Groundwater isotopic record in southwest Australia: links to recharge variations and climatic conditions

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Date
2018-12-10
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Publisher
Australiasian Quaternary Association Inc.
Abstract
Groundwater resources are a reliable and important source of water. Considering most large groundwater basins can contain ‘old’ groundwater where extraction exceeds groundwater recharge, knowledge of the past conditions and timing under which groundwater was recharged is needed to sustainably manage groundwater resources. Applying isotopic tools to groundwater contained in regional aquifer systems can provide low-resolution information on recharge intensity, recharge source and past climatic conditions for the region. Furthermore, an understanding of how groundwater recharge and climate have been connected in the past can be used to inform climate adaptation strategies for sustaining groundwater resources during climate change. Large regional groundwater systems, contained within the Perth Basin in southwest Australia were investigated in this study to provide information on groundwater recharge and climate over the past 35,000 years. Regional scale databases containing groundwater age and isotopic records are not commonly developed in Australia and are generally more site specific. Therefore, this Perth Basin database provides a unique opportunity to study and interpret a low-resolution palaeo-archive of groundwater recharge for southwest Australia. Groundwater ages (14CDIC) and stable O isotopes of water (δ18O) from two regional groundwater systems within the Perth Basin have been collated and groundwater ages calculated. The trends δ18O over time in the regional groundwater data are consistent with the groundwater flow line data supporting our hypothesis that groundwater δ18O is a proxy for palaeo-recharge. The Southern Perth Basin groundwater isotope record is interpreted to be a low resolution archive of recharge driven by changes in the relative intensity of past rainfall and recharge thresholds. This long-term stable isotopic recharge record provides a greater understanding of groundwater palaeo-recharge, as well as how recharge and climate have been connected in the past. © Author(s)
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Keywords
Ground water, Climates, Water, Water reservoirs, Isotopes, Australia, Western Australia, Groundwater recharge
Citation
Priestley, S. (2018). Groundwater isotopic record in southwest Australia: links to recharge variations and climatic conditions. Paper presented at AQUA Biennial Conference, Canberra, 10-14 December 2018. (pp. 53). https://aqua.org.au/wp-content/uploads/2019/10/AQUA-2018-Program.pdf