Authors / CoAuthors
Lawrie, K. | Brodie, R.C. | Brodie, R.S. | Tan, K.P. | Christensen, N.B. | Abraham, J.
Abstract
The use of airborne electromagnetics (AEM) for hydrogeological investigations often requires high resolution data. Optimisation of AEM data therefore requires careful consideration of AEM system suitability, calibration, validation and inversion methods. In the Broken Hill managed Aquifer Recharge (BHMAR) project, the helicopter-borne SkyTEM transient EM system was selected after forward modeling of system responses and assessment of test line data over potential targets. The survey involved acquisition of 31,834 line km of data over an area of 7,500 km2 of the River Darling Floodplain, and was acquired by two systems over a 9-week period.. Initial Fast Approximate Inversions (FAI) provided within 48 hours of acquisition were used to target 100 sonic and rotary mud holes for calibration and validation. A number of different (Laterally and Spatially Constrained) inversions of the AEM data were carried out, with refinements made as additional information on vertical and lateral constraints became available. Finally, a Wave Number Domain Approximate Inversion procedure with a 1D multi-layer model and constraints in 3D, was used to produce a 3D conductivity model. This inversion procedure only takes days to run, enabling the rapid trialing to select the most appropriate vertical and horizontal constraints. Comparison of borehole induction logs with adjacent AEM fiduciary points confirms high confidence levels in the final inversion. Using this approach has produced quantitative estimates of the 3D conductivity structure that provide a reliable platform for identifying new groundwater resources and a range of MAR options, and developing new geological and hydrogeological conceptual models. Integration of the AEM data with borehole lithology, textural, mineralogical, groundwater and pore fluid hydrochemical and borehole NMR data has enabled maps of hydrostratigraphy, hydraulic conductivity, groundwater salinity, salt store and neotectonics to be produced.
Product Type
nonGeographicDataset
eCat Id
73804
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
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2601
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Keywords
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- External PublicationAbstract
- ( Theme )
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- AEM
- ( Theme )
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- hydrogeology
- ( Theme )
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- groundwater
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2012-03-15T00:00:00
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