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The Application of Spectral Induced Polarization to Determination of Hydraulic Conductivity

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posted on 15.11.2021, 15:03 authored by Joseph, Sheen

Spectral Induced Polarization (SIP) is a geophysical technique that measures the frequency dependence of the electrical conductivity of a material. This thesis is an attempt to investigate the potential of using SIP as a proxy to predict the hydraulic conductivity of New Zealand shallow coastal aquifers. SIP measurements were made on sand samples that are typical of New Zealand coastal aquifers with a custom built impedance spectrometer and sample holder allowing the measurement of a phase difference as small a milliradian.  Even though the relaxation time shows a small dependence on pore fluid conductivity, especially at lower pore fluid conductivities, this variation is not serious enough to affect the hydraulic conductivity estimation at the field scale, but could be significant in the investigation of mechanisms that cause polarization in porous media.  Measurements on sieved fractions of sand established that there is an excellent correlation between the Cole-Cole relaxation time constant and grain size. The Cole-Cole relaxation time constant is very sensitive to the grain size distribution. Hydraulic conductivity predictions were attempted using various existing models. While the results are encouraging, it looks like there may not be a single universal model to predict hydraulic conductivity using SIP response.  When a correction term in the form of a multiplication constant is used, all the tested models seem to make very good predictions. But the constants calculated by fitting to the measured data could be applicable only to the type of materials studied. The dependence of the existing models on quantities like counterion diffusion coefficient, electrical formation factor and porosity makes hydraulic conductivity prediction challenging as these quantities are difficult to measure accurately in a field setting. Nevertheless it is concluded that SIP can be successfully applied to study hydraulic conductivity of New Zealand shallow coastal aquifers.

History

Copyright Date

01/01/2016

Date of Award

01/01/2016

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

Author Retains Copyright

Degree Discipline

Physics

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Doctoral

Degree Name

Doctor of Philosophy

ANZSRC Type Of Activity code

970102 Expanding Knowledge in the Physical Sciences

Victoria University of Wellington Item Type

Awarded Doctoral Thesis

Language

en_NZ

Victoria University of Wellington School

School of Chemical and Physical Sciences

Advisors

Ingham, Malcolm; Gouws, Gideon