Nauru, in the central Pacific Ocean, is a raised atoll capping a volcanic seamount arising from an ocean floor depth of 4300m. The land area is 22km, and the island rises to 70m above sea level. Drilling has proved dolomitised limestone of upper Miocene or younger age to a depth of 55m below sea level. Gravity and magnetic surveys indicate that the limestone probably overlies volcanic bedrock at a depth of about 500m. Reverse-circulation drilling and geoelectrical probes indicate that there is a discontinuous freshwater layer averaging 5m thick beneath Nauru. This is underlain by a mixing zone of brackish water, 60-70m thick. The exceptional thickness of the mixing zone is ascribed to high permeability of the karstified limestone. The forthcoming cessation of phosphate mining will mean a shortfall in water supply which will probably have to be met by the desalination of brackish water. Groundwater beneath the mined-out area, and the settled coastal terrace, is highly vulnerable to pollution, and waste disposal management needs to be considered in relation to groundwater protection.

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.

Legacy product - no abstract available

The GIS supports Professional Opinion 2009/03 Geocat #68672 A detailed analysis of aquifer systems in the Broken Hill Managed Aquifer Recharge priority areas has clarified our understanding of key components of the aquifer systems. Of the priority areas examined in detail, the aquifers located in the Darling Floodplain are considered to have the greatest potential for developing Managed Aquifer Recharge (MAR) options and for hosting significant volumes of previously undefined fresh and brackish groundwaters with low levels of allocation, thereby assisting the larger strategic effort aimed at identifying significant water-saving measures for the Darling River system.

Legacy product - no abstract available

<p>Appendices (see Record for details): <p>1 - Graphical display of borehole geological and geophysical logs and hydrogeochemical data <p>2 - Core photography <p>3 - Borehole geophysical and geological data <p>4 - AEM data acquisition, inversion, calibration and basic conductivity map and cross-section products <p>5 - AEM-based interpretation products: maps and cross-sections <p>6 - Hydrological, climate, hydrochemical and hydrodynamic data <p>7 - Age dating contractor reports <p>8 - Recharge models and data <p>9 - Remote sensing /vegetation health analysis background data and intermediate products <p>10 - Ground and in-river geophysics and supporting data <p>11 - CSIRO MAR reports <p>12 - Drilling construction, location and remediation data and reports <p>13 - Borehole Hydraulic Data (contractor reports) <p>14 - LIDAR acquisition and processing contractor reports <p>15 - Cultural Heritage and clearances <p>Prepared for: The Australian Government Department of Sustainability, Environment, Water, Population and Communities (DSEWPaC)

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.

The Steering Committee met on 3rd June in Canberra, and one of the matters agreed upon was that a field inspection of parts of the Basin should be held for geologists and hydrogeologists working on the Project, mainly to discuss stratigraphic correlation problems and, as well, hydrogeological aspects. Detailed planning for the field inspection, scheduled to begin early in October, and preceded by a one-day seminar, was completed. Work on a preliminary groundwater model of the whole Basin at the Geological Survey of Victoria has resulted in the development of a model to the operational stage. At BMR the compilation of available geological and geophysical data has continued steadily, and by the end of the year it is expected that all bores from which stratigraphic information has been obtained will have been plotted, and preparation of structure contour maps can begin.

Work continued on the compilation of the geological map of the Basin and associated figures. The Steering Committee met in December during the International Conference "Groundwater and Man" at the University of New South Wales, and one outcome of the meeting was the provision of a statement on the current status of the Project to the Victorian Parliamentary Salinity Committee, the Interim Council of the Institute of Freshwater Studies, and the River Murray Commission. During the period Dr R.S. Evans was nominated to represent the Victorian State Rivers and Water Supply Commission on the Steering Committee.

How much easier it would be to map and quantify the key elements of the hydrological cycle if the Earth's surface was transparent! Unfortunately, this is not the case and it is this very inability to penetrate to sufficient depths to map and quantify groundwater components of the hydrological cycle that currently necessitates the integration of satellite- airborne- and ground observations. In Australia, important advances have been made in the last 3 years in quantifying key elements of the hydrological cycle. This has been achieved in part through the increased use of Landsat, MODIS, SPOT, hyperspectral, NOAA and LiDAR datasets to improve the mapping and quantification of surface water, evapotranspiration, soil moisture and recharge and discharge. However, significant limitations remain in using satellite-based platforms alone for quantifying catchment water balances, surface-groundwater interactions, groundwater resource estimation and managing groundwater dependent ecosystems. Increasingly, the need to map the key elements of the hydrological cycle to calibrate water balance models and for environmental management, is leading to the development of more holistic systems approaches, involving the integration of satellite-, airborne and ground-based techniques and measurements. One example is in the River Murray Corridor (RMC) in SE Australia, where previous attempts to assess the water needs for iconic floodplain wetland ecosystems, based largely on satellite-based measurements, did not adequately take into account sub-surface soil conditions and groundwater quality and processes. In floodplain environments such as the River Murray Floodplain, the factors that govern tree health are invariably complex, and include a wide range of biophysical and biogeochemical factors.