Groundwater provides almost one-third of the nation’s water and is worth more than $34 billion to the economy, but results from a recent major review have prompted scientists to call for urgent and better appraisal of groundwater and how we manage it.
What is groundwater?
When rain falls to the land surface, water flows away to streams, rivers, lakes and eventually to the ocean, but some water seeps into the ground to accumulate within cracks or pores in the rocks, called aquifers.
Aquifers are found in a variety of geologies including fractured rocks; sediments such as gravel, sand and silt; sand deposits along the coast; and in thick layers of sedimentary rocks like sandstone or siltstone.
Some of the collected water will flow back to rivers and streams, while some will be recovered to the surface via wells or pumping.
In fact, groundwater makes up about 17% of the accessible water in Australia and provides for almost one-third of our total water use.
Australia’s most well-known aquifer is a very large hydrogeological system called the Great Artesian Basin (GAB), which covers more than 1.7 million square kilometres under three States – Qld, NSW, SA – and parts of the NT.
Other groundwater systems are not as big.
But it’s knowing the quality of the groundwater and how much water can be drawn from an aquifer that helps hydrogeologists decide whether a groundwater source is best suited for human use, or for stock water supplies, irrigation, or mining.
Problems with groundwater management are varied, but are particularly acute in regional areas where they are likely to have serious long-term impacts for food production.
Reviewing groundwater in Australia
Dr Peter Cook, Professor of Hydrogeology at Flinders University, led the team of researchers who identified 18 threats to the sustainable management of Australian groundwater and then surveyed groundwater professionals to rank the issues.
Participants were asked to “score challenges (to groundwater management) on a scale of 1–5, 1 being “not an impediment” and 5 being a ‘major impediment’”.
The survey, distributed by the National Centre for Groundwater Research and Training, received 95 responses.
The study found the highest-ranked challenge was determining the limit on how much water can be drawn from a region’s underground water storages.
Also in Cosmos: Groundwater extraction a “ticking time bomb”
Unregulated pumping joined over-extraction as the most pressing problems contributing to water table declines, which could lead to impacts for water users and groundwater-dependent ecosystems.
Other topics examined included: characterising groundwater and the amount and quality of data available to do so; understanding when groundwater extraction may lead to deterioration in water quality; groundwater-dependent ecosystems; the interaction between groundwater and surface water; modelling groundwater behaviour when many variables affecting it are uncertain; and the governance of groundwater and its fragmented nature in Australia, especially across state borders.
The research is published in the Journal of Hydrology: Regional Studies.
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