Australian environmental scientists used cave stalagmites as a record of groundwater replenishment over time in a first-of-its-kind study that demonstrated that the level of rainfall currently recharging groundwater in southwest Washington is at its lowest level for at least 800 years.
According to the evidence, decreased rainfall has resulted in a decline in rainfall recharge to groundwater in southwest Australia over the past two decades.
Using stalagmites and ceiling dripwater from caves between the surface of the earth and the groundwater table, this scientific development was made. Communications Earth & Environment has published the study.
Cave stalagmites can form when water passes through the cave from the surface to the groundwater. Utilizing the oxygen isotopic composition (18O), these stalagmites can be used to obtain records of previous groundwater replenishment, also known as recharge. According to the stalagmites gathered for this study, the reduction in rainfall has decreased groundwater recharge.
“We are now attempting to extend the record back to 10,000 years in order to determine when groundwater was recharged and under what past climate scenarios this occurred. This means we can better understand the boundaries and long-term viability of this crucial resource for people that rely significantly on groundwater,”
Dr. Stacey Priestley,
The most compelling aspect of the study, according to co-author Prof. Andy Baker of UNSW’s School of Biological Earth and Environmental Sciences, was watching this groundwater record change over the past few years as more stalagmite data was collected.
“The results of our research demonstrated that records from the most recent decades were novel. Utilizing stalagmites to provide historical records of groundwater recharge opens up a new “toolbox” with this approach. The ability will permit us to more readily comprehend how to reasonably deal with our groundwater asset later on.”
Dr. Pauline Treble, a senior research scientist at ANSTO, and Dr. Stacey Priestley, formerly of ANSTO and the University of Adelaide, led the research.
“By examining 18O in stalagmites, we can survey how precipitation re-energize rates have changed throughout significantly longer time spans,” said Dr. Priestley.
According to Dr. Pauline Treble’s explanation, the Southwest Australia region gets approximately 75% of its water needs from groundwater. Dr. Treble stated, “The research highlights the resource’s vulnerability.”
Work will continue to extend the current record further back in time because it only goes back 800 years.
“We are currently attempting to extend the record back 10,000 years in order to learn when groundwater was recharged and under what climate scenarios it occurred in the past. Dr. Priestley stated, “This means we can better comprehend the limits and sustainability of this valuable resource for communities that heavily rely on groundwater.”
For the CRY-S1 chronology, the researchers mapped the strontium using the XFM beamline at the Australian Synchrotron of the ANSTO.
The Wadandi Noongar people are acknowledged by the authors as the spiritual and traditional stewards of the study area.
More information: Stacey C. Priestley et al, Caves demonstrate decrease in rainfall recharge of southwest Australian groundwater is unprecedented for the last 800 years, Communications Earth & Environment (2023). DOI: 10.1038/s43247-023-00858-7
