Assessing the Status of Groundwater in the Great Artesian Basin

The project ‘Assessing the Status of Groundwater in the Great Artesian Basin’ assessed existing and new geoscientific data and technologies, including satellite data, to improve our understanding of the groundwater system and water balance in the GAB.

An updated classification of GAB aquifers and aquitards was produced, linking the hydrostratigraphic classification used in Queensland (Surat Basin) with that used in South Australia (western Eromanga Basin). This revised hydrogeological framework was produced at the whole-of-GAB scale, through the development and application of an integrated basin analysis workflow, producing an updated whole-of-GAB stratigraphic interpretation that is consistent across jurisdictional boundaries.

Groundwater recharge rates were estimated across eastern GAB recharge area using environmental tracers and an improved method that integrates chloride concentration in bores, rainfall, soil clay content, vegetation type and surficial geology. Significant revisions were made to the geometry and heterogeneity of the groundwater recharge beds, by acquiring, inverting and interpreting regional scale airborne electromagnetic (AEM) geophysical data, identifying potential connectivity between aquifers, possible structural controls on groundwater flow paths and plausible groundwater sources of spring discharge.

A whole-of-GAB water balance was developed to compare inflows and outflows to the main regional aquifer groups. While the whole-of-GAB and sub-basin water balances provide basin-wide perspectives of the groundwater resources, they also highlight the high uncertainties in the estimates of key water balance components that need to be considered for groundwater resource management.

Assessment of satellite monitoring data from Gravity Recovery and Climate Experiment (GRACE) and Interferometric Synthetic Aperture Radar (InSAR) shows promise for remote monitoring of groundwater levels at a whole-of-GAB scale in the future to augment existing monitoring networks.

This presentation was given at the 2022 Australasian Groundwater Conference 21-23 November (https://www.aig.org.au/events/australasian-groundwater-conference-2022/)