The use of electrical conductivity mapping in the definition of an aquifer vulnerability index

Abstract

There is an increasing demand for vulnerability maps which show the degree of exposure of aquifers against pollution. Parameters shown in these maps are generally cation exchange capacity or clay content of the near surface layers, or quantities related to the infiltration time of surface water. Instead of determining these parameters by means of drillings and geological investigation, we propose the use of geophysical techniques for vulnerability mapping and for the interpolation between drillings. A geophysical quantity which is closely related to these parameters is the electrical conductivity. In this paper the relation between clay content and electrical conductivity is shown and used for vulnerability mapping. It is demonstrated that ground and airborne electromagnetic (EM) techniques are suited for large scale data acquisition.

Helicopter-borne transient electromagnetics in high-latitude environments: An application in the McMurdo Dry Valleys, Antarctica

“…For this reason, the TEM method and more generally, all induction EM methods have been intensively used for the mapping of conductive units. Hydrogeologic and resource applications of TEM include mapping clay-rich aquitards, which offer protections for aquifers (Palacky, 1987;Kirsch et al, 2003;Foged et al, 2014), seawater intrusion in coastal aquifers for water quality control and management (Kirkegaard et al, 2011;Teatini et al, 2011;Jørgensen et al, 2012) and mining exploration of highly conductive mineral deposits (Smith, 2014). Minsley et al (2012) use frequency-domain EM to map permafrost above groundwater in arctic Alaska.…”

Geophysical Assessment of Vulnerability of Surficial Aquifer in the Oil Producing Localities and Riverine Areas in the Coastal Region of Akwa Ibom State, Southern Nigeria

“…Effective porosity or permeability predicts the hydraulic resistance of argillaceous and arenaceous materials. In view of this, hydraulic resistance and effective porosity determine the electrical conductivity or resistivity of geological materials 3 . Therefore, hydraulic conductivity can be replaced either by resistivity  i or conductivity  i to estimate (C) known as integrated electrical conductivity (IEC) 25 , or a geophysical based index of protection 1 .…”

“…Based on this, protective layers that determine the protective capabilities of aquifers are known as homogenous layers. These bodies have coefficient of permeability and porosity as bulk properties 3 . Intrusion of sands or cracks in clay can cause non-homogeneities, which determine the pathways for percolation.…”

Laterally constrained inversion of helicopter-borne frequency-domain electromagnetic data

“…For more than a decade these Marquardt-Levenberg inversion (MLI) procedures have successfully been used for the interpretation of thousands of line-km of HEM data (e.g. Sengpiel and Siemon, 1997;Siemon et al, 2002;Kirsch et al, 2003;Siemon et al, 2004;Eberle and Siemon, 2006).…”