Groundwater is often contaminated from mining operations and infiltration and is frequently overdrawn for use in combatting drought. Now, such impacts can be measured more precisely using water-tracing technology developed by researchers from the University of New South Wales (UNSW). This area was of particular interest because six underground coal mines operate within the Sydney water supply catchment, and underneath wetlands and sensitive ecosystems, the release noted. 

"All underground engineering projects have the potential to have an impact on groundwater," Katarina David, a Ph.D. candidate from the UNSW Connected Waters Initiative (CWI), said in a news release. "So it is essential we understand how the water falling on the surface finds its way to the aquifers deep underground."

For their study, UNSW researchers took several 300-meter-deep core samples from the Illawarra plateau of New South Wales and analyzed small moist core sections in a laboratory setting.

"We identified the different isotopes of hydrogen and oxygen in the water, which allowed us to work out where the water came from. We identified four distinctive layers of rock, or hydrogeological zones, which control groundwater movement in the Sydney Basin," Professor Andy Baker, the UNSW Centre Director, said in the release.

Water moves very slowly underground and takes a long time to reach 300 meters, the researchers noted. The isotopes were fairly similar among the deep core samples and compared to modern rainfall. This signifies that the groundwater system in the Sydney Basin has been relatively stable for thousands of years. Researchers can use this finding as a baseline for detecting future changes in groundwater flow and quality.  

"Our research has global relevance as well because this new technology provides a quick and cheap alternative to having to install numerous boreholes for groundwater monitoring." Dr. Wendy Timms, one of the study's authors from CWI, explained in the release.

The study recently published in the journal Science of the Total Environment

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