<div>Airborne electromagnetics (AEM) is a geophysical technique used for estimating the bulk conductivity profile of the upper 300 m (approximately) of the subsurface. The AEM data acquired as part of the Exploring for the Future program AusAEM Eastern Corridor survey (Ley-Cooper 2021) covers much of the central Kati Thanda - Lake Eyre Basin (KT–LEB). Data for these regional surveys were acquired using the TEMPEST AEM system at a nominal 20 km line spacing.</div><div>&nbsp;</div><div>The prevalence and relative consistency of large sand-rich sediment zones across the Cooper Creek Palaeovalley (Evans et al. 2024) means that AEM data are potentially useful for inferring the distribution of groundwater salinity beneath the floodplain and surrounds. To visualise salinity from AEM data in a map, the thickness weighted average bulk conductivity was calculated for the 15 m depth interval beneath the watertable along the AEM survey lines. Symington et al. (2024) details the rationale and methods to produce the AEM bulk conductivity points. Symington et al. (2024) also included the code embedded in a jupyter notebook written to calculate bulk conductance points from AEM line data and undertake an uncertainty analysis to assess the likelihood of the conductance response to be related to groundwater (note that the link to the code is contained in the Symington et al. 2024 reference).</div><div>&nbsp;</div><div>In conjunction with sparse groundwater salinity and water level data from existing bores, Symington&nbsp;et al. (2024) used the conductance data to provide insights to address the following questions:</div><div>1. What is the regional scale distribution of groundwater salinity within the shallow alluvial aquifer?</div><div>2. Where does the shallow aquifer host fresh water?</div><div>3. What areas are most likely to receive recharge from the flanks of the floodplain?</div><div>4. Is there evidence for the groundwater discharging into the river?</div><div>&nbsp;</div><div>Data from Symington et al. (2024) were used to infer salinity across the Cooper Creek floodplain and Strzelecki Desert, as well as to determine the location of potential fresh groundwater lenses beneath Cooper Creek floodplain in SA and Queensland. The groundwater bore and uncertainty analysis suggests good correlation exists between groundwater bore data and AEM conductance points, where groundwater occurs at shallow depths in areas including the Cooper Creek floodplain, Strzelecki Desert, and Coongie Lakes. Data analysis, interpretation and results are in Symington et al. (2024) and further discussed in Evans et al. (2024), Symington et al. (2023) and Symington et al. (2022).</div><div>&nbsp;</div><div>References</div><div>Evans TJ, Bishop C, Symington NJ, Halas L, Hansen JWH, Norton CJ, Hannaford C and Lewis SJ (2024) Cenozoic geology, hydrogeology, and groundwater systems: Kati Thanda – Lake Eyre Basin, Record 2024/05, Geoscience Australia, Canberra, http://dx.doi.org/10.26186/147422.</div><div>&nbsp;</div><div>Ley-Cooper AY (2021) Exploring for the Future AusAEM Eastern Resources Corridor 2021 Airborne Electromagnetic Survey TEMPEST® airborne electromagnetic data and GALEI inversion conductivity estimates [data set], Geoscience Australia, https://ecat.ga.gov.au/geonetwork/srv/api/records/145744, accessed 14 December 2023.</div><div>&nbsp;</div><div>Symington N, Evans T, McPherson A, Buckerfield S, Rollet N, Ray A and Halas L (2024) Characterising surface water groundwater interaction using airborne electromagnetics: a case study from the Cooper Creek floodplain, Queensland, Australia, workflow release, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/149176.</div><div>&nbsp;</div><div>Symington N, Evans T, Rollet N, Halas L, Vizy J, Buckerfield S, Ray A, LeyCooper Y and Brodie R (2023) Using regional airborne electromagnetic conductivity data to characterise surface water groundwater interaction in the Cooper Creek floodplain in arid central eastern Australia, Geoscience Australia, Canberra, https://pid.geoscience.gov.au/dataset/ga/147716.</div><div>&nbsp;</div><div>Symington N, Halas L, Evans T and Rollet N (2022) Mapping freshwater lenses in the Cooper Creek floodplain using airborne electromagnetics, Geoscience Australia, Canberra, https://pid.geoscience.gov.au/dataset/ga/147039.</div>

<div>This report brings together data and information relevant to understanding the regional geology, hydrogeology, and groundwater systems of the South Nicholson – Georgina (SNG) region in the Northern Territory and Queensland. This integrated, basin-scale hydrogeological assessment is part of Geoscience Australia’s National Groundwater Systems project in the Exploring for the Future program. While the northern Georgina Basin has been at the centre of recent investigations as part of studies into the underlying Beetaloo Sub-basin, no regional groundwater assessments have focused on central and southern parts of the Georgina Basin since the 1970s. Similarly, there has been no regional-scale hydrogeological investigation of the deeper South Nicholson Basin, although the paucity of groundwater data limited detailed assessment of the hydrogeology of this basin. This comprehensive desktop study has integrated numerous geoscience and hydrogeological datasets to develop a new whole-of-basin conceptualisation of groundwater flow systems and recharge and discharge processes within the regional unconfined aquifers of the Georgina Basin.</div><div><br></div><div>Key outputs arising from this study include: (1) the development of a hydrostratigraphic framework for the region, incorporating improved aquifer attribution for over 5,000 bores; and (2) publicly available basin-scale groundwater GIS data layers and maps, including a regional watertable map for the whole Georgina Basin. This regional assessment provides new insights into the hydrogeological characteristics and groundwater flow dynamics within the Georgina Basin, which can aid in the sustainable management of groundwater for current and future users reliant on this critical water resource.</div><div><br></div><div><br></div>

<div>The Kati Thanda – Lake Eyre Basin (KT–LEB) covers about 1.2 million square kilometres of outback Australia. Although the basin is sparsely populated and relatively undeveloped it hosts nationally significant environmental and cultural heritage, including unique desert rivers, sweeping arid landscapes, and clusters of major artesian springs. The basin experiences climatic extremes that intermittently cycle between prolonged droughts and massive inland floods, with groundwater resources playing a critical role in supporting the many communities, industries, ecological systems, and thriving First Nations culture of the KT–LEB.</div><div><br></div><div>As part of Geoscience Australia’s National Groundwater Systems Project (in the Exploring for the Future Program) this report brings together contemporary data and information relevant to understanding the regional geology, hydrogeology and groundwater systems of Cenozoic rocks and sediments of the KT–LEB. This work represents the first whole-of-basin assessment into these vitally important shallow groundwater resources, which have previously received far less scientific attention than the deeper groundwater systems of the underlying Eromanga Basin (part of the Great Artesian Basin). The new knowledge and insights about the geology and hydrogeology of the basin generated by this study will benefit the many users of groundwater within the region and will help to improve sustainable management and use of groundwater resources across the KT–LEB.</div><div><br></div>