HR: 13:55h
AN: H13G-02 INVITED     [Abstracts]
TI: Characterization of structures and transport processes in a heterogeneous aquifer using electrical conductivity and induced polarization imaging
AU: * Kemna, A
EM: a.kemna@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AU: Vanderborght, J
EM: j.vanderborght@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AU: Englert, A
EM: a.englert@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AU: Mueller, K
EM: k.mueller@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AU: Tillmann, A
EM: a.tillmann@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AU: Vereecken, H
EM: h.vereecken@fz-juelich.de
AF: Agrosphere Institute (ICG-IV), Forschungszentrum Juelich, Forschungszentrum Juelich, Juelich, 52425 Germany
AB: Transport processes in aquifers are strongly determined by the structure of the aquifer. Since the structure typically exhibits significant heterogeneity, conventional measurement techniques, such as local sediment or water sampling, are generally incapable of capturing the variability of structural parameters as well as the complexity of transport processes in heterogeneous aquifers. Among the variety of proposed geophysical methods for hydrologic system characterization at the field scale, in particular electrical imaging techniques are being considered powerful non- to minimally invasive tools to overcome this incapability. They can provide spatially and temporally highly resolved information on subsurface parameters which are closely linked to both structural and transport properties. The most promising approaches in this regard include, first, the time-lapse application of electrical conductivity imaging to characterize the spatio-temporal behavior of subsurface solute transport and, second, the application of induced polarization imaging for improved structural characterization. In the first case, transport properties, such as advection velocity and dispersivity, can be quantified by interpreting the time-lapse electrical imaging results by means of equivalent transport models. Complementarily, induced polarization imaging allows the direct assessment of pertinent structural properties such as characteristic pore size and hydraulic conductivity. Importantly, both approaches live on the availability and validity of certain, normally site-specific calibration relations, such as between solute concentration and associated bulk electrical conductivity change, or between internal surface area of the sediment and imaginary component of electrical conductivity. We investigated the value of both approaches by conducting cross-borehole field surveys at the Krauthausen test site, which bears a shallow heterogeneous aquifer. The direct structure characterization capabilities are examined by comparing electrical imaging results with structural information gained independently, for example from a series of cone penetration tests. To assess the transport characterization capabilities, different tracer experiments were conducted and monitored by time-lapse electrical imaging, the results of which are compared with results obtained from conventional multi-level sampling in monitoring wells. In addition, synthetic experiments have been conducted to critically elucidate the limitations of the methodological approach.
DE: 5109 Magnetic and electrical properties
DE: 5139 Transport properties
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting