Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile–Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

Chongo, Mkhuzo; Christiansen, Anders Vest; Fiandaca, Gianluca; Nyambe, Imasiku; Larsen, Flemming; Bauer‐Gottwein, Peter

doi:10.1016/j.jappgeo.2015.10.002

Cited by 13 publications

(12 citation statements)

References 54 publications

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“…The elevation of the survey area sharply changes at Geophysical method especially Transient Electromagnetic (TEM) technique, as being non-invasive and cost-effective, acquisition of strong signals, deep levels of penetration, easy deployment, and suitability for geological exploration, which remains the first choice to explore the target with conductive characters. TEM has been widely used in various fields, such as engineering geology [20] and environmental geophysics investigations [21], mining [22], urban construction [23], tunnel prediction, and groundwater [24] and geothermal explorations. Due to its sensitivity to conductive geologic body when compared to the surrounding rocks with high resistivity, TEM has received great attention in the mined-out area with water investigations [25].…”

Section: Geologic Settingmentioning

confidence: 99%

Application of Transient Electromagnetic Method for Investigating the Water-Enriched Mined-Out Area

Liu

et al. 2018

Applied Sciences

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The water-enriched mined-out area, which led to frequent accidents and the serious destruction of ecological environment and serious threat to coal-mining practices. To ensure safe mining practices and to avoid the intrusion of water from the bases of coal deposits, the detection of the mined-out areas, especially the water-filled mined-out area in advanced, is one of the most important issues. This research focuses on detecting mined-out area enriched by water with the large-loop transient electromagnetic method. Data acquisition system was arranged along 23 survey lines, and the total of 1975 survey points were recorded. An inversion technique was used to interpret the TEM data. The inversion results suggested that the mined-out areas enriched by water always exhibit a very low-resistivity, the resistivity contour present closed circle sharp. There are three main water enriched mined-out areas, named JS1, JS2, and JS3 in the north part of the survey area, as well as three main water weak-enriched areas named RJS1, RJS2 and RJS3 in the west and southwest part of the survey area can be inferred by TEM, the interpretation results were verified by drilling. Large loop TEM is proved as an efficient way to investigate water enriched mined-out areas under the rugged topography conditions, and this work provides more detailed geological information to the coal mining enterprise for further coal-mining practices safety arrangement.

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Section: Geologic Settingmentioning

confidence: 99%

Application of Transient Electromagnetic Method for Investigating the Water-Enriched Mined-Out Area

Liu

et al. 2018

Applied Sciences

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“…The current view is that TFLs are quite rare [Houben et al, 2014]. However, recent discoveries of new TFLs in Paraguay [Houben et al, 2014], Australia and Zambia [Chongo et al, 2015] indicate that TFLs may be more widespread than previously thought. No previous attempt to review their occurrence, origins and controlling factors has been made.…”

Section: Introductionmentioning

confidence: 92%

“…Lens contraction occurs during dryer periods as the surface water levels fall and the hydraulic gradients reduce and/or reverse. Australia's Murray River and the Zambezi River in Zambia produce lenses of this type [Cartwright et al, 2010[Cartwright et al, , 2011Chongo et al, 2015]. The Murray River TFL, located in the Colignan-Nyah region of Victoria, was characterized primarily from geochemical analyses [Cartwright et al, 2010], whereas "low resistivity anomalies" in a geophysical survey lead to the discovery of the TFL on the Zambezi River [Chongo et al, 2015].…”

Section: Known Terrestrial Freshwater Lensesmentioning

confidence: 99%

“…The host aquifer geology is shown to influence both the TFL and the regional saline groundwater [Bauer et al, 2006]. The significance of flood inundation recharge for both continuously losing and continuously gaining river lenses is unresolved in some situations [Chongo et al, 2015;, and requires further investigation. Further information about each identified TFL is provided in a table as supplementary material with the electronic version of this document.…”

Section: Known Terrestrial Freshwater Lensesmentioning

confidence: 99%

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Terrestrial freshwater lenses: Unexplored subterranean oases

Laattoe

Werner

Woods

et al. 2017

Journal of Hydrology

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Freshwater lenses are lenticular bodies of fresh groundwater that develop above more saline groundwater within the same host aquifer due in part to buoyancy. In contrast to the widely studied situation of freshwater lenses in coastal aquifers, the formation, location and persistence of freshwater lenses in terrestrial settings are poorly understood. This is despite inland aquifers commonly containing saline groundwater, particularly in arid and semi-arid climates, and the local occurrences of freshwater being critical for ecosystems and human endeavour. We identify and classify known terrestrial freshwater lenses (TFLs) using four formation categories, namely topography, geology, groundwater-surface water interaction and recharge mechanisms. The resulting typology highlights the importance of buoyancy in the formation of TFLs in otherwise unlikely situations, implying that TFLs may be more prevalent than previously thought. TFLs represent some of the most vulnerable and precious freshwater resources on Earth that require considerably more research into mechanisms of formation and threats to their existence.

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“…Several examples of spectral TDIP applications for different purposes have been presented (Gazoty et al 2012a(Gazoty et al , 2013bChongo et al 2015;Fiandaca et al 2015;Johansson et al 2015;Doetsch et al 2015a,b). Furthermore, efforts have been made to achieve faster acquisitions and a better signal-to-noise ratio (SNR) by using a 100 per cent duty cycle current waveform, without current off-time (Olsson et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Doubling the spectrum of time-domain induced polarization by harmonic de-noising, drift correction, spike removal, tapered gating and data uncertainty estimation

Olsson¹,

Fiandaca

Larsen

et al. 2016

Geophys. J. Int.

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Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile–Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

Cited by 13 publications

References 54 publications

Application of Transient Electromagnetic Method for Investigating the Water-Enriched Mined-Out Area

Application of Transient Electromagnetic Method for Investigating the Water-Enriched Mined-Out Area

Terrestrial freshwater lenses: Unexplored subterranean oases

Doubling the spectrum of time-domain induced polarization by harmonic de-noising, drift correction, spike removal, tapered gating and data uncertainty estimation

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