Sebastian Pfautsch

Sebastian Pfautsch

Mining below groundwater tables is increasing globally, but little is known about what happens to nearby trees and ecosystems when groundwater is diverted around mines to prevent the flooding of pits. That's where Dr Sebastian Pfautsch, from the University's Hawkesbury Institute for the Environment, comes in.

Sebastian's research, along with the rest of his colleagues at HIE, is leading the world. In the recent Excellence in Research for Australia (ERA) report, the HIE received five ERA 5 ratings in the disciplines to which it contributes research. An ERA 5 ranking means "well above world standard" and is the highest ranking possible.

To examine the effect of mining on ecosystems around Australia, Sebastian, in partnership with Rio Tinto Iron Ore, the department of Water of Western Australia, and the University of Western Australia, studied eucalypts near open-cut mines in the Pilbara region in north-western Australia.

"We know Australian trees, such as eucalypts, can extend roots 30 meters or deeper into the ground to find water," says Sebastian.

"What we examined in this study is how these trees respond when nearby mine operations start changing their underground water supplies."

To fully understand the impact of mining, Sebastian assessed the health of trees by measuring their water use at sites where groundwater levels had artificially been lowered or raised.

He says the water use of trees some several kilometres away from mine sites was sensitive to changes in groundwater levels.

"The tight connection between water use and the growth of trees implies that a reduction in water use will lead to a reduction in growth. In extreme cases trees will die of thirst," Sebastian says.

The good news is negative effects on tree health as a consequence of declining groundwater could be detected relatively early by monitoring their water use and other indicative parameters related to their growth.

 "Doing this can provide options to adjust water management strategies, similar to what we see in the Pilbara," Sebastian says.