Groundwater recharge at the eastern intake beds of the Great Artesian Basin using multi-isotope studies

Objectives: Large sedimentary basins with multiple aquifer systems, such as the Great Artesian Basin (GAB) in Australia, are difficult to study because of the very large time scales associated with groundwater flow. The GAB is the world’s largest and deepest artesian groundwater basin and has become increasingly stressed due to demand from multiple competing industries (agriculture, oil, coal and gas). Quantifying groundwater recharge is crucial for understanding the water balance for this economically and culturally important multi-aquifer system. The complexity of the GAB can only be dealt with by applying multiple lines of evidence including environmental isotopes, supported by hydrochemical, sedimentological, and geophysical observations. Design and Methodology: Three studies on the recharge areas of the GAB investigated recharge to the Hutton Sandstone and the Precipice Sandstone (QLD) and the Pilliga Sandstone (NSW). Multiple environmental tracers (major ion chemistry, 18O, 2H, 3H, 13C, 14C, 36Cl, 87Sr/86Sr, 85Kr, 81Kr, noble gases) were measured. Recharge rates were derived from tracer concentration profiles and aquifer cross-sections with porosity derived from previous studies. Conclusions: Tracer results in the Precipice Sandstone are consistent with pumping test data and re-injection of coal seam gas produced water, suggesting high hydraulic conductivities. They provided the first estimate of average long-term annual recharge to this deep confined aquifer, which is of a similar order of magnitude as today’s industrial re-injection of CSG water. © The Authors

Keywords

Sedimentary basins, Aquifers, Australia, Ground water, Artesian basins, Industry, Agriculture, Queensland, New South Wales, Tracer techniques, Sandstones

Citation

Sucknow, A., Deslandes, A., Gerber, C., Taylor, A., Raiber, M, Barrett, D., & Meredith, K. (2019). Groundwater recharge at the eastern intake beds of the Great Artesian Basin using multi-isotope studies. Paper presented to the Australasian Groundwater Conference, "Groundwater in a Changing World", 24 - 27 November 2019, Brisbane Convention and Exhibition Centre, Queensland. Retrieved from: http://www.groundwater.com.au/documents/agc2019-book-of-abstracts-updated.pdf

URI

http://www.groundwater.com.au/documents/agc2019-book-of-abstracts-updated.pdf
https://apo.ansto.gov.au/dspace/handle/10238/11552

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