Adelaide aquifers face a dry future
Healthy aquifers and groundwater supplies – just as important as Murray River-supplemented reservoirs – are a strategic source of Adelaide’s and South Australia’s long-term sustainability, with water experts warning the Adelaide Hills streams and catchment systems need urgent attention.
In the face of hotter and dryer weather, and following below average rainfall in February, new studies into the water collection in Adelaide and the Mount Lofty Ranges by an international research group has renewed cause for concern.
“We tackled the problem of finding the origin of groundwater under the Adelaide Plains to establish whether the aquifers are recharged through stream infiltration from the mountain front or through subsurface flow from the mountain block,” says Flinders University Strategic Professor of Hydrogeology Okke Batelaan ahead of World Water Day (22 March 2018).
Research published in Hydrology and Earth System Sciences found that the sustainability of groundwater extraction is more limited than previously thought.
Research published in Hydrology and Earth System Sciences found that the sustainability of groundwater extraction is more limited than previously thought.
Conceptual diagram of the Adelaide Plains aquifers recharge mechanisms. Courtesy Etienne Bresciani, National Centre for Groundwater Rresearch and Training at Flinders.
“Our data consistently suggest that streams are gaining from groundwater in the Mount Lofty Ranges and losing water when entering the basin, thereby recharging the aquifers under the Adelaide Plains,” says Dr Etienne Bresciani, the lead author on the paper.
“Even the relatively deep Tertiary aquifers appear to be recharged through this mechanism and not through subsurface flow from the mountain block,” says Flinders University adjunct Dr Bresciani now based at the Korea Institute of Science and Technology.
“This means the ability of our groundwater to supply water is more limited than previously thought,” says Professor Batelaan, also a chief investigator at the National Centre for Groundwater Research and Training (NCGRT) at Flinders University.
Since the 1950s groundwater levels have significantly decreased due to increasing extraction of groundwater from the Adelaide region.
The new research also highlights the need to protect and more rigorously manage streams and rivers in both the Adelaide Plains and Mount Lofty Ranges to ensure the quality and quantity of precious groundwater on the Adelaide Plains.
“Groundwater management, investigations and modelling should focus more on protecting, understanding and estimating recharge from streams and creeks,” Dr Bresciani says.
Other NCGRT experts in the study include Dr Peter Cook and Dr Eddie Banks, along with Dr Roger Cranswick from the Department of Environment, Water and Natural Resources (DEWNR) in SA and Dr Jordi Batlle-Aguilar from the Kansas Geological Survey at the University of Kansas.
The investigation into Adelaide’s mountain-front and mountain-block recharge involved full use of the State Government databased including thousands of electrical conductivity and groundwater level measurements.