Groundwater

Windmill

Source: Arthur Mostead

Groundwater is water that is found beneath the surface of the earth and makes up 98% of the Earth's available freshwater. To put it another way, groundwater is about 60 times as plentiful as freshwater found in lakes and streams.

Groundwater comes from two main sources. When it rains water seeps down through the soil until it reaches an aquifer. These aquifers may also be in contact with rivers and streams allowing these surface waters to 'drain' into the aquifer. In some places these aquifers can also supply water to rivers and streams.

An aquifer is a body of water-saturated sediment or rock in which water can move readily. Water in the ground travels slowly through pores or fractures depending on the type of sediment or rock material that the aquifer is made of.

There are 2 main types of aquifers, unconfined and confined. An unconfined aquifer is exposed to the surface of the land. A confined aquifer, is an aquifer that has a confining layer that separates it from the land surface.

The depth of the water below the surface is known as the water table.

Groundwater is available throughout large parts of Australia and is the only source of water for many communities in semi-arid and arid zones. A major groundwater resource in Australia is the Great Artesian Basin - the largest groundwater reserve of its type in the world. The Great Artesian Basin is an example of a confined aquifer, covering 22% of the Australian continent and contains water that is up to two million years old.

Although it is less visible than surface water supplies in rivers, lakes and dams, groundwater is a finite resource. It is only replenished when rainfall or surface water seeps into aquifers. If the amount of groundwater removed is more than the amount going in, aquifers are depleted. This undermines efforts to manage stressed surface water resources due to their interconnection and has adverse consequences for communities, agriculture and industry. Due to their nature, aquifers can become contaminated and need to be protected.

More information:

Groundwater and aquifers (National Water Commission)
Groundwater-surface water connectivity (National Water Commission)
Sustainable management of groundwater (National Water Commission)
Groundwater quality (National Water Commission)

Government Programs

Groundwater management is currently the responsibility of state and territory governments. The Australian Government, however, is seeking to provide leadership and coordination for groundwater policy reforms and a focus for resolution of cross-jurisdictional issues.

Australian Government Programs that address groundwater include: