Authors / CoAuthors
Tan, K.P. | Lawrie, K.C. | Clarke, J.D.A. | Halas, L. | Fell-Smith, S. | Sumner, J. | Apps, H.E.
Abstract
Seawater intrusion (SWI) is a problem globally due to changes in catchment water balances and rising sea levels. The northern coastline of Australia is an area of incipient SWI hazard; however, there is limited understanding of the characteristics of SWI. This study undertook a regional TEMPEST AEM survey of the Darwin coastal plains over the Koolpinyah Dolostone (KD) aquifer, to inform understanding of SWI in this important urban and peri-urban water source. Calibration and validation of AEM data involved sonic and rotary mud drilling, borehole geophysical and geological logging, and laboratory analysis of lithologies, pore fluids and groundwater samples. The AEM data provide greater spatial detail of critical elements of the hydrostratigraphy, and map a complex SWI interface in 3D. A potential SWI hazard to the main producing aquifer has been identified, with SWI ingress through preferential flow paths mapped along structural corridors. There is also extensive leakage of saline groundwater beneath the tidal Adelaide and Mary River floodplains. The existing regional hydrogeological model requires major revision to incorporate the significant weathered zones and salt stores, more restricted extent of dolostone in the aquifer,, and preferential recharge zones and groundwater flow paths to the KD aquifer identified through this study. Assessment of SWI risk to the groundwater resource requires additional hydrodynamic data targeted using the AEM data, and incorporation of results within a predictive groundwater model. The study demonstrates the value of regional, AEM surveys in understanding SWI proceses in karstic aquifers, particularly in data-poor, inaccessible or environmentally sensitive areas.
Product Type
nonGeographicDataset
eCat Id
73649
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Custodian
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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2601
Australia
Keywords
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- GA PublicationAbstract
- ( Theme )
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- hydrogeology
- ( Theme )
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- groundwater
- ( Theme )
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- marine
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2012-01-01T00:00:00
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geoscientificInformation
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[-12.818008, -12.141118, 130.985183, 131.773448]
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