This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and is presented here as originally supplied.
The GAB hydrogeological boundary follows the geological margins of its four component sub-basins - the Eromanga, Carpentaria, Surat and Clarence-Moreton sub-basins - except where the water table indicates groundwater divides within these regions that delineate externally-draining regions. In some regions, this drainage divide changes geographically through the GAB sequence. In such areas as the GAB boundary within the Clarence-Moreton Basin, the broadest hydrogeological extent has been adopted as the GAB boundary. This dataset documents a basin-wide hydrostratigraphy of the GAB comprising five major aquifers, four intervening aquitards, and the cover of these units by Cenozoic rocks and sediments. The extensive Quaternary sediment cover is considered permeable and not an impediment to the recharge of underlying aquifers. However, the underlying Paleogene-Neogene rocks and sediments have highly variable hydrogeological character that can influence deeper connectivity. In this map individual aquifers and aquitards within the Paleogene-Neogene sequence have not been differentiated. There are two data layers in the Great Artesian Basin - Hydrogeology map data A: Hydrogeological unit boundaries B: GAB Boundary This is a regional interpretation for mapping at approximately 1:1 000 000 to produce a broad scale overview, and examination of small areas by collecting extra data is most likely to produce results that differ from this regional interpretation. This dataset and associated metadata can be obtained from www.ga.gov.au, using catalogue number 81672. REFERENCES: Ransley, T., Radke, B., Feitz, A., Kellett, J., Owens, R., Bell, J. and Stewart, G., 2015. Hydrogeological Atlas the Great Artesian Basin. Geoscience Australia. Canberra. [available from www.ga.gov.au using catalogue number 79790] Habermehl, M. A. and J. E. Lau (1997). Hydrogeology of the Great Artesian Basin Australia (Map at scale 1:2,500,000). Canberra, Australian Geological Survey Organisation.
METHOD: Formation Extent Extent lines were adjusted from the Hydrogeology of the Great Artesian Basin Australia dataset (Habermehl & Lau, 1997) using geology datasets (see data sources) to envelop all intercepts of the Hydrostratigraphic unit. This produced some varied and irregular shapes, some patchy regions, and required some interpretation to establish the most likely extent boundary. QAQC: Data has undergone a QAQC verification process in order to capture and repair attribute and geometric errors. SOFTWARE: All modifications/edits and geoprocessing were performed using ESRI ArcGIS 10 software.
Geoscience Australia (2015) Great Artesian Basin - Hydrogeology and Extent Boundary. Bioregional Assessment Source Dataset. Viewed 25 October 2017, http://data.bioregionalassessments.gov.au/dataset/020957ea-4877-4009-872c-3cacfb6f8ded.