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.

Knowledge of the nature of buildings within CBD areas is fundamental to a broad range of decision making processes, including planning, emergency management and the mitigation of the impact of natural hazards. To support these activities, Geoscience Australia has developed a building information system called the National Exposure Information System (NEXIS) which provides information on buildings across Australia. Most of the building level information in NEXIS is statistically derived, but efforts are being made to include more detailed information on the nature of individual buildings, particularly in CBD areas. This is being achieved in Brisbane through field survey work.

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

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.

This report presents groundwater levels results 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 describes a data release of water levels measured in monitoring bores in both provinces by Geoscience Australia during the EFTF project. It includes: - A full description of how water levels in metres relative to Australian Height Datum (m AHD; where zero m AHD is an approximation of mean sea level) were calculated from manual dips and electronic dataloggers for this project. - A series of tables in Appendix A containing sufficient information for each bore and datalogger file to reproduce the water levels reported in Appendix B and Appendix C. - A series of hydrographs in Appendix B showing how water levels (in m AHD) interpreted from manual dips and datalogger files varied during the EFTF project. - A series of electronic files in Appendix C that include (i) Data files from dataloggers in CSV file format that can be used with the information contained in this data release to regenerate the water levels shown on hydrographs in Appendix B, and (ii) Data files in CSV file format reporting the final water levels used to generate the hydrographs in Appendix B. This data release report does not include hydrograph interpretation, which is undertaken in detail in: Cook, S. B. & Ransley, T. R., 2020. Exploring for the Future—Groundwater level interpretations for the McBride and Nulla basalt provinces: Upper Burdekin region, North Queensland. Geoscience Australia, Canberra, https://pid.geoscience.gov.au/dataset/ga/135439.

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.

As part of the Great Artesian Basin (GAB) Project a pilot study was conducted in the northern Surat Basin, Queensland, to test the ability of existing and new geoscientific data and technologies to further improve our understanding of hydrogeological systems within the GAB, in order to support responsible management of basin water resources. This report presents selected examples from the preliminary interpretation of modelled airborne electromagnetic (AEM) data acquired as part of this pilot study. The examples are selected to highlight key observations from the AEM with potential relevance to groundwater recharge and connectivity. Previous investigations in the northern Surat Basin have suggested that diffuse groundwater recharge rates are generally low (in the order of only a few millimetres per year) across large areas of the GAB intake beds—outcropping geological units which represent a pathway for rainfall to enter the aquifers—and that, within key aquifer units, recharge rates and volumes can be heterogeneous. Spatial variability in AEM conductivity responses is identified across different parts of the northern Surat Basin, including within the key Hutton Sandstone aquifer. Consistent with findings from other studies, this variability is interpreted as potential lithological heterogeneity, which may contribute to reduced volumes of groundwater entering the deeper aquifer. The influence of geological structure on aquifer geometry is also examined. Larger structural zones are seen to influence both pre- and post-depositional architecture, including the presence, thickness and dip of hydrogeological units (or parts thereof). Folds and faults within the Surat Basin sequences are, in places, seen as potential groundwater divides which may contribute to compartmentalisation of aquifers. Discrete faults have the potential to influence inter-aquifer connectivity. The examples presented here demonstrate the utility of AEM models, in conjunction with other appropriate geophysical and geological data, for characterising potential recharge areas and pathways within the main GAB aquifer units, by helping to better define aquifer geometry, lithological heterogeneity and possible structural controls. Such assessments have the potential to further improve our understanding of groundwater recharge and flow path variability at local to regional scales. Acquisition of broader AEM data coverage across groundwater recharge areas, along with complementary geophysical, geological and hydrogeological data, would further assist in quantifying recharge variability, facilitating revised water balance estimates for the basin and thereby supporting GAB water resource management and policy decision-making.

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).

This activity introduces the concepts of lava viscosity and influence on volcanic cone shape. The download includes background information for teachers and an activity sheet for students. The activity involves making lava slime and racing this down a slope. Participants are asked to predict how lava viscosity might influence volcanic shape (a hypothesis) and then observe what does happen and relate this to the natural environment.

The magnetotelluric (MT) method is increasingly being applied to map tectonic architecture and mineral systems. Under the Exploring for the Future (EFTF) program, Geoscience Australia has invested significantly in the collection of new MT data. The science outputs from these data are underpinned by an open-source data analysis and visualisation software package called MTPy. MTPy started at the University of Adelaide as a means to share academic code among the MT community. Under EFTF, we have applied software engineering best practices to the code base, including adding automated documentation and unit testing, code refactoring, workshop tutorial materials and detailed installation instructions. New functionality has been developed, targeted to support EFTF-related products, and includes data analysis and visualisation. Significant development has focused on modules to work with 3D MT inversions, including capability to export to commonly used software such as Gocad and ArcGIS. This export capability has been particularly important in supporting integration of resistivity models with other EFTF datasets. The increased functionality, and improvements to code quality and usability, have directly supported the EFTF program and assisted with uptake of MTPy among the international MT community. <b>Citation:</b> Kirkby, A.L., Zhang, F., Peacock, J., Hassan, R. and Duan, J., 2020. Development of the open-source MTPy package for magnetotelluric data analysis and visualisation. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.