Groundwater Exploration With Aem in the Boteti Area, Botswana

Sattel, Daniel; Kgotlhang, Lesego

doi:10.1071/eg04147

Cited by 24 publications

(13 citation statements)

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“…Given the relationship between electrical resistivity and the properties of the subsurface geological materials, AEM data can be used, along with existing lithologic information available from drillers' logs, to develop a model of the large‐scale (tens to hundreds of meters) hydrostratigraphic packages that define the architecture of the aquifer systems. The AEM method has been used throughout the world for groundwater exploration and aquifer mapping (e.g., Sattel and Kgotlhang ; Podgorski et al ). The various methods that have been used to develop the hydrostratigraphic model are described in a recent paper by Christensen et al () and include both knowledge‐driven cognitive approaches (e.g., Jørgensen et al ) and geostatistical approaches (e.g., Marker et al ).…”

Section: Introductionmentioning

confidence: 99%

Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California

Knight¹,

Smith

Asch³

et al. 2018

Groundwater

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The passage of the Sustainable Groundwater Management Act in California has highlighted a need for cost-effective ways to acquire the data used in building conceptual models of the aquifer systems in the Central Valley of California. One approach would be the regional implementation of the airborne electromagnetic (AEM) method. We acquired 104 line-kilometers of data in the Tulare Irrigation District, in the Central Valley, to determine the depth of investigation (DOI) of the AEM method, given the abundance of electrically conductive clays, and to assess the usefulness of the method for mapping the hydrostratigraphy. The data were high quality providing, through inversion of the data, models displaying the variation in electrical resistivity to a depth of approximately 500 m. In order to transform the resistivity models to interpreted sections displaying lithology, we established the relationship between resistivity and lithology using collocated lithology logs (from drillers' logs) and AEM data. We modeled the AEM response and employed a bootstrapping approach to solve for the range of values in the resistivity model corresponding to sand and gravel, mixed coarse and fine, and clay in the unsaturated and saturated regions. The comparison between the resulting interpretation and an existing cross section demonstrates that AEM can be an effective method for mapping the large-scale hydrostratigraphy of aquifer systems in the Central Valley. The methods employed and developed in this study have widespread application in the use of the AEM method for groundwater management in similar geologic settings.

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Section: Introductionmentioning

confidence: 99%

Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California

Knight¹,

Smith

Asch³

et al. 2018

Groundwater

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“…The TEM data were used by Campbell et al (2006) to set the lateral extent of potential freshwater aquifers as well as the fresh-saline water interface. Earlier work by Sattel and Kgotlhang (2004) (Moore et al 2012).…”

Section: Introductionmentioning

confidence: 98%

Airborne and ground‐based transient electromagnetic mapping of groundwater salinity in the Machile–Zambezi Basin, southwestern Zambia

Chongo

Christiansen

Tembo

et al. 2015

Near Surface Geophysics

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21The geological and morphological evolution of the Kalahari Basin of Southern Africa has 22 given rise to a complex hydrogeological regime that is affected by water quality issues. 23Among these concerns is the occurrence of saline groundwater. Airborne and ground-based 24 electromagnetic surveying is an efficient tool for mapping groundwater quality variations and 25 has been used extensively to explore the Kalahari sediments, e.g., in Botswana and Namibia. 26 Recently, airborne-and ground-based mapping of groundwater salinity was conducted in the 27 Machile-Zambezi Basin, southwestern Zambia, using the versatile time-domain 28 electromagnetic system and WalkTEM system, respectively, incorporating earlier ground-29 based ProTEM 47D measurements. The data were inverted using the laterally constrained

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“…Electrical and electromagnetic methods offer efficient means for studying the hydrogeology and lithologies of the Okavango Delta (MMEWR, 2004;Sattel and Kgotlhang, 2004;Bauer et al, 2006;Shemang and Molwalefhe, 2009;Bauer-Gottwein et al, 2010). Because electrical resistivity is generally a good proxy for water saturation, salinity, and lithology, these methods have long been used for investigating aquifer systems worldwide (e.g., Fitterman and Stewart, 1986;Albouy et al, 2001;Danielsen et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Hydrogeophysical investigations in the western and north-central Okavango Delta (Botswana) based on helicopter and ground-based transient electromagnetic data and electrical resistance tomography

et al. 2014

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The Okavango Delta is a huge alluvial megafan in northwestern Botswana. Despite numerous geologic, geochemical, geophysical, and hydrologic investigations over the past half-century, the sedimentary units underlying the delta are largely unknown. To address this issue, helicopter transient electromagnetic data (HTEM) have been collected across the entire delta and coincident ground-based electrical resistance tomographic (ERT) and transient electromagnetic (TEM) data have been acquired at two locations, one along the delta's western margin and one in its north-central region. Inversions of the HTEM data have yielded three-layer resistivity models in which a relatively homogeneous conductive layer is sandwiched between two resistive layers. The three-layer HTEM model is reproduced in models obtained from independently and jointly inverting the ground-based data. The conductive layer's low resistivities and depths to its upper and lower boundaries are practically equal in the HTEM and ground-based models. Resistivities of the upper resistive layer are similar in the various models, with the ground-based estimates being somewhat higher than those of the HTEM model at one site and somewhat lower at the other site. For the basal resistive layer, it can only be concluded that its resistivity must be substantially higher than that of the overlying conductive layer. An interpretation of the HTEM and ground-based resistivity models in the delta's north-central region, appropriately constrained by the surface geology, high-resolution seismic refraction-reflection models, and borehole logs suggests the following structure: basement overlain at progressively shallower depths by freshwater-saturated sand and gravel that represent the remnants of a Paleo Okavango Megafan, saline-water-saturated sand, and lacustrine clay originally deposited in Paleo Lake Makgadikgadi, and freshwater-saturated megafan and fluvial sediments of the current Okavango Delta.

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Groundwater Exploration With Aem in the Boteti Area, Botswana

Cited by 24 publications

References 0 publications

Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California

Mapping Aquifer Systems with Airborne Electromagnetics in the Central Valley of California

Airborne and ground‐based transient electromagnetic mapping of groundwater salinity in the Machile–Zambezi Basin, southwestern Zambia

Hydrogeophysical investigations in the western and north-central Okavango Delta (Botswana) based on helicopter and ground-based transient electromagnetic data and electrical resistance tomography

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