Electronic Theses and Dissertations (PhDs)

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Browsing Electronic Theses and Dissertations (PhDs) by School "School of Geography, Archaeology and Environmental Studies"

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    Remote sensing survey of archaeological sites in the Shashi- Limpopo Region
    (2020) Thabeng, Olaotse Lokwalo
    The African continent is rich with archaeological heritage, which needs to be preserved for the current and future generations. The majority of archaeological heritage sites in Africa are facing disappearance due to a number of challenges including looting, destruction from developments, expansion of agricultural land and natural hazards. Documentation and monitoring of archaeological heritage sites, therefore, is of paramount importance for effective site management and preservation. However, archaeological heritage sites in the continent are poorly documented and monitored due to a number of factors including lack of funds by heritage management institutions, lack of trained personnel and inaccessibility of some areas due to conflicts or land ownership rights. Traditionally, the documentation and monitoring of archaeological heritage sites in Africa have been done through fieldwork, which is costly, time-consuming and difficult to carry out over large areas. Remote sensing offers a relatively fast, cheap, systematic and reproducible method of surveying and monitoring archaeological sites over large and/or restricted areas. Remote sensing techniques are used to identify earth surface features based on their spectral signature, which is the variation of reflection or emittance of materials’ electromagnetic energy. Spectral signatures for identifying archaeological sites are not universal, and an assessment of the applicability of remote sensing techniques in different archaeological landscapes is needed. The aim of this study, therefore, was to investigate the potential of using remote sensing techniques to document archaeological sites previously occupied by farming communities, which are traditionally associated with the Iron Age period in Southern Africa, using the Shashi-Limpopo case study. The first part of this study gives a review of the use of remote sensing in the African archaeological context. Despite it being a fast, cost-effective and systematic method of survey, the results of this study have demonstrated that remote sensing is not widely used in archaeological applications in Africa. The aforementioned situation calls for studies investigating the potential of using remote sensing techniques to fast track archaeological site survey, documentation and monitoring in the continent. The chemical composition of materials characterising different features have more or less subtle variations that, in turn influence the spectral behaviour of soil. This is an important principle that can be used for distinguishing archaeological soils from non-archaeological soils and can potentially help in discriminating different archaeological signatures. As such, the second part of this study investigated the possibility of using field spectrometer measurements to discriminate middens, non-vitrified dung, vitrified dung and non-sites (natural soils) characterising archaeological landscapes previously occupied by farming communities. It then investigated the presence of differences in the chemical composition of elements between middens, non-sites, vitrified dung and non-vitrified dung. The findings indicated that there is a statistically significant difference in the concentration of soil elements between non-sites, middens, vitrified dung and non-vitrified dung byres. They also indicated that some bands in the visible and shortwave infrared regions of the electromagnetic spectrum important bands for predicting the aforementioned archaeological sites and non-archaeological sites. In the third part of this study, the ability of multispectral sensors to discriminate archaeological and non-archaeological features in Shashi-Limpopo confluence area was investigated using field spectral data resampled to the spectral resolutions of common multispectral satellites namely GeoEye, Landsat 8 OLI, RapidEye, Sentinel-2, SPOT 5 and WorldView-2. This is because the spectral and spatial resolutions of various multispectral sensors determine the size and the type of archaeological data a sensor can detect. As such, another goal of this study was to identify multispectral sensors with the optimum spectral resolutions for detecting middens, non-vitrified dung, vitrified dung and non-sites. Additionally, the performance of advanced classification algorithms (random forest and support vector machines) in discriminating middens, non-vitrified dung, vitrified dung and non-sites was also investigated. The results proved the possibility of using multispectral satellites in mapping middens, non-sites, vitrified dung and non-vitrified dung sites. These results initiated the need to upscale the test to actual satellite images. The fourth part of this study assessed the possibility of prospecting for archaeological sites previously occupied by farming communities in the Shashi-Limpopo Confluence Area, using a very high-resolution satellite WorldView-2 image. The findings have shown that WorldView-2 satellite images and advanced classification algorithms can be used in prospecting for archaeological sites previously occupied by farming communities in Shashi-Limpopo Confluence Area. Finally, the ability of geographic object-based image analysis (GEOBIA) based on random forest and support vector machines, to discriminate archaeological and non-archaeological features on a very high-resolution satellite WorldView-2 image was investigated. The results of this study demonstrated the robust ability of the GEOBIA to integrate spatial attributes into the classification model improves the chances of separating materials with limited spectral contrast. Generally, this study has shown that remote sensing techniques can be used to map archaeological landscapes characterised by middens, non-vitrified dung, vitrified dung and non-sites. This will help archaeological heritage managers and researchers to document and monitor sites in archaeological landscapes characterised by the aforementioned features in a fast, systematic, reproducible and cost-effective manner
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    The political geography of hemp Cannabis in South Africa: A development critique
    (University of the Witwatersrand, Johannesburg, 2023-06) Moore, Wendell; Mnwana, Sonwabile; Wafer, Alex
    The discourse on Cannabis that is generally understood in the public domain, revolves mostly around its recreational uses and more recently its medicinal potential. The plants industrial usages and overall worth to society are often framed in relation to these more popular parts of Cannabis. The study focuses its attention on hemp Cannabis to tell a different story but acknowledges that all the uses of Cannabis are interlinked. Using an extensive desktop analysis, Cannabis webinars and conferences, as well as autoethnography, the thesis shows that there is in fact more to the plant than what first meets the eye. It especially illuminates two important dimensions of Cannabis that are often overlooked when discussing the plant. Firstly, by its nature Cannabis is political, which is deeply embedded in how the plant is understood in the geographic diaspora of the Global South. Secondly, it shows that any serious social scientific analysis of contemporary Cannabis development must think through how the ways of knowing, produced during prohibition, will become a part of the plant’s future. This thesis therefore argues for an appraisal and maintenance of the historical resistances of Cannabis used prior to legalization, if its development in the legal era is to be successful. To be sure, such innovative and alternative models of practical development should become a standard part of the geographies of all work economies. Moreover, making use of these forms of resistance is not about Cannabis gaining the approval from ‘the market’. In fact, the skills learnt while labouring for Cannabis, when it was prohibited, has become such a permanent feature of its development that liberal democratic consent is not an option. Therefore, the thesis proposes that Cannabis development delink from the prohibition narratives inscribed onto the plant. It continues by showing that the current medicalisation of Cannabis only updates gatekeeping models. Hence, an agrarian alternative was suggested that consolidates all the uses of Cannabis without undermining any one part of the plant. Lastly, the thesis documents the possibilities of gaining access into the industry for black people, the poor working class and women. What it argues is that ownership, just employment and leadership of Cannabis industries in South Africa must be repurposed so that ordinary people can also play a part in making sure the plants contemporary development is truly sustainable. Taken together, this is the critique of development that the political geography of hemp Cannabis in South Africa reveals.