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This progress report from South Australian Department of Mines and Energy, Water Resources Commission of New South Wales, Geological Survey of New South Wales, Rural Water Commission of Victoria, Department of Industry, technology and Resources Victoria, and Bureau of Mineral Resources. This project is a long-term study which is being under taken jointly by the bodies listed above. It is coordinated by a Steering Committee comprising members of those organisations. The primary aim of the Project is to improve the understanding of the groundwater regime of the Murray Darling basin by examining it as a single entity, unencumbered by State boundaries. Since a knowledge of the geology of an area is basic to the understanding of groundwater occurrence, a geological study of the basin is an essential part of the Project and, as a consequence, it will also be possible to make an assessment of other mineral resources.

Traditional aquifer tests are an expensive and time-consuming method for obtaining hydraulic information. Furthermore, in many environments, it is becoming increasingly difficult to obtain environmental clearances to dispose produced waters. In this study, the Nuclear Magnetic Resonance (NMR) method was evaluated to provide data on hydraulic conductivities (K) and transmissivities (T) of sediments within the Darling River Floodplain, Australia. NMR data were acquired every 0.5 m using a slim-hole logging system in 26 sonic cored wells to a depth of ~70 m. KNMR can be estimated from the NMR measurements using the Schlumberger-Doll Research Equation: KNMR = C x ?2 x T2ML2, where is the NMR effective porosity, T2ML is the logarithmic mean of the T2 distributions, and C is a formation factor related to tortuosity. Prior to the calculation of the KNMR, the NMR data were classified into five hydraulic classes ranging from clay to gravely-coarse sand using the core, geophysical, mineralogical, and hyperspectral logs. In selected zones aquifer tests were conducted to provide constraints on the K and T of the formations. Least-squares inversion was used to solve for the optimum C values for each of the hydraulic classes versus the aquifer test obtained T. Comparisons between laboratory permeameter measurements and KNMR indicated correspondence within two orders of magnitude. The borehole NMR method provides a rapid way of estimating the near continuous variations in K through a sedimentary sequence, while also providing useful estimates of K at a scale not achievable using traditional aquifer testing methods.

In recent years there has been a significant increase in the level of interest in Australia in hydrogeological maps. However, only a limited number of such maps have appeared as yet and there are currently no agreed guidelines for legends. It was for this reason that the Groundwater Committee of the Australian Water Resources Council established a Working Group to develop guidelines, bearing in mind recent developments in computer-assisted cartography. The authors of this report were members of that Working Group. A definitive set of guidelines has yet to be accepted by the Groundwater Committee. This report is produced as a contribution to the debate on hydrogeological maps and the depiction of data on such maps.

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The work presented is the outcome of a pilot program of 2 1/2 month's duration involving the preparation by Australian Groundwater Consultants (AGC) of a hydrogeological map of the Ballarat 1: 250 000 scale sheet, with accompanying explanatory notes. The pilot program was initiated by Bureau of Mineral Resources through funding provided by the Commonwealth Department of Resources and Energy,and was based on recommendations contained in a report to theDepartment by AGC on the National Groundwater Data Base Inventory 5 Year Forward Program. The pilot program report to BMR by AGC had three parts: volume 1 described the approach and methodology, the second part (volume 2) consisted of a copy of the Victorian Department of Industry, Technology and Resources (DITR) database used to compile the map, and the third part comprised the map and explanatory notes. In the present record the approach and methodology form part 1, and the explanatory notes and map part 2; only representative examples of the database files are included in part 1.

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 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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The groundwater modelling sub-committee set up by the Steering Committee in June 1980, met in October and recommended that a preliminary model of the Basin should be attempted; it should contain 3 layers, with a 10 x 10 grid (300 nodes) and have the aim of increasing theaccuracy of solutions at later stages by decreasing the grid size. The sub-committee proposed that a whole basin model be attempted by the South Australian Department of Mines & Energy using a finite element method, and by the Water Resources Commission of New South Wales using a finite difference approach; the methods could then be compared before a more elaborate model was tried.