Integrating surface water and groundwater sampling with pore fluid analysis of cored sediments, combined with fuzzy-k means (FCM) cluster analysis, provides a novel, relatively simple but powerful tool to interpret groundwater processes. This methodology has been applied to a study of shallow (<120m) alluvial aquifers in the Darling River floodplain, Pore fluids were extracted from sediments from 100 sonic-cored bores, and together with surface and groundwater samples, provided a hydrochemical dataset with over 1600 samples and 25 analytes. The FCM cluster analysis used analytes that were present in at least 60% of samples and resulted in samples being classified into eight classes (or hydrochemical facies). Pore fluids and groundwaters with the greatest affinity to the surface water samples were easily identified. In this way, sites with significant active recharge, principally by river leakage, were mapped. Downhole plots of the pore fluid FCM classes provided additional insights into groundwater processes. Comparing the FCM classification of pore fluids within the target (semi)confined aquifer with those from the overlying clay aquitard and shallow aquifer allowed the assessment of vertical inter-aquifer leakage. The FCM cluster analysis also assigns indices to each sample as indicators of how well it relates to each of the eight classes. A simple recharge index was calculated from these FCM indices. This novel approach has provided invaluable new insights into groundwater processes and has assisted greatly with assessing groundwater resources and managed aquifer recharge options.

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 Barr Creek - Gunbower 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 Groups 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.

One of the primary requirements of managing our water resources sustainably is an understanding of the water balance. Key components of a water balance model are inputs of recharge and outputs or discharge. Rates of recharge and discharge change in response to climate, landscape morphology, geology, soil/regolith, native vegetation and landuse (including landuse history). The variable nature of these parameters results in a high degree of local variability when determining recharge and discharge fluxes both spatially and temporally. Water managers deal with this complexity in a variety of ways. Where detailed information on key parameters influencing recharge and discharge are available, comprehensive, fully distributed groundwater models are used. However, in most cases this information is not available (e.g. data poor areas) and typically a crude estimation of recharge (2-10% of average annual rainfall) is given. In these cases, discharge is often assumed to be zero. A collaborative project, funded by NWC and involving CSIRO Land and Water and Geoscience Australia, has developed a new national framework for estimating recharge and discharge in data poor areas. The approach consists of excel-based models that allow the user to populate key input fields (e.g. rainfall, soil and regolith texture, bedrock type, vegetation) to generate estimates of recharge and discharge. These excel models have been coupled with a complementary national-scale GIS dataset to assist the user in populating model input fields. In combination, the models and the GIS datasets allow the user to rapidly estimate recharge and/or discharge anywhere in Australia. The national-scale GIS datasets are available through a WEB-based interface. This presentation will focus on the development of the input datasets and will provide a brief demonstration of the WEB-based interface.

Legacy product - no abstract available

Submission to the Parliamentary Joint Committee on the Australian Capital Territory concerning the inquiry into long-term collection and disposal techniques for Canberra city waste. In Canberra, solid waste is disposed of in open dumps and sanitary landfill sites. A major environmental problem resulting from such practice is the pollution of groundwater by leachate, and the monitoring of groundwater pollution is an essential part of landfill management that must be continued long after a site is closed. The selection of landfill sites depends on the physical constraints of geology and hydrogeology, but planners do not always sufficiently consider the physical constraints in the selection of landfill sites. The success of a landfill site depends mainly on site selection,and must be supported by good site management techniques and groundwater-pollution monitoring procedures. In many communities, public authorities maintain good land-fill practice by setting high standards for landfill operators, and by controlling the site through regulations and the supervision of monitoring procedures.

The use of airborne electromagnetics (AEM) for hydrogeological investigations often requires high resolution data. Optimisation of AEM data therefore requires careful consideration of AEM system suitability, calibration, validation and inversion methods. In the Broken Hill managed Aquifer Recharge (BHMAR) project, the helicopter-borne SkyTEM transient EM system was selected after forward modeling of system responses and assessment of test line data over potential targets. The survey involved acquisition of 31,834 line km of data over an area of 7,500 km2 of the River Darling Floodplain, and was acquired by two systems over a 9-week period.. Initial Fast Approximate Inversions (FAI) provided within 48 hours of acquisition were used to target 100 sonic and rotary mud holes for calibration and validation. A number of different (Laterally and Spatially Constrained) inversions of the AEM data were carried out, with refinements made as additional information on vertical and lateral constraints became available. Finally, a Wave Number Domain Approximate Inversion procedure with a 1D multi-layer model and constraints in 3D, was used to produce a 3D conductivity model. This inversion procedure only takes days to run, enabling the rapid trialing to select the most appropriate vertical and horizontal constraints. Comparison of borehole induction logs with adjacent AEM fiduciary points confirms high confidence levels in the final inversion. Using this approach has produced quantitative estimates of the 3D conductivity structure that provide a reliable platform for identifying new groundwater resources and a range of MAR options, and developing new geological and hydrogeological conceptual models. Integration of the AEM data with borehole lithology, textural, mineralogical, groundwater and pore fluid hydrochemical and borehole NMR data has enabled maps of hydrostratigraphy, hydraulic conductivity, groundwater salinity, salt store and neotectonics to be produced.

This Geocat record is a CD of presentations delivered as part of the 4th Technical Advisory Group workshop for the Palaeovalley Groundwater Project. The workshop was held in Canberra at Geoscience Australia on 5 and 6 April 2011 and involved ~20 people including GA staff and invited guests from state government water resource and geological survey organisations in SA, NT and WA. The CD has been compiled as a record of the workshop and will be delivered to the workshop participants as a record of the event.

Technical report on operational activities, including data, analysis and interpretation, for the Paterson demonstration study site conducted for the Palaeovalley Groundwater Project. This work was funded by the National Water Commission and managed by Geoscience Australia.

Salt lakes, also known as playa lakes, are a common feature of the Australian landscape, and are a strong indicator of our current and past climates. Despite their abundance they have not been extensively studied in Australia, with little research undertaken since the early benchmark work of the 1970s - 1980s (e.g. Bowler, 1971, 1981) which largely focussed on geomorphologic evolutionary patterns and trends. Notwithstanding, salt lakes contain some of the highest levels biological endemism in Australia (DeDecker, 1983) and their unique, and commonly extreme, chemistry offers the potential for distinctive saline mineralisation and potentially economic concentrations of Li, K, B, REEs, Br and U (e.g. Butt et al. 1984; Nissenbaum, 1993; Orris, 2011).

The Murray River is known to display great complexity in surface-groundwater interactions along its course, with 'gaining' sections of the river identified as sites of regional saline groundwater system discharges to the river and the adjacent floodplain. In the Lindsay - Walpolla reach of the River Murray, an airborne electromagnetics (AEM) survey acquired in a 20 km 'wide swath along the river, has enabled key elements of the hydrogeological system to be mapped. Electrical geophysical methods (such as AEM) are able to map the extent and thickness of lateral bank infiltration ('flush') zones, due to the contrast between fresh water leaking from the river and brackish to saline groundwater in adjacent sediments. This study found flush zones in the study area to be present relatively continuously to depths of 5-10m in zones of varying width (200m to <4 km). Development of flush zones to greater depths (up to 25 m) is restricted. The River is interpreted as a weakly losing reach of the river system (at the time of the AEM survey). The most extensive flush zones in the study area are associated with locks, weirs and irrigation districts. Salt mobilisation associated with the flush zones at weir pools may be an issue in terms of salt load delivery to the River Murray and floodplain. Reaches of the river where the flush zones are absent and /or significantly constricted, and similar zones in tributary creeks in the adjacent floodplain, are at higher risk of saline groundwater inflows.