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.

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.

Legacy product - no abstract available

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.

Legacy product - no abstract available

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.

Tarawa is a coral atoll in the Gilbert Islands; it consists of a number of low islands, several of which contain discrete freshwater lenses overlying salt water. Resistivity depth probes indicate that the largest untapped lens is on the northern island of Buariki, and that this lens is up to 29m thick. The total safe yield of the Tarawa freshwater lenses is probably more than 12 1/s,and there is scope for the present groundwater development system of infiltration galleries to be extended.

This is the third quarterly report on the progress of the Murray Basin Hydrogeological Project. Participating organisations are the Geological Survey of New South Wales, the Water Resources Commission of New South Wales, the Geological Survey of Victoria, the State Rivers and Water Supply Commission of Victoria, the Department of Mines and Energy of South Australia, and the Bureau of Mineral Resources.

Legacy product - no abstract available

This is the second quarterly report on the progress of the Murray Basin Hydrogeological Project. In this report an outline map of the basin is included to indicate where activities have occurred during the quarter, and the general statement describing the Project forms the appendix. Participating organisations are the Geological Survey of New South Wales, the Water Resources Commission of New South Wales, the Geological Survey of Victoria, the State Rivers and Water Supply Commission of Victoria, the Department of Mines and Energy of South Australia, and the Bureau of Mineral Resources.