industrial plants.

The Great Artesian Basin Coordinating Committee ( GABCC ) not only coordinates the water demand by the federal government and the local governments, but they also monitored.

Cultural Significance

Long before the European settlement of Australia Aboriginal people used the natural spring outlets of the Great Artesian Basin. They were regarded as reliable sources of water in times of drought when other sources dried up. The water exits were and are of great significance for the traditional Aboriginal culture: Many stories of the Dreamtime and drawings relate the sources of the Great Artesian Basin and their placement along paths of travel with one. Some of the sources are found in the myths of Aborigines and thus support the spiritual and cultural beliefs of the indigenous communities relevant.

The sources are also still valuable for wildlife here.