Australia: The Land Where Time Began

A biography of the Australian continent 


Being the driest vegetated continent in the world, Australia lacks the large, permanently flowing rivers and deep permanent lakes found elsewhere. There are, however, a variety of groundwater systems. Particularly in the arid central regions of the continent, the rivers rely in varying degrees on groundwater for their flows. Rivers can have an addition of baseflow from the hyporheic zone in regions where they usually get reasonable rainfall. The porosity of the sediment determines the volume of water exchanged between the river and subsurface water.

Arid zone rivers often have subsurface flows, some being a series of pools for years at a time, or their beds can be completely dry for long stretches of their course between floods. River red gums can be found lining river courses in arid country, even for some distance into desert country, because, as in many native plants, they have deep root systems that can grow down to the water table. In this way they survive in good health for years of drought at a time.

Groundwater ecosystems

There are 4 categories of ecosystem that are dependent on groundwater, river baseflow systems, aquifer and cave ecosystems, terrestrial vegetation and wetlands. The effect on these ecosystems of over extraction or addition of pollutants can be severe, and even catastrophic. Disruption of the exchange can have severe consequences on these ecosystems. Perth, Western Australia, gets about 60 % of its water supply from unconfined aquifers of the Swan Coastal Plain. Because of this, it can be seen as an ecosystem threatened by the same problems as natural ecosystems, overuse and pollution.

There is a wide range of subsurface water systems in Australia, the Great Artesian Basin (GAB) being the largest, at about 1.7 km2 it also the largest known in the world.

Sources & Further reading

Mary E. White, Earth Alive, From Microbes to a Living Planet, Rosenberg Publishing Pty. Ltd., 2003




Author: M. H. Monroe
Last updated 25/02/2010 





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