In many floodplain landscapes in Australia, surface-groundwater interactions are poorly understood. 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 a detailed 3-Dimensional map of surface geomorphology and hydrogeology. These maps enable 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 continuity of (and presence of) 'holes' in near-surface and deeper aquitard layers derived from the AEM. 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/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 an assessment of managed recharge options and locations.

Under Geoscience Australia's Onshore Energy Security Program (OESP), Airborne Electromagnetic (AEM) data were acquired in areas considered prospective for unconformity-related and palaeochannel-hosted uranium deposits. The program was aimed at reducing exploration risk and promoting exploration activity. The surveys were designed to reveal new information about regions by acquiring the AEM data at line spacings of one to six kilometres over relatively large areas. As well as enhancing the search for uranium and other energy sources, the survey results will be relevant in exploration for a variety of commodities and other resources, including groundwater. This data release contains the flight-paths and survey boundaries for the three AEM surveys conducted under the OESP: 1. Paterson Province (Western Australia) 2. Pine Creek (Northern Territory) 3. Frome Embayment (South Australia)

During 2008 and 2009, and under the Australian Government's Onshore Energy Security Initiative, Geoscience Australia acquired airborne electromagnetic (AEM) data over the Pine Creek Orogen of the Northern Territory. The survey area was split into three areas for acquisition. VTEM data was acquired in the Kombolgie area east of Kakadu National Park between August and November 2008. TEMPEST data was acquired west of Kakadu National Park with the area split in two to facilitate the use of two aircraft: the Woolner Granite area in the north was acquired between October and December 2008; and the Rum Jungle area (this data set) adjoining to the south, which was acquired between October 2008 and May 2009. The main purpose of the surveys was to provide additional geophysical/geological context for unconformity style uranium mineral systems and thereby promote related exploration. The survey data will also provide information on depth to Proterozoic/Archean basement, which is of general interest to explorers, and will be used as an input into ground water studues in the region.

A PowerPoint presentation showing regional interpretations of data from the Frome airborne electromagnetic survey, presented at a workshop on 30 November 2011 at the University of Adelaide, South Australia

Borehole induction conductivity data, commonly referred to as conductivity logs, were acquired from 20 boreholes in the Frome region of South Australia, during July-August 2010, in support of the Frome airborne electromagnetic (AEM) survey managed by Geoscience Australia (GA). The conductivity logs were used to assist in generating reference models for geophysical inversions of the AEM data, and to provide an independent dataset for assessing the inversion results. The Frome AEM survey was acquired using the Fugro Airborne Surveys (FAS) TEMPEST fixed wing time-domain electromagnetic (TEM) AEM system. The acquisition and processing of data were carried out by FAS under contract to GA. The geophysical investigations were designed to deliver reliable, pre-competitive AEM data and scientific analysis of the energy resource potential of the Frome region of South Australia, including the flanks of the Northern Flinders Ranges, the Frome Embayment, the Olary Ranges and the northwestern Murray Basin. The Frome AEM survey covers a total area of 95,000 km2 and was flown between 22 May and 2 November 2010.

Data from a VTEM airborne electromagnetic survey over resistive terrain is examined. Forward modelling and analysis of high-altitude lines shows that the amplitudes of random noise, bucking error, processing corrections and geological signals can be large compared to the geological signal in the resistive terrain. The negative impacts of the low geological signal to noise ratio on conductivity estimates generated by layered-earth inversion and conductivity transformations are demonstrated. The reader is alerted to the degree of uncertainty and non-uniqueness that is inherent in conductivity estimates generated from similar datasets.

The continuing world demand for potash (potassium salts) is driving a new exploration boom in the Australian minerals industry for this valuable resource, listed by Geoscience Australia (GA) as a strategic commodity (Mernagh 2013). The Food and Agriculture Organization of the United Nations (FAO) predicts a rising demand for fertilizers, with potash demand increasing at 3.7% per annum (FAO 2012), and Rabobank predicts that demand will exceed supply by up to 100% by 2020 (Rabobank 2012). This demand is driving the application of airborne electromagnetics (AEM) to map salinity as a proxy for potential potash resources in salt lakes. This short paper describes a few of the applications and is written in response to an industry request to GA for information on how AEM might be used to explore for potash.

The record is a presentation given by Adrian Fisher to staff of the Aditya-Birla Nifty copper mine and to staff at the Geological Survey of Western Australia, August 2007. It describes the planning behind the Paterson AEM survey, to be acquired in 2007-2008.

The holistic inversion approach for frequency domain AEM data (Brodie and Sambridge, 2006) has previously been employed to simultaneously calibrate, process and invert raw frequency-domain data where prior information was available. An alternative formulation has been developed, which is suitable in the case where explicit prior information is not available. It incorporates: a multi-layer vertically-smooth conductivity model; a simplified bias parameterization; horizontal smoothing with respect to elevation; and cluster computer parallelisation. Without using any prior data, an inversion of 8.0 million data for 3.4 million parameters yields results that are consistent with independently derived calibration parameters, downhole logs and groundwater elevation data. We conclude that the success of the holistic inversion method is not dependent on a sophisticated conceptual model or the direct inclusion of surrey-area specific prior information. In addition, acquisition costs could potentially be reduced by employing the holistic approach which may eliminate the need for high altitude zero-level measurements.

Geoscience Australia contracted an airborne electromagnetic (AEM) survey over the Frome Embayment, South Australia, under the Australian Government's Onshore Energy Security Program. The Frome AEM survey was acquired using the Fugro Airborne Surveys (FAS) TEMPEST fixed wing time-domain electromagnetic (TEM) AEM system. The acquisition and processing of data were carried out by FAS under contract to Geoscience Australia. The Frome AEM survey consists of 32 300 line km, covering a total area of 95 000 km2 and was flown between 19 May and 2 November 2010. The survey was designed to deliver reliable, pre-competitive AEM data and scientific analysis of the energy resource potential of the Frome region of South Australia, including the flanks of the Northern Flinders Ranges, the Frome Embayment, the Olary Ranges and the northwestern Murray Basin. The survey data may also be used as an input to groundwater studies in the region. This presentation was given at a Frome AEM Workshop in Adelaide - November 2011.