AEM
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The Broken Hill Managed Aquifer Recharge (BHMAR) project is part of a larger strategic effort aimed at securing Broken Hill's water supply and identifying significant water-saving measures for the Darling River system. Hydrogeological investigations to rapidly identify and assess potential MAR targets and groundwater resources over a large area (>7,500 km2), included acquisition of an airborne electromagnetics (AEM) survey, a 7.5 km drilling program (100 sonic and rotary mud holes), and complementary field and laboratory hydrogeochemical investigations. In this study, AEM mapping validated by drilling has identified significant groundwater resources and potential MAR targets within shallow unconsolidated Pliocene sediments at relatively shallow depths (25-100m). Pliocene sand aquifers comprise the fluvial Calivil Formation, with the shallow marine Loxton-Parilla Sands restricted to the southernmost part of the area. The Calivil Formation is widely distributed, and has high storage capacity and very high transmissivities (up to 50 l/s), with particularly good aquifers developed in palaeochannels at the confluence of palaeo-river systems. The hydraulic properties make the Calivil Formation aquifer potentially suitable for groundwater extraction and/or MAR injection, with excellent recovery efficiencies predicted. The aquifer is sandwiched between variably thick clay aquitards, and can be characterised as varying from a confined to a 'leaky confined' system. Post-depositional warping, tilting and discrete offsets associated with neotoectonics are also recognised. Entry-level risk assessments were carried out for a number of potential MAR targets, with a pre-commissioning semi-quantitative residual risk assessment carried out for a priority site. Assessment of 12 hazard types included hydrogeological modelling, laboratory column clogging studies and geochemical assessment to assess source water treatment requirements.
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Under the Community Stream Sampling and Salinity Mapping Project, the Australian Government through the Department of Agriculture, Fisheries and Forestry and the Department of Environment and Heritage, acting through Bureau of Rural Sciences, funded an airborne electromagnetic (AEM) survey to provide information in relation to land use questions in selected areas along the River Murray Corridor (RMC). The proposed study areas and major land use issues were identified by the RMC Reference Group at its inception meeting on 26th July, 2006. This report has been prepared to facilitate recommendations on the Lindsay-Wallpolla study area. The work was developed in consultation with the RMC Technical Working Group (TWG) to provide a basis for the RMC Reference Group and other stake holders to understand the value and application of AEM data to the study area. This understanding, combined with the Reference Group's assessment of the final results and taking in account policy and land management issues, will enable the Reference Group to make recommendations to the Australian Government.
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Presently, groundwater, through direct extraction (>30%), and indirectly through replenishing our river systems (>20%), contributes over 50% of Australia's water supplies. Groundwater (and surface water) management in Australia faces intensifying pressures, from population expansion and increasing surface water scarcity in southern Australia posed by extreme drought and future climate change. Recently, and significantly, new additional pressures on groundwater systems have emerged through the rapid expansion of new energy sources (coal seam gas, uranium, geothermal and carbon geo-sequestration) and a rapid expansion of the minerals resource sector (including iron ore). The complexity and conflicts in the nexus between water, new energy, minerals and food and fibre security require innovative approaches in science, management and policy. This is particularly the case in the context of Australia's inherent vulnerability to climate change and the likely emergence of a carbon economy. Quantification of the hydrological cycle and catchment water balances in Australia is limited by a lack of spatial and temporal data. While substantial effort has been put into developing approaches for the mapping and quantification of surface hydrology, resources and processes, significant uncertainty remains in the knowledge of the size of Australian groundwater resources, their locations, rates of recharge, connectivity with surface waters and rates of use or depletion. Recently completed groundwater audits and regional groundwater investigations have made valuable assessments of resources based on limited available data, but have not adequately quantified the large uncertainties in groundwater model predictions and resource assessments, or identified where and what data and knowledge is required to improve these assessments.
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This report summarises the result of a study into seawater intrusion into coastal aquifers in the Northern territory coastal plain using AEM data, down hole geophysics, and bore hole geology carried out by Geoscience Australia on behalf of the National Water Commission and in partnership with NRETAS. The study showed that ground-validated AEM is able to map areas of saline aquifers in the area and differentiate them from bedrock conductors.
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A new Geoscience Australia Magnetic Anomaly Grid Database of Australia (MAGDA) has been developed. This database contains publicly available airborne magnetic grid data for on- and near-offshore Australia. Flight-line magnetic data for each survey have been optimally gridded and the grids matched in one inverse process. New composite grids at 250 m and 400 m grid spacing form the basis of the new fourth edition of the Magnetic Anomaly Map of Australia. Aeromagnetic traverses flown around Australia during 1990 and 1994 are used in both quality control of the grids they intersect, and also to constrain grid merging by forcing grid data, where intersected, to the level of the traverse data. Although matching and merging of many grids into a seamless compilation produces a pleasing result, without obvious short-wavelength artefacts, accurate long wavelength components of crustal origin are more difficult to obtain. Errors in the ?tilt? of individual surveys, due either to older instrumentation, errors in processing, or incomplete core-field removal, can lead to large long wavelength errors when hundreds of surveys are combined across thousands of kilometres. Quantification of the accuracy of long-wavelength components is only possible by comparison with independent datasets. A low-pass filtered composite grid of the Australian region has been compared with CHAMP satellite magnetic data, and shows a considerable improvement in the correlation of long wavelength components compared with the previous edition
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The Capricorn 2013 AEM TEMPEST® survey, conducted as part of the Western Australia Exploration Incentive Scheme and managed by Geoscience Australia on behalf of the Geological Survey of Western Australia (GSWA), is a $2.5 million contribution to the Distal Footprints of Giant Ore Systems: UNCOVER Australia. The Capricorn 2013 AEM survey is Stage 1 of the WA Reconnaissance Airborne Electromagnetic Survey (WARAEM) 2013-20 National Geoscience Agreement project, designed to provide broad-acre, wide line-spacing, airborne electromagnetic (AEM) data over the approximately 70% of the area of Western Australia that is underlain by Precambrian rocks that occur at or within about 300 m of the surface. The Capricorn Orogen is a geologically complex area, the surface expression of which has a surface extent of approximately 240,000 square kilometres (approximately 9 per cent of the area of the State). It is prospective for potentially large discoveries of gold, copper, and other base metals. The Capricorn 2013 AEM TEMPEST data release includes the final contractor supplied (Phase 1) datasets from the TEMPEST® time domain AEM survey as well as a set of GSWA-produced imagery made from the data. The data release package includes: - Point-located, computed B-field EM time-series channel data in ASEG-GDF2 (ASCII) format (also TMI and terrain data) - Point-located computed conductivity and terrain data in ASCII format - Data multiplots (EM x- and z-component time series, CDI sections, TMI, altimeter and monitor channels) in PDF format - CDI stacked sections in PDF format - Gridded data: EM time constant (x- and z-components); selected conductivity-depth slices (in ER Mapper format, 1 km cell size) - Geo-referenced images of gridded EM data in JP2 format - Geo-referenced images of gridded TMI, Ternary Radiometrics, Bouger Gravity and DEM data in JP2 format - Flight path map in ESRI shapefile format - Survey operations report in PDF format - Metadata and License files
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Between the 31st of March 2013 and the 15th of May 2013, Fugro Airborne Surveys Pty. Ltd., (FAS, now known as CGG Aviation (Australia) Pty Ltd) undertook a TEMPEST® airborne electromagnetic and magnetic survey over the South West Coastal Plain and the South Coast areas of Western Australia. There were four separate project areas: (1) Swan Coastal Plain, (2) Scott Coastal Plain, (3) Albany, (4) Esperance. The survey is designed to map groundwater resources and assess aquifer sustainability in four separate areas of southern WA. The survey areas are located in: 1. Esperance: Traverses spaced 300 & 600 metres apart in a north-south direction at 120 metres above ground level totalling 1,133 line km. 2. Albany: Traverses spaced 300 & 600 metres apart in a north-south direction at 120 metres above ground level totalling 2,163 line km. 3. Scott Coastal Plain: Traverses spaced 600 metres apart in a ne-sw direction at 120 metres above ground level totalling 2,980 line km. 4. Swan Coastal Plain: Traverses spaced 600 metres apart in a nw-se direction at 120 metres above ground level totalling 2,303 line km. The total coverage of the survey amounted to 8,579 line kilometres. The survey was flown using a Shorts Skyvan (SC3-200) aircraft, registration VH-WGT, owned and operated by FAS. The survey was commissioned by the Western Australia Department of Water, and was managed by Geoscience Australia. The Survey received funding from the WA Government's Royalties for Regions program to assess, plan and investigate regional water availability in Western Australia. The data release includes the final contractor supplied datasets. The data are available from Geoscience Australia's web site free of charge. Each data package includes: 1. Point-located electromagnetic data with associated position, altimeter, orientation, magnetic, and derived ground elevation data. These data are in ASCII column format with associated ASEG-GDF2 header files. 2. Point-located conductivity estimates derived using the EM Flow® conductivity depth imaging (CDI) algorithm with associated position, altimeter, magnetic, and derived ground elevation data. Data include the conductivity estimate for each 5 m interval and selected depth slices. These data are in ASCII column format with associated ASEG-GDF2 header files. 3. Gridded data, at 60 or 120 m cell size, for the conductivity depth slices derived from the EM Flow® CDI data, magnetics and elevation data in ER Mapper® binary raster grid format with associated header files. 4. Graphical multiplots, in PDF format, for each flight line showing EM Flow® CDI sections and profiles of electromagnetic data, magnetics, monitors, height and orientation data. 5. Operations Report. 6. Metadata and License files.
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Data acquired as part of the Kombolgie VTEMTM Airborne Electromagnetic Survey have been inverted using a layered earth inversion algorithm. Interpretation products have been derived from the inversion results. The inversion results and derived products have been released by Geoscience Australia as a digital data package. The survey was funded under the Australian Government's Onshore Energy Security Program, and was managed and interpreted by Geoscience Australia's Airborne Electromagnetic Acquisition and Interpretation Project. The Kombolgie survey area, in the Pine Creek Orogen of the Northern Territory, covered sections of the Cobourg Peninsula, Junction Bay, Alligator River, Milingimbi, Mount Evelyn, Katherine, and Urapunga 1:250 000 map sheets. It covered a total of 8 800 line km and an area of 32 000 km2. The data were acquired under contract by Geotech Airborne Pty. Ltd. using its VTEMTM helicopter-borne electromagnetic system. The inversions were carried out using the GA-LEI layered-earth inversion software developed at Geoscience Australia. Products include the layer conductivities, depth and elevation slices, and sections. The products are in digital form in both point-located and gridded formats. They are available for download from the Geoscience Australia website.
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A wide-angle reflection seismic survey coincident with a regional transect through Northeastern Yilgarn Craton focused on the Leonora-Laverton Tectonic Zone, Western Australia, was carried out to supplement deep seismic reflection studies. The major objectives were: to collect high-density refraction information for offsets of up to 60 km; to carry out a comparative study of near-vertical and wide-angle seismic images of the crust in the study area; to obtain velocity information for the upper crust. The survey deployed 120 short period recorders with a 500 m spacing. Acquisition parameters used for the wide-angle reflection experiment were selected so that it would to fit into the schedule and technology of the conventional reflection survey. The same vibrations were recorded in both surveys simultaneously. The major challenge in processing the wide-angle data was to manage the huge volume of information. The processing sequence included sorting into receiver and source gathers, cross-correlation with reference sweeps and stacking original seismic traces to form single source point traces, producing seismograms from individual traces and finally creating seismic record sections from separate seismograms. High amplitude seismic signal from vibroseis sources was recorded at least up to 50 km offsets in the first arrivals, and later arrivals were observed down to 12 s next to sources. A preliminary upper crustal model developed from the wide-angle data shows that the thickness of a high velocity layer, corresponding to the greenstone rocks, is 4.0-4.5 km. The boundary separating this layer from a low velocity layer below it is possibly a compositional boundary between greenstones and underlying felsic gneisses. There is no evidence for high velocity material below this boundary. Assuming the Moho belongs to deepest reflections modelled, total crustal thickness in the region can be speculatively estimated in the range 32-37 km.
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In 2008, the Ord Irrigation Cooperative commissioned an airborne electromagnetics (AEM) survey of the ORIA Stage 1 and 2 areas to identify, quantify and understand any potential salinity risks in the current Ord irrigation area and the parts of the catchment that have been identified as potential future irrigation sites or potentially impacted by future irrigation. The project has been funded by the Australian and Western Australian governments through the National Action Plan for Salinity and Water Quality. Geoscience Australia and CSIRO were contracted to carry out the analysis and interpretation of the AEM dataset, and produce customised interpretation products. Some of the more specific questions it was hoped to address included: - Are we at risk of salinity in the Ord Catchment? - If so what areas are at the greatest risk? - Where can we target management to reduce this risk? - How can we plan future development to minimise salinity risk and maximise longevity of projects? The areas surveyed include the current Stage 1 Ord Irrigation Area, Stage 2 Irrigation Area (including Weaber and Knox Plains and Carlton Hill - Parry's Lagoon Conservation Area. The inclusion of undeveloped land in this survey is because the technology provides the opportunity to ensure any future irrigation development is guided by the best available information on soil type, aquifer quality and location and salinity risk. The information generated by this project will be publicly available and can be used for such things as: - Identifying leaky areas in the landscape that may require more concentrated management or can be designated for more suitable land use; - Where salt is stored in the landscape and at what depth, and where in the landscape it may influence plant growth; - Provide new constraints on the connectivity of aquifer systems in 3D across the ORIA and enable the construction of more realistic hydrogeological models to improve surface and groundwater management.