Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, School of Geosciences, 2017. / The costs of acid mine drainage (AMD) monitoring result in the quest for alternative noninvasive method that can provide qualitative data on the progression of the pollution plume and ground geophysics was the ideal solution. However, the monitoring of AMD plume progression by ground geophysics (time-lapse electrical resistance) proves to be noninvasive but also time consuming.
This study focuses on the modeling of different geophysical anomalies (mainly geoelectrical resistivity response) of the karstic aquifers. The models are generated from field parameters such as the electrical resistivity of the host rock and the target rock, depth to the target, noise level and electrode configuration in order to ensure that the model outcomes represent the actual field data. This process uses Complex Resistivity Model (CRMod) and Complex Resistivity Tomography (CRTomo) to generate geoelectric subsurface models. Different resistivity values are applied to targets in order to assess the difference against the baseline model for each target scenario. The resistivity difference is reduced to smallest possible value between the reference and new models in order to gauge the lowest percentage change in the model at which the background noises start to have impact on the results.
The study shows that the behavior of targets (aquifer) could be clearly detected through resistivity difference tomography rather than inversion tomography. The electrode array plays a significant part in the detection of target areas and their differences in resistance because of its sensitivity. This therefore indicates that the electrode array should be chosen according to study requirements. Furthermore, this study shows that the modelling of different target sizes, alignments and shapes plays huge role in the final results. Future studies that can provide a correlation between the field quantitative data from sampling and the model outcomes have the ability to add to the knowledge of geophysical modeling, thus reducing costs associated with field based plume AMD monitoring.
Key words: Acid mine drainage, geophysics, karst aquifer, complex resistance, modelling, tomography / XL2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/23591 |
| Date | January 2017 |
| Creators | Zulu, Sbonelo Mfezeko |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | Online resource (viii, 75 leaves), application/pdf |
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