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Groundwater

Young seedling of cucumber sprout in ground. Water drops on leaves after watering.

Coastal Aquifers

This is an essential source of fresh water in Australia. The coastal aquifers provide water that is used for various purposes, either domestic, agricultural, or industrial. These aquifers also provide rivers and creeks with baseflow during the dry period, which means they support a diverse ecosystem. Due to drought and population growth, the pressures on freshwater resources in Australia have significantly increased and what used to be scarce is now more scarce. Seawater intrusion can also make this water resource suitable for potable supply and irrigation; this is because excess intrusion will increase the salinity of the water. The rise in sea levels and climate change also have significant effects on the quality and yield of the coastal aquifer system.

Groundwater refers to the water that is found under the soil; it is one of the most important sources of drinking water as well as irrigation of soil. It is found within the spaces and cracks in the sand, soil, and rock and it moves through the geological formation of sand, rocks and soil called aquifers.  Water can move through aquifers because it is permeable due to the large connected spaces within them. Groundwater will move at different speeds, all depending on how wide the space that exists within the aquifers is.

Groundwater is almost everywhere, but the depth of the table differs. While the water table is shallow in some areas, it is deep in others. It could also alternate from deep to shallow due to various factors. For instance, rainfall and snow could cause the water table to rise while heavy pumping of the water may cause it to fall. It is the rain and melting snow that usually replenishes groundwater supplies as they seep into the crevices and cracks beneath the surface. Where the groundwater supply is used at a faster rate than it is replenished, the result would be water shortages, and this is a common phenomenon in some parts of the world.  Without pumping the water, groundwater can come to the surface naturally through springs and can be discharged into streams and lakes. Extraction of this water can be done through a well, and this is where we get to see the depth of the water table. It should be noted that groundwater is not always clean and drinkable, and this happens as a result of the aquifers being permeable and therefore allowing pollutants to get into the water supply.

This provides all the information and advice needed by the Federal, States, and Territory Governments in Australia as well as the community, natural resources authorities, and all other relevant bodies on several issues bordering on groundwater resources.

Groundwater in Australia

As stated above, groundwater is generally found in aquifers. Unlike some countries, the geology of Australia is quite diverse, and the result of this is the diversity in the types of aquifers available as well. Here are the common aquifers;

Alluvial Aquifers

Alluvial deposits are made up of gravel, sand, and clay or silt that accumulates to form sediments on floodplains and river channels.  These deposits are prevalent in Australia and can be found in almost all regions. 20% of all Australia bores are in the alluvial systems and account for 60% of the groundwater extraction in the country. Generally, they are shallower than fractured or sedimentary rock aquifers, and the water level usually fluctuates based on the pumping and recharge rates. Since alluvial deposits are shallow and unconfined, these aquifers are highly susceptible to pollution and contamination.

Fractured Rock

In these aquifers, the groundwater is stored in the joints, fractures, cavities, and bedding planes of the rock. About 40% of Australia groundwater is stored in this manner, and a great percentage of the water can be used for town water supplies, irrigations, domestic use, and stock watering.  An approximate 33% of Australia’s bores are in the fractured rock systems, and they are responsible for 10% of water extraction in the country.

Characterising and determining groundwater flow in fractured rock aquifers is challenging due to the inefficiency of the existing techniques.  The direction of groundwater flow can be because of the orientation of the fractures instead of the hydraulic head distribution. Recharge air replenishment of fractured rock aquifer is intermediate and local.

asphalt texture with cracks on rural road

Sedimentary Basins

These are important groundwater source in Australia. Majority of the basins have a multilayer aquifer system which consists of permeable sediments laid over one another over a long period of time. Good examples of such a basin include the Murray Basin, Officer Basin, and the Great Artesian Basin.  Where the aquifers are intersected, they are recharged by river bed seepage and rivers, and where they outcrop, the recharge is by flood events or infiltration of rainfall.

Paleovalleys

In these aquifers, the groundwater is stored in the joints, fractures, cavities, and bedding planes of the rock. About 40% of Australia groundwater is stored in this manner, and a great percentage of the water can be used for town water supplies, irrigations, domestic use, and stock watering.  An approximate 33% of Australia’s bores are in the fractured rock systems, and they are responsible for 10% of water extraction in the country.

Characterising and determining groundwater flow in fractured rock aquifers is challenging due to the inefficiency of the existing techniques.  The direction of groundwater flow can be because of the orientation of the fractures instead of the hydraulic head distribution. Recharge air replenishment of fractured rock aquifer is intermediate and local.

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