Groundwater in Australia

Groundwater is found in aquifers which are geological formations able to store and transmit water. The geology of Australia is diverse, therefore the types of aquifers vary, examples include:

Alluvial Aquifers
Formed of sediments such as gravel, sand and silt deposited by rivers or other running water.
Coastal Aquifers
Deposits of sand formed along the coast by wind and water.
Fractured Rocks
Fractures and fissures within hard and impermeable rock (such as granite) that are able to store and transmit water.
Sedimentary Basins
Relatively large areas where thick layers of sedimentary rock (such as sandstone, siltstone and conglomerate) have been deposited over many years.
Palaeovalleys
Alluvial deposits formed by ancient rivers that are no longer active. These deposits can be buried by other sediments.
Karst
Limestone or dolomite rock formations partly dissolved by water to form fissures, sinkholes and caves.

The six categories are broadly representative of the key geological and topographic provinces across the continent, and are mappable at a national scale using consistent datasets. Climate controls the mode and seasonality of water movement; for example, the hydrology of a stream in a narrow alluvial valley will be different in wet temperate Tasmania (where hydrological processes are dominated by regular, winter-dominated rainfall) than in the arid interior (where hydrological processes are controlled by high evaporation and infrequent, variable rainfall).