SYDNEY — Oct. 2, 2015 — Researchers in Australia have developed a new approach to determine how groundwater moves in the different layers of rock below the surface, according to a press release.
According to the University of New South Wales (UNSW), the study could help protect groundwater by providing a baseline against which any future impacts on water quality from mining operations, groundwater abstraction or climate change can be assessed.
Working in the Sydney Basin, the team obtained a 300-meter deep core drilled through layers of sandstone and claystone. Small sections of the moist rock from the core were carefully preserved and analyzed in the lab.
“The best tracer of water is water itself. So we directly analyzed the groundwater in the pores of the rock from different depths and rock types, using the latest laser technology,” explained UNSW Centre Director Professor Andy Baker in the release.
“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.
“The water moves very slowly underground, and has taken a long time to reach a depth of 300 meters. But we found the isotopic composition of the deep water was similar to that of modern rainfall, which means the system in the Sydney Basin has been relatively stable for thousands of years.
“Using this as a baseline we can detect any future changes in water flow or water quality.”
Study author Dr. Wendy Timms, from the UNSW Connected Waters Initiative (CWI), said that the research has global relevance because this technique provides a fast and inexpensive alternative to installing numerous boreholes for groundwater monitoring.
The team’s findings have been published in the journal Science of the Total Environment.