What is Groundwater?

Why is groundwater important?

Groundwater allows people to live in places where surface water is scarce. In much of rural South Australia it the sole water supply for stock and domestic purposes. It provides water for irrigation and industry. Most of our premium wine districts rely on groundwater.

An old steam engine, once used to pump water, now stands neglected near a more modern artesian bore on the edge of the Simpson Desert north of Birdsville, Queensland

Keeping our lakes full

Groundwater is also an important ecological resource. It helps keep our rivers and lakes full, and sustains a wealth of plants of animals. Some of our ecosystems are dependent on groundwater for their survival.

Because groundwater is a hidden resource, both its purity and availability are usually taken for granted.

Did you know? - The bottled water so many of us drink is actually groundwater.

Do we have enough groundwater?

We can run out of groundwater if more water is withdrawn by pumping (discharge) than is fed by recharge from the surface. This is a problem considering that in many areas groundwater is being withdrawn in increasing quantities to meet growing demands and development pressures. These human demands compete with natural uses.

Unsustainable groundwater extraction won't only mean less water for human use; it will also have an impact on the environment. For example, plants in the riparian zone that grew because of the close proximity of the water table to the land surface may not survive as the depth to water increases. The environment for fish and other aquatic species also may be altered as the stream level drops or dries up altogether.

To manage groundwater resources effectively, we need to understand how these systems operate, monitor allocation and extraction, and establish a sustainable groundwater yield for each system.

Are there other threats to groundwater?

Pollutants can contaminate groundwater, posing a risk to human health. Potential sources of pollution include seepage from septic tanks and landfill, leakages from underground fuel tanks, soluble chemicals from industrial activities, detergents, and pesticides and fertilisers used in agriculture.

Salt pollution

Groundwater can also become polluted with salt! The most common cause of salinity is the replacement of perennial, deep-rooted native vegetation with crops and pastures used in agriculture. Because crops and pastures use less of the incoming rainfall this unused water either runs off into streams, rivers and lakes, or infiltrates beyond the root zone where it accumulates as groundwater. As the groundwater level rises, salts that have accumulated over thousands of years in the subsoil rise with it, degrading wetland habitats and water resources.

Yet another threat occurs in coastal regions, where freshwater aquifers can become 'polluted' with salt water. This happens when seawater seeps into the groundwater, often because there has been an excessive pumping of groundwater from a well that has been developed at the boundary of freshwater and saltwater.

Adequate controls are therefore important to safeguard the quality of groundwater resources.

Read a case study: South Australia's Groundwater

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