This report presents a summary of the groundwater hydrochemistry data release from the Alice Springs project conducted as part of Exploring for the Future (EFTF). This data release records the groundwater sample collection methods and hydrochemistry and isotope data from monitoring bores in the Alice Springs project area, Northern Territory (NT). The Alice Springs project is a collaborative study between Geoscience Australia and the NT Government. Hydrochemistry and isotope data were collected from existing and newly drilled bores in the Alice Springs area.

This service provides access to hydrochemistry data (groundwater and surface water analyses) obtained from water samples collected from Australian water bores or field sites.

Poster prepared for International Association of Hydrogeologists Congress 2013 Surface-groundwater interactions are often poorly understood. This is particularly true of many floodplain landscapes in Australia, where there is limited mapping of recharge and discharge zones along the major river systems, and only generalised quantification of hydrological fluxes based on widely spaced surface gauging stations. This is compounded by a lack of temporal data, with poor understanding of how surface-groundwater interactions change under different rainfall, river flow and flood regimes. In this study, high resolution LiDAR, in-river sonar, and airborne electromagnetic (AEM) datasets (validated by drilling) have been integrated to produce detailed 3-dimensional mapping that combines surface geomorphology and hydrogeology. This mapping enables potential recharge zones in the river and adjacent landscape to be identified and assessed under different flow regimes. These potential recharge zones and groundwater flow pathways were then compared against the spatial distribution of discontinuities in near-surface and deeper aquitard layers derived from the AEM interpretation. These 3D mapping constructs provide a framework for considering groundwater processes. Hydrochemistry data, allied with hydraulic data from a bore monitoring network, demonstrate the importance of recharge during significant flood events. In many places, the AEM data also affirm the spatial association between fresher groundwater resources and sites of river and floodplain leakage. At a more localised scale, hydrogeochemical data allows discrimination of lateral and vertical fluxes. Overall, this integrated approach provides an important conceptual framework to constrain hydrogeological modelling, and assessments of sustainable yield. The constructs are also invaluable in targeting and assessing managed aquifer recharge (MAR) options.

The greater Eromanga Basin is an intracratonic Mesozoic basin covering an area of approximately 2,000,000 km2 in central and eastern Australia. The greater Eromanga Basin encompasses three correlated basins: the Eromanga Basin (central and western regions), Surat Basin (eastern region) and the Carpentaria Basin (northern region). The greater Eromanga Basin hosts Australia's largest known resources of groundwater as well as major onshore hydrocarbon resources, including significant coal bed methane (CBM) that has been discovered in recent years, and also contains extensive hot-sedimentary aquifer geothermal energy systems. Additionally, the basin has potential as a greenhouse gas sequestration site and will likely play a key role in securing Australia's energy future. Finally, although no major metallic mineral deposits are currently known in the greater Eromanga Basin, there is significant potential for undiscovered uranium mineralisation. A 3D geological map has been constructed for the greater Eromanga Basin using publicly available datasets. These are principally drilling datasets (i.e. water bores; mineral and petroleum exploration wells) and the 1:1,000,000 scale Surface Geology Map of Australia. Geophysical wireline logs, hydrochemistry, radiometrics, magnetic and gravity datasets were also integrated into the 3D geological map. This study has highlighted the potential of the southwest margin of the Eromanga Basin and the Euroka arch region to contain sandstone-hosted uranium mineral systems. The report demonstrates how incorporating disparate datasets in a 3D geological map can generate an integrated mapping solution with diverse applications: 1. Provide new insights into the geology and geodynamic evolution of the basin. 2. Identify hydrocarbon resource plays. 3. Assess the basin's mineral potential (e.g., sandstone-hosted uranium mineral systems). 4. Assess the basin's geothermal potential (e.g., hot-sedimentary aquifer geothermal systems). 5. Provide resource management information (e.g., groundwater). 6. Identify potential contaminants in groundwater.

Grids representing chemical parameter concentrations and isotopic variations in groundwater in the Great Artesian Basin for the following aquifers: Adori Sandstone; Cadna-owie - Hooray and equivalents; Hutton Sandstone and Winton-Mackunda Formation. (Note: Stable isotope carbon variations, Carbon-14 variation and Chlorine ratios produced for the Cadna-owie-Hooray and equivalents only) Hydrochemical parameters and isotopic variations mapped are: - Total dissolved solids (TDS) (mg/L) (adori_tds.txt, cad-hoor_tds.txt, hutton_tds.txt, wint-mack_tds.txt) - Total alkalinity (mg/L CaCO3) (adori_alk, cad-hoor_alk, hutton_alk, wint-mack_alk) - Sulphate (mg/L) ( adori_so4, cad-hoor_so4, hutton_so4, wint-mack_so4) - Fluoride (mg/L) ( adori_flu, cad-hoor_flu, hutton_flu, wint-mack_flu) - Sodium adsorption ratio (adori_sar, cad-hoor_sar, hutton_sar, wint-mack_sar) - Stable carbon isotope variations (d13C % PDB) ( tp-rs_13c_ch) - Carbon-14 variation (14C pMC) ( tp-rs_14c_ch) - Chlorine-36 to Chloride ratio ( t-rs_36clr_ch) Grid cell size (X, Y) = 0.015 DD, 0.015 DD. These GIS data sets were produced for the Great Artesian Basin Water Resource Assessment and used in Figures 8.2, 8.4, 8.5, 8.6, 8.8, 8.10, 8.12 and 8.13 of Ransley TR and Smerdon BD (eds) (2012) Hydrostratigraphy, hydrogeology and system conceptualisation of the Great Artesian Basin. A technical report to the Australian Government from the CSIRO Great Artesian Basin Water Resource Assessment. CSIRO Water for a Healthy Country Flagship, Australia. This dataset and associated metadata can be obtained from www.ga.gov.au, using catalogue number 76942.

This report presents key results from the Ti Tree Basin project completed 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. Hydrogeological data acquisition and interpretation in the Ti Tree Basin, Northern Territory, was undertaken by Geoscience Australia as part of the EFTF Program. Located ~150 km north of Alice Springs, the Cenozoic basin hosts regionally significant groundwater resources, relied upon by communities, irrigators and pastoralists. Although the basin has been extensively studied over several decades, critical information gaps still remain, particularly for the deep groundwater system (>80 m depth). Work combining new geophysical and hydrochemical data with pre-existing datasets has revealed a more complex basin hydrogeology. Mapping based on airborne electromagnetics (AEM) has identified complex structural controls on the distribution of the deep basin sequence, with consequences for aquifer compartmentalisation, regional groundwater flow and aquifer connectivity. The mapping also shows where the basin sediments are much thicker than previously drilled. The hydrochemical assessment highlighted the complexity in groundwater recharge mechanisms, showing that the rainfall threshold for effective recharge and the role of evaporation are not consistent across the floodout zones in the basin. The EFTF products provide guidance for future hydrogeological investigations. In particular, there is evidence from historic drilling for potentially useful groundwater resources in the underexplored deep basin sequence. The EFTF program has expanded the knowledge base and datasets for the Ti Tree Basin. Collectively, these are valuable assets not just for basin groundwater management but also for the broader understanding of groundwater resources and processes in central Australia.

This report presents key results of the Ti Tree Basin study completed 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. As part of EFTF, Geoscience Australia undertook an assessment of available and new hydrochemical data collected in the Ti Tree Basin, Northern Territory. The basin is one of the four water control districts within the Southern Stuart Corridor Project area. Communities, irrigation farms and pastoral stations in the basin rely on groundwater, and extensive groundwater sampling and hydrochemical investigations have been undertaken over the past 50 years. An opportunity was recognised to collate and interpret the existing data, supplemented by new EFTF data, not only to add value to the understanding of groundwater processes in the basin itself but also to provide a useful knowledge base for other groundwater resources in the region that are poorly understood. This study largely relied on the available groundwater analysis data from the Northern Territory Department of Environment and Natural Resources database, supplemented by publicly available analyses from other sampling campaigns, including the EFTF, totaling 1913 groundwater samples across the district. The key findings of the study are: • The hydrochemistry data, particularly on salinity (total dissolved solids (TDS)), ion ratios (e.g. HCO3/Cl, Cl/(Cl+HCO3), Cl/(Cl+HCO3+SO4), Na/Cl) and radiocarbon (14C) could be used to map the three major recharge areas for the basin—the floodout of the Woodforde River to the west, the floodout of Allungra Creek in the basin centre, and the eastern basin margin. This is consistent with the current accepted interpretation that recharge is dominated by episodic run-on and infiltration in drainage floodout areas, driven by intense rainfall events that generate runoff in upland basement headwaters and ephemeral flows in basin creeks. There are no hydrochemical indicators of recharge in the vicinity of the channelised reaches of the basin creeks (i.e. both Woodforde River and Allungra Creek), located upstream of the floodouts. • From a groundwater resource perspective, the Allungra Creek floodout has broadly the best combination of low-salinity groundwater (median TDS = 740 mg/L) and bore yield statistics (median = 10 L/s). The Woodforde River floodout also has areas with high-yielding bores (>10 L/s) of fresh groundwater (<1000 mg/L), with the borehole distribution suggesting that the fresh groundwater resource is significantly more extensive to the west of the river than that previously mapped. The eastern basin margin generally has low-salinity groundwater (median TDS = 775 mg/L) but lower bore yields (median = 4.4 L/s). • There are differences in the recharge characteristics of the three floodout areas, due to differences in drainage catchments and floodout hydrogeology. The Woodforde River floodout has the most depleted stable isotopes, interpreted to be due to a higher rainfall/runoff threshold for recharge (>150 mm/month). It also has the largest isotopic range and the best δ18O-δ2H linear regression, suggesting the most influence of evaporation, such as a longer period of surface water ponding. In comparison, the stable isotope signature for Allungra Creek groundwaters suggests a lower rainfall/runoff threshold for recharge (>100 mm/month) and low evaporative influence, hence relatively rapid infiltration. This is also inferred to be the case for the low-salinity eastern basin margin groundwaters. For both Woodforde River and Allungra Creek, modern recharge is indicated by groundwaters with high radiocarbon activity (14C percent modern carbon (pMC) >70). For the eastern basin margin, radiocarbon activity is low to moderate (14C pMC 20–50). This is interpreted to reflect a longer travel time in the unsaturated zone. • In the floodout areas, the dominant hydrogeochemical process relating to the fresh groundwater is water–rock interactions. Groundwater tends to be the least evolved Ca(Mg)-HCO3 or transitional Na(K)-HCO3 water type, according to Chadha plots. Zones of prevalence of carbonate-gypsum dissolution or Na-silicate weathering could be mapped using indicators such as cation chloride ratio. Ion exchange is also a likely process in these fresh groundwaters, as inferred from chloro-alkaline indices. • Groundwater salinity is higher away from the floodout areas. This increased salinity is due to evapotranspirative concentration in addition to water–rock interactions, as inferred from ion ratios, including Cl/Br. Stable isotopes indicate that transpiration of groundwater by vegetation accessing the watertable, rather than direct evaporation, is the dominant process in these areas. This process is particularly evident in the Wilora Palaeochannel, the northern extension of the basin, which generally has the highest groundwater salinities (median TDS = 1575 mg/L), the lowest bore yields (median = 1.9 L/s) and the greatest prevalence of shallow watertables (<15 m). With higher salinities, groundwaters tend to be the evolved Ca(Mg)-Cl(SO4) and Na(K)-Cl(SO4) water types and potentially influenced by reverse ion exchange processes. • Mountain-front recharge has previously been proposed as an additional recharge mechanism, notably near the southern basin margin. Although sampling is limited in this area, hydrochemical indicators such as low HCO3/Cl, high Na/Cl and evolved Na(K)-Cl(SO4) water type suggests that active recharge is not significant. The watertable is deep along the southern basin margin (>50 m), so groundwater chemistry can be strongly influenced by processes during downward infiltration through a thick unsaturated zone. • Limited sampling of deeper bores (>80 m), potentially in the Hale Formation, generally have the characteristics of being more saline and lower yielding compared to bores in the shallow groundwater resource (particularly from 40 m to 80 m). However, there are deep bores with good yields of fresh groundwater; of 57 bores in the basin with interval depths exceeding 80 m, eight (14%) have the combination of yield >5 L/s and salinity <1000 mg/L. The deeper groundwaters are typically Ca(Mg)-Cl(SO4) and Na(K)-Cl(SO4) water types, with the latter, more evolved, water type dominating at depths >120 m. There are very few stable isotope analyses for the deeper groundwaters, but these are within the isotopic range for the shallow groundwaters in the same area, suggesting similarity in recharge processes and a degree of aquifer connectivity. Likewise, there are very few radiocarbon analyses for deeper groundwaters (depth >60 m), but these consistently show low 14C activity (pMC <40). The higher salinities, evolved water types and low 14C activity reflect longer residence times in the deeper groundwater system. The study highlighted that floodout recharge, involving episodic flow of basin creeks from headwater catchments, is the most dominant mechanism, rather than direct infiltration from large rainfall events. The study also identified that recharge characteristics, particularly the rainfall threshold for effective recharge and the role of evaporation, are not consistent across the floodout zones in the basin. This likely reflects differences in upland catchment size and geology, as well as floodout landform and hydrogeology. The study also highlighted the importance of groundwater-dependent vegetation in the basin, with dominance of transpiration of groundwater rather than direct evaporation. The groundwater hydrochemistry datasets and interpretation maps can support informed water management decisions within the basin. For example, improved understanding of the spatial and temporal distribution of recharge is not only needed for defining groundwater extraction limits but also used in strategies such as managed aquifer recharge. The EFTF work adds to the knowledge base and datasets that have developed over decades for the Ti Tree Basin, which are also valuable assets for broader understanding of groundwater resources in central Australia.

<div>This report presents key results from the Upper Darling River Floodplain groundwater study conducted as part of the Exploring for the Future (EFTF) program in north-western New South Wales. The Australian Government funded EFTF program aimed to improve understanding of potential mineral, energy, and groundwater resources in priority areas for each resource.</div><div><br></div><div>The Upper Darling River Floodplain study area is located in semi-arid zone northwest New South Wales is characterised by communities facing critical water shortages and water quality issues, along with ecosystem degradation. As such, there is an imperative to improve our understanding of groundwater systems including the processes of inter-aquifer and groundwater-surface water connectivity. The key interest is in the fresh and saline groundwater systems within alluvium deposited by the Darling River (the Darling alluvium - DA) which comprises sediment sequences from 30 m to 140 m thick beneath the present-day floodplain.</div><div><br></div><div>The study acquired airborne, surface and borehole geophysical data plus hydrochemical data, and compiled geological, hydrometric, and remote sensing datasets. The integration of airborne electromagnetic (AEM) data with supporting datasets including surface and borehole magnetic resonance, borehole induction conductivity and gamma, and hydrochemistry data has allowed unprecedented, high resolution delineation of interpreted low salinity groundwater resources within the alluvium and highly saline aquifers which pose salination risk to both the river and fresher groundwater. Improved delineation of the palaeovalley architecture using AEM, seismic, and borehole datasets has permitted interpretation of the bedrock topography forming the base of the palaeovalley, and which has influenced sediment deposition and the present-day groundwater system pathways and gradients.</div><div><br></div><div>The integrated assessment demonstrates that the alluvial groundwater systems within the study area can be sub-divided on the basis of groundwater system characteristics relevant to water resource availability and management. Broadly, the northern part of the study area has low permeability stratigraphy underlying the river and a generally upward groundwater gradient resulting in limited zone of freshwater ingress into the alluvium around the river. A bedrock high south of Bourke partially restricts groundwater flow and forces saline groundwater from deeper in the alluvium to the surface in the vicinity of the Upper Darling salt interception scheme. From approximately Tilpa to Wilcannia, sufficiently permeable stratigraphy in hydraulic connection with the river and a negligible upward groundwater gradient allows recharge from the river, creating significant freshwater zones around the river within the alluvium.</div><div><br></div><div>Hydrometric and hydrochemical tracer data demonstrate that the alluvial groundwater systems are highly coupled with the rivers. Results support the conceptual understanding that bank-exchange processes and overbank floods associated with higher river flows are the primary recharge mechanism for the lower salinity groundwater within the alluvium. When river levels drop, tracers indicative of groundwater discharge confirm that groundwater contributes significant baseflow to the river. Analysis of groundwater levels and surface water discharge indicates that the previously identified declining trends in river discharge are likely to produce the significant decline in groundwater pressure observed across the unconfined aquifer within the alluvium. Improved quantification and prediction of groundwater-surface water connectivity, water level and flux is considered a high priority for both the Darling River and the wider Murray–Darling Basin. This information will assist in understanding and managing water resource availability in these highly connected systems, and enhance knowledge regarding cultural values and groundwater dependent ecosystems (GDEs).</div><div><br></div><div>This study identifies several aquifers containing groundwater of potentially suitable quality for a range of applications in the south of the study area between Wilcannia and Tilpa and assessed the geological and hydrological processes controlling their distribution and occurrence. Potential risks associated with the use of this groundwater, such as unsustainable extraction, impacts on GDEs, and saline intrusion into aquifers or the river, are outside the scope of this work and have not been quantified.</div>

This web service provides access to geological, hydrogeological and hydrochemical digital datasets that have been published by Geoscience Australia for the Great Artesian Basin (GAB).

Geoscience Australia and its predecessors have analysed hydrochemistry of water sampled from boreholes (both pore water and groundwater), surface features, and rainwater. Sampling was undertaken during drilling or monitoring projects, and this dataset represents a significant subset of stored analyses. Water chemistry including isotopic data is essential to better understand groundwater origins, ages and dynamics, processes such as recharge and inter-aquifer connectivity and for informing conceptual and numerical groundwater models. This GA dataset underpins a nationally consistent data delivery tool and web-based mapping to visualise, analyse and download groundwater chemistry and environmental isotope data. This dataset is a spatially-enabled groundwater hydrochemistry database based on hydrochemistry data from projects completed in Geoscience Australia. The database includes information on physical-chemical parameters (EC, pH, redox potential, dissolved oxygen), major and minor ions, trace elements, nutrients, pesticides, isotopes and organic chemicals. Basic calculations for piper plots colours are derived from Peeters, 2013 - A Background Color Scheme for Piper Plots to Spatially Visualize Hydrochemical Patterns - Groundwater, Volume 52(1) <https://doi.org/10.1111/gwat.12118>. Upon loading the data to the database, all hydrochemistry data are assessed for reliability using Quality Assurance/Quality Control procedures and all datasets were standardised. This data is made accessible with open geospatial consortium (OGC) web services and is discoverable via the Geoscience Australia Portal (<a href="https://portal.ga.gov.au/">https://portal.ga.gov.au/</a>). This dataset is published with the permission of the CEO, Geoscience Australia.