Use of Airborne Hyper-Spectral Remote Sensing (HSRS) to Focus Remediation and Monitor Vegetation Processes on Gold Mining Landscapes in South Africa

Authors: Weiersbye, IM; Margalit, N; Feingersh, T; Revivo, G; Stark, R; Zur, Y; Heller, D; Braun, O; Cukrowska, EM Download Paper

DOI https://doi.org/10.36487/ACG_repo/605_52

Cite As:
Weiersbye, IM, Margalit, N, Feingersh, T, Revivo, G, Stark, R, Zur, Y, Heller, D, Braun, O & Cukrowska, EM 2006, 'Use of Airborne Hyper-Spectral Remote Sensing (HSRS) to Focus Remediation and Monitor Vegetation Processes on Gold Mining Landscapes in South Africa', in AB Fourie & M Tibbett (eds), Mine Closure 2006: Proceedings of the First International Seminar on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 601-611, https://doi.org/10.36487/ACG_repo/605_52



Abstract:
Gold has been mined from the Witwatersrand Basin for over a century at depths ranging from surface to over 4 km deep. Uranium has been similarly mined for over 50 years. Waste-rock and milled tailings are stored in unlined and mountainous tailings storage facilities (TSFs), most of which experience wall failures, erosion and seepage. Further transport of contaminants occurs via wind and water-borne pathways, and efflorescence of minerals from acid mine drainage (AMD) may be visible on soils many kilometres distant from the original source (Naiker et al., 2003). However, most contamination cannot be detected without detailed chemical investigations. Cost-effective methods for mapping contamination over large areas would assist in identifying potential risks, and help focus financial resources for strategic remediation. Accurate mapping of contaminant baselines before, and after, remediation would also allow environmental improvements to be visualized. Demonstrating environmental compliance is crucial for mines in South Africa, as lack thereof can lead to the loss of the mining permit, as well as failure to achieve mine closure. Earth observation systems on board satellites are widely used to map land-use, vegetation and some minerals. For example, the multi-spectral ASTER sensor on NASA’s TERRA satellite was used to map contamination around Johannesburg (Sutton et al., 2006). However, the spectral and spatial resolution of ASTER is too low for the detailed mapping that we require in our research program, which focuses on the use of vegetation to reclaim contaminated soils and groundwater. In contrast, airborne HSRS is characterised by high spectral and spatial resolution. We were especially interested in whether airborne HSRS could detect landscape processes associated with trees, and in whether HSRS would be suitable for monitoring the performance of different tree species planted to control acid mine drainage (AMD; Weiersbye et al., 2002). We tested the capacity of airborne HSRS at two altitudes for the mapping of vegetation, seepage and minerals on a range of semi-arid landscapes. Ground-truthing comprised geo-referenced and hand-held spectral readings of vegetation, soils, tailings, mineral efflorescence and other representative surfaces, followed by chemical and mineralogical analyses of samples. Airborne HSRS proved to be a consistent tool for the mapping of minerals, seepage and vegetation across a range of landscapes, provided that ground- truthing was adequate. This paper comprises an overview of the HSRS applications found to be achievable. Mine Closure 2006 ― Andy Fourie and Mark Tibbett (eds) © 2006 Australian Centre for Geomechanics, Perth, ISBN 0-9756756-6-4 Mine Closure 2006, Perth, Australia 601

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