Geophysical investigation of a freshwater lens on the island of Langeoog, Germany – Insights from combined HEM, TEM and MRS data

Costabel, Stephan; Siemon, B.; Houben, Georg; Günther, Thomas

doi:10.1016/j.jappgeo.2016.11.007

Cited by 36 publications

(29 citation statements)

References 44 publications

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“…The inaccuracy of the porosity estimates must be accepted as a natural consequence of the fact that some of the observed pores exceed the z dimension of the probed reference volume (e.g. Costanza-Robinson et al, 2011).…”

Section: Nmr-based Porosity Measurementsmentioning

confidence: 99%

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

Costabel

Weidner

Müller‐Petke

et al. 2018

Hydrol. Earth Syst. Sci.

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Section: Nmr-based Porosity Measurementsmentioning

confidence: 99%

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

Costabel

Weidner

Müller‐Petke

et al. 2018

Hydrol. Earth Syst. Sci.

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“…), and even the correlation of such TEM results from several neighboring sites allows the reliability to be improved. Therefore, simple approximate schemes for TEM data analysis have often been proposed [26,27].…”

Section: Discussionmentioning

confidence: 99%

An Express Algorithm for Transient Electromagnetic Data Interpretation

et al. 2020

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The transient electromagnetic (TEM) method is a time-domain, controlled source, electromagnetic (EM) geophysical technique which is often applied to image the subsurface conductivity distributions of shallow layers due to its effectiveness and adaptability to complex site working conditions. The means for an express analysis of such experimental data in several practical cases have advantages and are suitable for use. We developed our approach for determining the approximate one-dimensional (1D) model of background conductivity based on the formal transformation of the TEM experimental data and the mathematical analysis of continuous functions. Our algorithm, which allows the 1D model’s parameters to be obtained in terms of a layer’s thickness and resistivity, widely utilizes the numerical differentiation of experimental curves as well as of transformed ones. Since the noise level increases with time in the attenuating TEM signals and differentiation even enhances it, special procedures are required to calculate the derivative values. We applied the piecewise cubic spline approximation to solve this problem. In that case, the derivatives are obtained using polynomial coefficients which are available for each node. The application of the created facilities is demonstrated using real experimental data of the TEM soundings.

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“…A zone of electrically conductive water within an aquifer can have a similar appearance to a clay-rich geological body [25]. Although salinity mapping may be of concern in some hydrogeologic studies, in the analysis of hydrostratigraphic units, factors that influence permeability and groundwater flow are of chief concern.…”

Section: Discussionmentioning

confidence: 99%

Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

Korus

2018

Water

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Impermeable aquifer boundaries affect the flow of groundwater, transport of contaminants, and the drawdown of water levels in response to pumping. Hydraulic methods can detect the presence of such boundaries, but these methods are not suited for mapping complex, 3D geological bodies. Airborne electromagnetic (AEM) methods produce 3D geophysical images of the subsurface at depths relevant to most groundwater investigations. Interpreting a geophysical model requires supporting information, and hydraulic heads offer the most direct means of assessing the hydrostratigraphic function of interpreted geological units. This paper presents three examples of combined hydraulic and AEM analysis of impermeable boundaries in glacial deposits of eastern Nebraska, USA. Impermeable boundaries were detected in a long-term hydrograph from an observation well, a short-duration pumping test, and a water table map. AEM methods, including frequency-domain and time-domain AEM, successfully imaged the impermeable boundaries, providing additional details about the lateral extent of the geological bodies. Hydraulic head analysis can be used to verify the hydrostratigraphic interpretation of AEM, aid in the correlation of boundaries through areas of noisy AEM data, and inform the design of AEM surveys at local to regional scales.

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Geophysical investigation of a freshwater lens on the island of Langeoog, Germany – Insights from combined HEM, TEM and MRS data

Cited by 36 publications

References 44 publications

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

Hydraulic characterisation of iron-oxide-coated sand and gravel based on nuclear magnetic resonance relaxation mode analyses

An Express Algorithm for Transient Electromagnetic Data Interpretation

Combining Hydraulic Head Analysis with Airborne Electromagnetics to Detect and Map Impermeable Aquifer Boundaries

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