Freshwater reserves under the sea
Research at Flinders University is investigating and locating vital freshwater hidden beneath the sea.
Flinders University Professor of Hydrogeology Adrian Werner is making important advances in assessing freshwater reservoirs that exist beneath the ocean, potentially providing innovative answers to escalating global water supply issues.
He is among several speakers at the Australasian Groundwater Conference being held at the Brisbane Convention & Exhibition Centre from 24-27 November.
"Since the late 1960s, groundwater scientists have been intrigued by evidence of freshwater beneath the sea, and in the following decades, understanding subsea fresh groundwater has advanced and is now understood to be a global phenomenon," he says.
"I've been studying the extent of freshwater under the sea, through my Australian Research Council Future Fellowship, and have made significant inroads into our current knowledge of offshore freshwater."
The work involving offshore aquifers has led to the publication of seven significant papers that cover a range of issues—from improving methods of obtaining offshore freshwater estimates, to better understanding how onshore events influence and affect subsea freshwater aquifers.
Several severe recent water shortages in coastal cities around the globe—including Cape Town during 2018—have raised the possibility of accessing offshore freshwater, even if only as an emergency measure.
However, Professor Werner warns that current knowledge of the extent of offshore freshwater is limited, and questions already exist whether humans are drawing on offshore freshwater reserves while pumping fresh groundwater from coastal aquifers.
"Our research is addressing whether we are already accessing offshore freshwater or whether this is a largely untapped resource that is yet to be exploited," he says.
Two papers have focused on offshore freshwater in key Australian coastal aquifer systems—in Perth and the lower southeast of South Australia.
"These are the first two attempts to study Australian offshore aquifers, and we found considerable offshore freshwater resources in both cases.
"These are ancient bodies of freshwater that are either in balance with onshore aquifer conditions or are in the process of depleting," explains Professor Werner.
He says another exciting area of research has been studying delicate freshwater resources on small islands, including Pacific nations where sea-level rise threatens their water supplies.
"We uncovered major revelations about Kiribati's freshwater resources that have implications for groundwater management more generally."
As well, Professor Warner recently completed an ARC Linkage project with the SA Government looking at the groundwater in floodplains adjacent to the River Murray.
"We made some remarkable discoveries about freshwater next to the river in otherwise saline aquifers that defies accepted knowledge on aquifer-river interactions," says Professor Werner, who was recently identified by The Australian newspaper as Australia's research field leader in Hydrology and Water Resources.
Silvia C. Solórzano-Rivas et al. Dispersion effects on the freshwater–seawater interface in subsea aquifers, Advances in Water Resources (2019). DOI: 10.1016/j.advwatres.2019.05.022
Leanne K. Morgan et al. A conceptual study of offshore fresh groundwater behaviour in the Perth Basin (Australia): Modern salinity trends in a prehistoric context, Journal of Hydrology: Regional Studies (2018). DOI: 10.1016/j.ejrh.2018.10.002
Andrew C. Knight et al. The onshore influence of offshore fresh groundwater, Journal of Hydrology (2018). DOI: 10.1016/j.jhydrol.2018.03.028
Adrian D. Werner et al. Revisiting analytical solutions for steady interface flow in subsea aquifers: Aquitard salinity effects, Advances in Water Resources (2018). DOI: 10.1016/j.advwatres.2018.01.002
S.C. Solórzano-Rivas et al. On the representation of subsea aquitards in models of offshore fresh groundwater, Advances in Water Resources (2017). DOI: 10.1016/j.advwatres.2017.11.025
Mark Bakker et al. Evaluation of analytic solutions for steady interface flow where the aquifer extends below the sea, Journal of Hydrology (2017). DOI: 10.1016/j.jhydrol.2017.04.009