Authors / CoAuthors
Kellet, J.
Abstract
Watertable contours were constructed from recent water level data in the state databases of NSW and Queensland. SA and NT data points were from Flinders University. SA water levels were corrected for density effects due to salinity. Elsewhere, density corrections for the watertable aquifer are not deemed to be an issue. Similar to the confined aquifers, regional groundwater flow in the watertable aquifers is from the highest potentials in the intake beds on the western slopes of the Great Dividing Range (GDR) in New South Wales and Queensland. This intake zone extends northward along the western slopes of the GDR to the tip of Cape York where the pressures are lower than those in the southern recharge area. The watertable lies in the Jurassic formations in the intake beds but basinward it passes into the Early Cretaceous formations (Winton (Kw) and Mackunda (Klm) Formations in the Eromanga Basin, Griman Creek Formation in the Surat Basin). These aquifers comprise the most areally extensive host for the watertable in the GAB. In the Lake Eyre and Karumba Basins, the watertable passes into Cenozoic sediments. Regional discharge zones for the watertable are Lake Eyre and an eastward arcuate band of salt lakes extending from Lake Frome to Lake Gregory. Both of these regional discharge zones lie in SA but there is another intra-basin discharge area at the Bulloo Overflow/Caryapundy Swamp on the NSW/Queensland border. Regional discharge from the watertable in the Carpentaria/Karumba Basins is the Gulf of Carpentaria. Regional discharge from the Coonamble Embayment watertable is the Darling River alluvium. There are subtle features evident in the watertable map which distinguish it from the potentiometric surface map of the Hooray Sandstone (JKh) confined aquifer. - The watertable contours are not smooth like the JKh contours, but form local recharge mounds extending far into the basin. Some of these recharge mounds are coincident with structures like the Innamincka Dome and all of them occur in areas mapped as Kw or Klm outcrop, or in areas where the Lower Cretaceous rocks are shallowly buried by Cenozoic sediments. In the Eromanga Basin, the total intra-basin recharge into the Kw and Klm aquifers is estimated to be 164 GL/year which is 21 GL/year higher than recharge to the Hooray and Hutton Sandstones on the western slopes of the GDR. Intra-basin recharge has never before been included in GAB water budgets. - The two largest rivers in the Eromanga Basin, the Diamantina River and the Cooper Creek are prominent watertable drains. By way of contrast, there is no apparent relationship between these major streams and the JKh potentiometry. - The watertable mounds along the Eulo Ridge and their extension south-westwards toward the Yancannia Range in NSW come close to forming a groundwater divide between the Surat and Eromanga Basins, but the line of mounds is breached in some places permitting impeded lateral throughflow. For the watertable, the Eulo Ridge acts as is an impermeable subsurface boundary but there is no apparent influence of this structure or its hydrogeological role on the JKh potentiometry.
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nonGeographicDataset
eCat Id
75707
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
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- External Publication
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2013-01-01T00:00:00
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