This report presents key results of groundwater level interpretations from the Upper Burdekin Groundwater Project in North Queensland, conducted as part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. The Upper Burdekin Groundwater Project is a collaborative study between Geoscience Australia and the Queensland Government. It focuses on basalt groundwater resources in two geographically separate areas: the Nulla Basalt Province (NBP) in the south and the McBride Basalt Province (MBP) in the north. This report interprets groundwater levels measured in both provinces by Geoscience Australia and the Queensland Government to provide recommendations for resource management. The NBP and MBP basalt aquifers are heterogeneous, fractured, vesicular systems. Several lava flows are mapped at surface in both provinces, and the degree of hydraulic connectivity between these flows is unclear. Although there was some uncertainty due to monitoring well construction issues, barometric efficiency analyses from supporting project documents suggest that the basalts of the NBP and MBP were unconfined where monitored during the EFTF project. That finding generally matches observations presented here. Longer term groundwater hydrographs suggest that groundwater levels have been declining in the NBP and MBP following major flooding in 2010-2011 related to one of the strongest La Niña events on record. Groundwater levels are yet to decline to pre-flood elevations in places. Importantly, these longer term hydrographs set the project in context: the EFTF monitoring period is only a small fraction of a much longer-functioning, dynamic groundwater system. Nulla Basalt Province The NBP is elongated east-west, and is situated entirely within the Burdekin River catchment. Volcanic vents in the west identify that area as the main extrusive centre. Regionally, groundwater migrates through the basalts of the NBP from the western high ground towards the Burdekin River in the east. Although lava flows of the NBP reach the Burdekin River, direct groundwater discharge in this area has not yet been proven. However, groundwater does discharge to various springs and surface watercourses in the NBP that are known tributaries of the Burdekin River. Despite the presence of many registered extraction bores, no clear signs of pumping were observed in groundwater hydrographs from the NBP during the EFTF monitoring period. Water levels in many bores responded to major rainfall events, ranging from a simple change in declining hydrograph slope to a water level increase of ~6.8 m in the central west. While some responses could have been induced by loading, electrical conductivity loggers and the extent of water level rise showed that many were clearly caused by recharge. At nested monitoring locations, groundwater levels remained commensurate with downward flow potentials throughout the EFTF monitoring period. McBride Basalt Province The MBP is approximately circular in plan, with volcanic vents present in a north-northeast trending band through the province centre. Lava flows extend away from the high ground of the province centre towards lower ground near the edges. In part due to its geometry, the MBP is situated within four river catchments; only surface water landing in the east flows into the Burdekin River. Regionally, groundwater migrates through the basalts of the MBP from the central high ground radially towards the edges. Direct groundwater discharge from the MBP basalts into the Burdekin River has been shown in this project. Similarly to the NBP, groundwater is also known to discharge to numerous springs and surface watercourses in the MBP. Water levels in many bores responded to major rainfall events. Responses ranged from a change in declining hydrograph slope to a water level increase of ~6.8 m in the southeast. While some responses could have been induced by loading, the extent of water level rise showed that others were clearly caused by recharge. No nested monitoring locations were installed for the EFTF project, so vertical head gradients are currently unknown. Although there are numerous registered extraction bores in the MBP, groundwater level response to pumping was only definitively identified in the east in bore RN12010016. However, several registered bores with high estimated yields have been installed in the northeast since EFTF fieldwork completion. It is possible that these higher yielding extraction bores may induce visible drawdown in monitoring bores in the future. Their high estimated yields may be associated with lava tubes; features not reported in the literature reviewed for this project for the NBP, but identified at surface and potentially in several Queensland Government bores drilled in the MBP. Conclusions and recommendations The Upper Burdekin Groundwater Project has provided abundant information on various aspects of the hydrogeology of the Nulla and McBride basalt provinces. General groundwater flow processes are understood at a regional scale for the EFTF monitoring period, but more detailed investigations and longer term monitoring are required to fully evaluate local conditions. One of the main observations of this study are the long term groundwater level declines in both the NBP and MBP following the 2010-2011 La Niña-associated floods. Groundwater levels are yet to reduce to pre-flood elevations in places, showing that the EFTF monitoring period represents only a small fraction of a much longer-functioning, dynamic groundwater system. It is unclear what, if any, contribution groundwater extraction has made to regional water level declines. Numerous correlations were assessed between groundwater hydrograph characteristics and potentially influencing factors, but the results were mostly inconclusive. There is uncertainty in hydraulic connectivity across lava flow boundaries and between intra-lava flow aquifers. Although interesting groundwater processes were identified at many bores, at the current bore spacing it is not generally possible to interpolate between locations with any certainty. Knowledge gaps and suggestions for further investigation are recorded in Section 5 of the report. The gaps identified should assist planning of future work to inform: - Further characterisation of groundwater resources. - Protection of groundwater dependent ecosystems. - Appropriate groundwater resource management.

HiQGA is a general purpose software package for spatial statistical inference, geophysical forward modeling, Bayesian inference and inversion (both deterministic and probabilistic). It includes readily usable geophysical forward operators for airborne electromagnetics (AEM), controlled-source electromagnetics (CSEM) and magnetotellurics (MT). Physics-independent inversion frameworks are provided for probabilistic reversible-jump Markov chain Monte Carlo (rj-MCMC) inversions, with models parametrised by Gaussian processes (Ray and Myer, 2019), as well as deterministic inversions with an "Occam inversion" framework (Constable et al., 1987). In development software for EFTF since 2020

The Geological Survey of South Australia (GSSA) designed the Gawler Craton Airborne Survey (GCAS) to provide high resolution magnetic, gamma-ray and elevation data covering the northern portion of the Gawler Craton. In total, 1.66 million line km were planned over an area of 295,000 km2 , covering approximately 30% of the state of South Australia. The survey design of 200 m spaced lines at a ground clearance of 60 m can be compared with the design of existing regional surveys which generally employed 400 m line spacing and a ground clearance of 80 m. The new survey design results in ~2 x the data coverage and ~25% closer to the ground when compared to previous standards for regional surveys in South Australia. Due to the enormous scale of the survey, the data were acquired using four contractors who employed ten systems to fly the sixteen blocks. To standardise the data from the multitude of systems, Geoscience Australia (GA) employed a comprehensive set of technical specifications. As part of these specifications the contractors were required to fly each of the ten systems over a series of test lines termed the “Whyalla Test Lines” (Whyalla). The final GCAS data provide truly impressive high resolution regional scale products. These will allow more detailed geological interpretation of the prospective Gawler Craton. Survey blocks available for download include: Tallaringa North, block 1A Tallaringa South, block 1B Coober Pedy West, block 8A Billa Kalina, block 8B Childara, block 9A Lake Eyre, block 10 The following grids are available in this download: • Laser-derived digital elevation model grids (m). Height relative to the Australian Height Datum. • Radar-derived digital elevation model grids (m). Height relative to the Australian Height Datum. • Total magnetic intensity grid (nT). • Total magnetic intensity grid with variable reduction to the pole applied (nT). • Total magnetic intensity grid with variable reduction to the pole and first vertical derivative applied (nT/m). • Dose rate concentration grid (nGy/hr). • Potassium concentration grid (%). • Thorium concentration grid (ppm). • Uranium concentration grid (ppm). • NASVD processed dose rate concentration grid (nGy/hr). • NASVD processed potassium concentration grid (%). • NASVD processed thorium concentration grid (ppm). • NASVD processed uranium concentration grid (ppm). The following point located data are available in this download: • Elevation. Height relative to the Australian Height Datum. Datum: GDA94 • Total Magnetic Intensity. Datum: GDA94 • Radiometrics. Datum: GDA94

<p>The Geological Survey of South Australia commissioned the Gawler Craton Airborne Survey (GCAS) as part of the PACE Copper initiative. The airborne geophysical survey was flown over parts of the Gawler Craton in South Australia. The program was designed to capture new baseline geoscientific data to provide further information on the geological context and setting of the area for mineral systems (http://energymining.sa.gov.au/minerals/geoscience/pace_copper/gawler_craton_airborne_survey). <p>The survey design of 200 m spaced lines at a ground clearance of 60 m can be compared with the design of previous regional surveys which generally employed 400 m line spacing and a ground clearance of 80 m. The new survey design results in ~2 x the data coverage and ~25% closer to the ground when compared to previous standards for regional surveys in South Australia. <p>Survey blocks available for download include: <p>Streaky Bay, block 5 <p>Gairdner, block 6A <p>Spencer, block 7 <p>Kingoonya, block 9B <p>The following grids are available in this download: <p>• Laser-derived digital elevation model grids (m). Height relative to the Australian Height Datum. <p>• Radar-derived digital elevation model grids (m). Height relative to the Australian Height Datum. <p>• Total magnetic intensity grid (nT). <p>• Total magnetic intensity grid with variable reduction to the pole applied (nT). <p>• Total magnetic intensity grid with variable reduction to the pole and first vertical derivative applied (nT/m). <p>• Dose rate concentration grid (nGy/hr). <p>• Potassium concentration grid (%). <p>• Thorium concentration grid (ppm). <p>• Uranium concentration grid (ppm). <p>• NASVD processed dose rate concentration grid (nGy/hr). <p>• NASVD processed potassium concentration grid (%). <p>• NASVD processed thorium concentration grid (ppm). <p>• NASVD processed uranium concentration grid (ppm). <p>The following point located data are available in this download: <p>• Elevation. Height relative to the Australian Height Datum. Datum: GDA94 <p>• Total Magnetic Intensity. Datum: GDA94 <p>• Radiometrics. Datum: GDA94

This context report is for the Upper Darling River Floodplain module, which represents the easternmost ‘arm’ of the Exploring for the Future Darling-Curnamona-Delamerian project area within New South Wales. The document provides a summarised state of knowledge regarding the geography, geology, hydrology, hydrogeology and water management of the Upper Darling region. It provides baseline information relevant to understanding the regional context of water resources, with relevance to forward planning and prioritisation of further investigations. As such, this report largely represents a collation of existing information (literature review) for the Upper Darling region, with limited new information (e.g., airborne electromagnetic survey results, preliminary review of existing bore data) being presented.

Presentation to Australian Research Council (ARC) Training Centre for Data Analytics in Resources and Environment (DARE) Symposium (17 February 2023, University of Sydney) demonstrating use of uncertainty in hydrogeophysical applications as part of the Upper Darling River Floodplain EFTF project.

<div>The groundwater and surface water systems associated with the Upper Darling River Floodplain (UDF) in arid northwest New South Wales form part of the Murray-Darling Basin drainage system, which hosts 40% of Australia’s agricultural production. Increasing water use demands and a changing regional climate are affecting hydrological systems, and consequently impacting the quality and quantity of water availability to communities, industries and the environment.</div><div>As part of the Australian Government’s Exploring for the Future program, the UDF project is working in collaboration with State partners to collect and integrate new data and information with existing hydrogeological knowledge. The goal is to provide analyses and products that assist water managers to increase water security in the region, with a focus on groundwater resources. </div><div>As part of this project we are assessing the occurrence of, and geological controls on, potable water resources within the Darling Alluvium (DA), which comprises unconsolidated sediments (<140 m thick) associated with the modern and paleo-Darling River. The DA’s relationship to the underlying Eromanga, Surat (Great Artesian Basin) and Murray basins is also important, particularly in the context of potential groundwater sources or sinks, and connection between low and high quality groundwater resources. At least one major fault system is known to influence groundwater flow paths and control groundwater-surface water interaction.</div><div>Data collection across the project area has commenced, with an airborne electromagnetic (AEM) survey already complete, and new geophysical, hydrochemical and hydrodynamic data being acquired. Preliminary interpretation of the new AEM data in conjunction with existing geological and hydrogeological information has already revealed the major paths and geometries of the paleo-Darling River, given important insights into potential fault controls on groundwater flow paths, and shown variation in the thickness, distribution and character of the DA, which has direct implications for groundwater–surface water connectivity.</div><div><br></div>

Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. The name ‘Birrindudu Basin’ was first introduced by Blake et al. (1975) and Sweet (1977) for a succession of clastic sedimentary rocks and carbonates, originally considered to be Paleoproterozoic to Neoproterozoic in age, and overlain by the Neoproterozoic Victoria Basin (Dunster et al., 2000), formerly known as the Victoria River Basin (see Sweet, 1977).

Fresh groundwater stored in Australian coastal aquifers is an important resource for humans and the natural environment. Many Australian coastal aquifers are vulnerable to seawater intrusion (SWI)—the landward encroachment of sea water into coastal aquifers—which can significantly degrade water quality and reduce freshwater availability. The increasing demands for fresh water in coastal areas and the anticipated impacts of climate change (such as sea-level rise and variations in rainfall recharge) may result in increases in the incidence and severity of SWI. Comprehensive investigations of SWI are relatively uncommon and the extent of monitoring and investigations specific to SWI are highly variable across the nation. In response to the threat posed by SWI, Geoscience Australia and the National Centre for Groundwater Research and Training, in collaboration with state and territory water agencies, undertook a national-scale assessment of the vulnerability of coastal aquifers to SWI. This assessment identified the coastal groundwater resources that are most vulnerable to SWI, including future consequences of over-extraction, sea-level rise, and recharge–discharge variations associated with climate change. The study focused on assessing the vulnerability of coastal aquifers to the landward migration of the freshwater–saltwater interface, rather than surface waterbodies.

The Great Artesian Basin (GAB) covers one fifth of Australia and is the largest groundwater ‘basin’ on the continent. Groundwater from the GAB is a vital resource for pastoral, agricultural and extractive industries, underpinning at least $12.8 billion in economic activity annually, as well as providing town water supplies and supporting environmental and cultural values. The Australian Government, through the National Water Infrastructure Development Fund – Expansion, commissioned Geoscience Australia to undertake the project ‘Assessing the Status of Groundwater in the Great Artesian Basin’. A key deliverable of this project is a water balance (for 2019) encompassing the main aquifers of the GAB. To facilitate this outcome, a range of tools and techniques to assist in the development of improved hydrogeological conceptualisations of the GAB have been developed and assessed. This report presents the results of investigations from a pilot study area in the northern Surat Basin, Queensland, with components of the work extending into the wider GAB. The results demonstrate that the application of existing and new geoscientific data and technologies has the potential to further improve our understanding of the GAB hydrogeological system thus supporting the responsible management of basin water resources. Groundwater recharge potential within the GAB intake beds has been investigated using techniques that consider variations in physical and environmental characteristics. Empirical modelling assessing deep drainage as a recharge proxy suggests that, with isolated exceptions, diffuse recharge potential is generally low across most of the study area. The spatial variability in recharge potential can assist in the interpretation and/or interpolation of estimates derived from other techniques, such as chloride mass balance. The results of machine learning modelling suggest that further work is needed to better constrain uncertainty in input and training datasets, and in the development of robust translations of outputs to hydrogeologically meaningful products. The chloride mass balance (CMB) method remains the most appropriate tool for estimating long-term mean gross recharge to GAB aquifers in the northern Surat Basin. New upscaling methods provide significant improvements for mapping regional scale groundwater recharge rates and quantifying uncertainties associated with these estimates. Application of multiple techniques to the assessment of groundwater flow and recharge processes is necessary to complement CMB recharge estimates, and reduce associated uncertainty. Analysis of groundwater environmental tracers are recommended for constraining CMB recharge rates. Integrated geological assessments using airborne electromagnetic data in conjunction with other geophysical and geological data (e.g., reflection seismic, wells) are effective at characterising aquifer architecture to better understand geometry, flow pathways and structural controls relevant to recharge and connectivity at local to regional scales. Significant effort has gone into updating the regional geological framework at the whole-of-GAB scale, combining legacy and new data with recent knowledge to revise the hydrogeological conceptualisation of the GAB. This assists in constraining interpretations of regional depositional architecture and lithological heterogeneity within hydrogeological units, particularly those properties that influence groundwater storage and flux. Assessment of lateral and vertical heterogeneity of hydraulic properties within and between aquifers and aquitards in the northern Surat Basin has refined our understanding of potential groundwater connectivity and compartmentalisation. This study provides an improved hydrogeological framework to support revised water balance estimates for the GAB, and insights into potential recharge variability that may impact those input components. Targeted examples from the northern Surat Basin demonstrate the application of the techniques and tools employed, including methods to reduce uncertainty. The outcomes of this work underpin a revised hydrogeological conceptualisation for the GAB, a standardised basis for establishing future investigations, and a framework for more informed water management decision-making.