Limestone caves provide measure of Australian groundwater

Nov 26, 2013
Drip loggers measuring water in Cathedral Cave, Wellington (NSW)

Australia's limestone caves hold precious clues to Australia's groundwater – the nation's most important savings bank of fresh water, a leading water scientist says.

As the nation comes to rely increasingly on groundwater to sustain its cities, mining and agriculture, it will be crucial to find out how its aquifers get refilled in order to avoid over-extraction, says Professor Andy Baker of the National Centre for Groundwater Research and Training (NCGRT) and The University of New South Wales (UNSW).

"We're facing a global crisis, and we need to know if we're using our groundwater sustainably, and correctly predict the recharge rates of our aquifers," Prof. Baker says. "Observing water movement in is a cheap and reliable way to do this."

Prof. Baker and his team have been using caves as 'underground rain gauges' to measure the amount of water passing through them. He explains that water flow is extremely uneven – at times of prolonged rainfall, the water can flow very rapidly, but at other times it can be months or years before happens.

The challenge of measuring or predicting its recharge rate is obviously that groundwater is underground, out of sight and therefore not visible to the naked eye, he says. While water managers can drill boreholes into the ground, this is costly and only indicates how much water is available at a particular point in the aquifer, not how or when it got there.

"The great thing about caves is you can just walk into them and observe how the water infiltrates into the ground," Prof. Baker says. "And some caves can be found leading down to an aquifer, and you can directly see the .

Drip water reaching the groundwater, Cathedral Cave, Wellington (NSW)

"It's like standing in a house with a leaky roof. As the water drips and travels through the cave, we can measure where it comes in, how much comes in, and where it goes."

In an ongoing study, the NCGRT researchers have installed the world's largest collection of drip-water measuring devices in Wellington Caves, located in New South Wales. Prof. Baker explains that the drip loggers behave like mini-drums: "Each time the water drips, it triggers a vibration, which is then recorded by a data-logger."

The scientists can then compare the results with recharge estimates created by mathematical models. "It's a cheap, unique and easy way of testing whether the mathematical predictions that we have are correct."

Prof. Baker says the study shows that as water travels through the ground, a lot more of it was lost than expected. "We created an artificial rainfall in one area and only one per cent of the water ended up in the cave.

"We don't know where the rest went – it could have evaporated, flowed somewhere else, or been taken up and transpired by trees and plants.

"This is why observing water movement in caves is useful – it gives you a realistic measurement of what the aquifer might receive, because the groundwater is only 'locked up' when it reaches the water table."

This video is not supported by your browser at this time.

The team also plans to explore stalagmites in the caves, Prof. Baker says. "Stalagmites can only grow if there's groundwater recharge. If we can find out when they grew in the past, we should be able to estimate when recharge has occurred.

"Australia has many limestone caves – they're widespread across eastern Australia, and there are many on the coast stretching from Western Australia through South Australia to New South Wales. So there's big potential for using them as observatories of , and it's an accurate way of predicting when a particular aquifer will be recharged."

Explore further: Turning up the heat on our precious water resources

Provided by National Centre for Groundwater Research and Training

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Australian continent takes a big drink

May 14, 2013

( —Devastating at the time, the major floods of 2011 have since brought a vital benefit by recharging Australia's depleted reserves of underground water.

Million year old groundwater in Maryland water supply

Jun 18, 2012

A portion of the groundwater in the upper Patapsco aquifer underlying Maryland is over a million years old. A new study suggests that this ancient groundwater, a vital source of freshwater supplies for the region east of ...

Recommended for you

Predicting bioavailable cadmium levels in soils

17 hours ago

New Zealand's pastoral landscapes are some of the loveliest in the world, but they also contain a hidden threat. Many of the country's pasture soils have become enriched in cadmium. Grasses take up this toxic heavy metal, ...

Oil drilling possible 'trigger' for deadly Italy quakes

21 hours ago

Italy's Emilia-Romagna region on Tuesday suspended new drilling as it published a report that warned that hydrocarbon exploitation may have acted as a "trigger" in twin earthquakes that killed 26 people in ...

Snow is largely a no-show for Iditarod Trail Sled Dog Race

21 hours ago

On March 1, 65 mushers and their teams of dogs left Anchorage, Alaska, on a quest to win the Iditarod—a race covering 1,000 miles of mountain ranges, frozen rivers, dense forest, tundra and coastline. According ...

UN weather agency warns of 'El Nino' this year

22 hours ago

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

Study shows less snowpack will harm ecosystem

22 hours ago

( —A new study by CAS Professor of Biology Pamela Templer shows that milder winters can have a negative impact both on trees and on the water quality of nearby aquatic ecosystems, far into the warm growing season.

User comments : 0

More news stories

Warm US West, cold East: A 4,000-year pattern

Last winter's curvy jet stream pattern brought mild temperatures to western North America and harsh cold to the East. A University of Utah-led study shows that pattern became more pronounced 4,000 years ago, ...

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

ESO image: A study in scarlet

This new image from ESO's La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that ...

First direct observations of excitons in motion achieved

A quasiparticle called an exciton—responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits—has been understood theoretically for decades. But exciton movement within ...

Patent talk: Google sharpens contact lens vision

( —A report from Patent Bolt brings us one step closer to what Google may have in mind in developing smart contact lenses. According to the discussion Google is interested in the concept of contact ...

Tech giants look to skies to spread Internet

The shortest path to the Internet for some remote corners of the world may be through the skies. That is the message from US tech giants seeking to spread the online gospel to hard-to-reach regions.