Electronic Theses and Dissertations (PhDs)

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A geographical analysis of the impacts of construction and demolition waste on wetland functionality in South Africa: a study of Gauteng province
(University of the Witwatersrand, Johannesburg, 2024-09) Mangoro, Ngonidzashe; Kubanza, Nzalalemba Serge; Mulala, Danny Simatele
The purpose of this study was to investigate construction and demolition waste management processes in sub-Saharan Africa and how they affect wetland ecosystems, using South Africa as a case study. Construction and demolition (CDW) waste has become a massive urban environmental challenge on a global scale, but more so in developing countries found in sub-Saharan Africa. In the context of South Africa, construction and demolition waste is not a waste stream taken seriously by local and national authorities because it is ‘general waste that does not pose an immediate threat to the environment. This position is premised on the idea that construction and demolition waste is generally inert (chemically inactive) and therefore cannot cause an immediate environmental risk. In this study, it is argued that the environmental risk of waste goes beyond the embedded chemical constituencies because some waste streams can cause immediate environmental risk through their physical properties depending on the location of disposal. It is further argued that although CDW is generally inert, disposal in wetlands immediately disrupts the way wetland ecosystem’s function, causing several environmental risks. To mitigate the environmental threats posed by construction and demolition waste, this study proposes a change in the methodological approaches and strategies deployed to manage the waste stream, such as by introducing a hybrid of circular economy and industrial ecology to minimize or eliminate waste production. This study involved several data collection and analysis methods. Using a combination of qualitative and quantitative studies methods, data was collected with the goal to understand the perceptions of experts on how construction and demolition waste management in South Africa affects wetland ecosystems and what can be done to effectively manage the waste stream in the context of a developing country. Data informing this study were collected through semi-structured interviews and surveys in the province of Gauteng, specifically in the City of Johannesburg and City of Ekurhuleni Municipalities, where there is massive illegal dumping in wetlands for various reasons. Furthermore, apart from the use of semi-structured interviews and surveys, a digital elevation model was generated in ArcGIS Pro 10.1 software to measure the effects of construction and demolition waste on wetlands in the study area. The approach to this study using both qualitative and quantitative methods was crucial because it provided human perceptions which were accurately corroborated by GIS software. The study found that construction and demolition waste management in South Africa is affected by several challenges that lead to massive illegal dumping in critical ecological ecosystems such as wetlands. In a broad sense, the major challenge to sustainable construction and demolition waste management in South Africa is institutional failure at both the local and national levels. Local authorities such as municipalities are characterized by massive corruption, poor funding, and lack of strategic technologies among other things, while at the national level, there is massive interference with municipal affairs through bureaucratic delays in the disbursement of municipal funds. A combination of these and other factors leads to illegal dumping of construction and demolition waste across the Gauteng Province, particularly in wetlands in low-income areas. The data informing this study reveals that dumping construction and demolition waste in wetlands causes an immediate threat to the existence of wetlands through massive sedimentation with insoluble materials. It is ultimately found that construction and demolition waste destroy the ability of wetlands to offer ecosystem services such as flood attenuation, carbon sequestration, water filtration, and habitat provision, among other functions, leading to environmental events such as flooding. A combination of circular economy and industrial ecology can be one of the ways that can be deployed to effectively and sustainably manage construction and demolition waste in South Africa. The circular economy and its three principles of ‘reduce’, ‘recycle’, and ‘reuse’ has been successfully deployed in developed countries in the European Union, where recycling has topped 70% of the total construction waste generated. Industrial ecology with its analogy of industrial ecoparks has been deployed in the European Union with immense success, until more attention was directed to circular economy. With an increase in municipal funding and introduction of a construction waste information system, a combination of ‘circular economy’ and ‘industrial ecology’ can significantly help to reduce pressure on wetlands and the environment at large. Even though the methodological improvements suggested above could significantly reduce pressure on wetlands, the implementation could be faced with institutional challenges. Therefore, it is argued that urgent institutional transformation is required to make tangible changes in the field of construction and demolition waste management. It is recommended that there should be increased law enforcement to curb widespread illegal dumping in South Africa’s major cities. It is also recommended that, like in Europe, South Africa must introduce tailor-made legislation of policies for construction and demolition waste alone. Promulgation of dedicated legislation provides clear direction on how the waste stream is managed and who is responsible for specific roles. Furthermore, dedicated legislation can be a crucial tool to deliver sustainable construction and demolition waste management in South Africa because it can be used to encourage the use of recycled aggregates and limit the amount of illegal dumping or extraction of materials from the environment. Finally, dedicated construction and demolition waste legislation can be used to shift from the traditional view of pollution or contamination through toxicity, and so the value of this study is immediately apparent.
A GIS framework for the integrated conceptualisation, analysis and visualisation of Gauteng's complex historic and contemporary post-mining urban landscape
(University of the Witwatersrand, Johannesburg, 2023) Khanyile, Samkelisiwe; Esterhuysen, Amanda; Kelso, Clare
This research study applies assemblage theory as a philosophical lens. It proposes a framework for integrating contemporary and historical landscape characteristics of post-mining and urban landscapes for an integrated conceptualisation, mapping, and analysis of Gauteng, South Africa. The study utilises a mixed methods approach, incorporating spatial and non-spatial (literature and survey) data of varying formats to identify landscape characteristics. Additionally, it applies three multicriteria decision analysis (MCDA) and GIS mapping techniques, employing a simplified rationale to keep its complexity low. Descriptive and inferential statistics were used to analyse the quantitative data, while the qualitative data was analysed using a thematic analysis. The literature and survey analysis findings were used to inform the development of a framework demonstrating the integration of Gauteng's post-mining and urban landscape characteristics using a fuzzy overlay, weighted overlay and random forest classification, along with an accuracy assessment of the mapped results. Based on the proposed framework, the mapped results' performance was evaluated through four methods: confusion error matrix, cross-evaluation, areal coverage comparison, and an image differencing assessment. The literature and survey analysis findings, used to inform the framework, reveal that the two landscapes consist of an assemblage of characteristics and highlight differences in the characterisation of post- mining and urban landscapes. Distinctions were also apparent between literature-derived characteristics and those identified from local experts. The local expert-derived characteristics demonstrate context- specific characteristics of Gauteng's post-mining and urban landscape. At the same time, those based on the literature emphasise a more distinct and separate portrayal of post-mining and urban landscape characteristics (pages 115-116). The characteristics identified from local experts were less conservative (pages 117-118). They included urban-related characteristics in the description of post-mining landscapes and mining-related characteristics in the description of urban landscapes, presenting some similarities in the characterisation of these two landscapes in Gauteng. Moreover, the findings from local experts also revealed that literature and other written or mapped work informed most definitions of post-mining and urban landscapes. The framework for integrating landscape characteristics (pages 121-123) was spatially represented through the three mapping methods, visually demonstrating several findings providing insight into the Gauteng landscape's uniqueness. First, it demonstrates that the differences in the characterisation of these landscapes also impact how they are spatially represented. The maps of post-mining and urban landscape characteristics based on the literature presented a similar pattern to the traditional mapping of mining and urban landscapes in Gauteng. These mapping techniques show the highest values across the mining belt and at the province's core. These findings highlight the influence of literature on the representation of these two landscapes, which is consistent with local experts' reports. In all three mapping methods, the maps generated from local expert characterisations of post-mining and urban landscapes presented a larger spatial footprint than those based on literature-derived characteristics. This distinction was attributed to incorporating additional post-mining and urban landscape characteristics in the maps based on expert input and applying the three mapping techniques - using representation methods not commonly used in mapping these landscapes. Second, the integrated maps of post-mining and urban landscape characteristics suggested a variance in the presence of post-mining and urban landscape characteristics across the province in the maps generated using fuzzy and weighted overlay techniques. This indicates that some parts of the province have a higher or lower presence of post-mining or urban characteristics (pages 125-132). These findings were visible in the maps generated from literature and local experts, indicating the diversity of both landscapes and the co-existence of post-mining and urban landscape characteristics in the local expert maps. This implies an intricate relationship between these landscapes, challenging the idea of them being strictly separate, as indicated in maps presenting characteristics identified from the literature. Furthermore, a closer inspection of the areas showing the intersection between post-mining and urban landscape characteristics also points towards the porosity of boundaries of these two landscapes and alevel of spatial overlap, organisation and arrangement, which are prevalent at varying levels (pages 164- 168). Third, the maps generated using literature-derived characteristics achieved higher accuracy scores, attributed to using reference data traditionally used to map the two landscapes under investigation. This reference data only comprised classes that characterised the physical mining and urban classes, consistent with those identified in the literature. Consequently, it lacked additional factors characterising the post-mining and urban landscape identified from local experts. The fuzzy overlay maps informed by literature demonstrated an accuracy exceeding 70% for post-mining and urban landscape characteristics. In comparison, those reported by local experts scored 64. The weighted overlay and random forest classification resulted in accuracy rates exceeding 50% for post-mining landscape characteristics maps, regardless of whether literature or expert-derived characteristics were used. Additionally, urban landscape characteristics maps achieved an accuracy of over 76%, regardless of the characteristics used to inform the mapping. These findings were attributed to the different mapping techniques employed, with fuzzy and weighted overlay using a gradual range scale, while random forest classification employed a binary scale. This highlights how different mapping methods affect the representation of space. Additionally, it demonstrates the versatility of these mapping techniques in mapping complex spaces such as post-mining and urban landscapes. In this study, the fuzzy overlay accuracies exceeded 60% for all maps and emerged as the most suitable choice for integrating landscape characteristics due to its ability to represent blurred and porous boundaries between Gauteng's post- mining and urban landscapes. In conclusion, the study challenges the notion of post-mining and urban landscapes as distinct landscapes, emphasising the importance of considering the varying levels of spatial intersection between these two landscapes. With the proposed framework and the alternative representation of these landscapes, including contextual information, this research provides insights into new conceptualisations of urban, post-mining landscapes and mineralised urbanisations as assemblages of different landscapes and characteristics with porous boundaries. This enables a better understanding of Gauteng's post-mining and urban landscapes, which could benefit the representation, communication and management of these landscapes. Recognising the potential applications and limitations of frameworks such as the one developed for this study, the high-level recommendation arising from this study suggests a need for ongoing research into the contextual representation of landscapes and their characteristics. This can be achieved by incorporating input from communities, conducting research on quantifying intangible landscape characteristics and developing tools that facilitate the automation and alignment of such data with development plans.
Assessing livelihood vulnerability and adaptation to climate variability and change among farming households in Plateau State, north-central Nigeria
(University of the Witwatersrand, Johannesburg, 2024) Hassan, Buhari; Knight, Jasper
It has been projected that sub-Saharan Africa would be severely affected by climate change in form of persistent and increasing climate variability. Nigeria’s situation as a developing country coupled with the fact that agricultural activities are primarily rainfed, provides a suitable case study in which to assess the vulnerability of farming households to climate variability and change. Lack of data on the nature and extent of vulnerability to climate variability (particularly annual changes in rainfall and temperature patterns) on food production systems and livelihoods in Nigeria hinders the development of effective policies to mitigate the adverse impacts of climate change and variability. The study aims to improve understanding of the socio-economic, institutional, biological and physical factors that contribute to vulnerability of farming households to climate change and variability in Nigeria. By combining descriptive, participatory and statistical analysis as well as field observations, this research develops a holistic approach to assess the level of exposure, sensitivity and adaptive capacity of farming households. Multistage sampling was used to purposely select communities in Bokkos Local Government Area, Plateau State, for the study, while farming households were randomly selected for the household questionnaire survey within four communities. Purposive sampling was used to identify key informants for interviews. Observation and taking photographs of farmers’ activities were used to complement the other data collection methods. Qualitative data was analysed using descriptive and content analysis, while the quantitative data was analysed using the Statistical Package for Social Sciences (SPSS) (v 27) and Microsoft Excel (v2020). The level of vulnerability of farming households was determined using the Sustainable Livelihood Approach. Results show that farmers are exposed to climate variability in form of changing rainfall patterns which includes late onset of rains, dry spells, and early cessation of rains and crop loss due to pests and disease infestation. Results show that the vulnerability of farming households can be linked to access to household livelihood capital assets and that households are characterised by low levels of financial, social and physical capital. Smallholder farming households adopt a range of on-farm and off-farm adaptation strategies including changing planting time, crop diversification, engaging in irrigation farming, intensifying the use of fertilizers, manure and agro-chemicals to boost crop yield, and planting of disease-resistant and drought-tolerant crop varieties. Farming households experience a number of challenges which include a lack of financial resources which has a strong influence on enhancing other capital assets such as physical and natural capitals; poor access to mechanised agricultural equipment, lack of training on how to deal with climate change and variability, limited access to improved crop varieties as well as a lack of institutional support, which constitute serious barriers to adaptation to climate variability. In applying these results to climate change adaptation it is recommended that policymakers need to institute specific and implementable climate change adaptation policies that will enable farmers to utilize their capital assets on effective adaptation measures and also engage in viable alternative livelihood diversification strategies, enhance agricultural productivity and resilience and improve institutional support including access to information and training
Assessing the inter-annual and inter-seasonal climate-induced variation in caseload of respiratory diseases
(University of the Witwatersrand, Johannesburg, 2024-06) Motlogeloa, Ogone
In South Africa, acute upper respiratory diseases pose a significant public health challenge, influenced heavily by climatic factors. Recognizing the critical need for detailed seasonal analysis. This thesis delves into the inter-annual and inter-seasonal impacts of climate on disease caseloads, offering four pivotal contributions to health biometeorology. The first contribution refines the understanding of the acute upper respiratory disease season in South Africa, previously recognized as the winter months of May to September. This research provides a more granular analysis by pinpointing specific onset timings and fluctuations within the season that are crucial for optimizing healthcare responses, particularly in vaccination schedules. The second contribution is an in-depth analysis of climatic variables affecting acute upper respiratory disease prevalence. Utilizing Spearman's correlation analyses and the Distributed Lag Non-linear Model across Johannesburg, Cape Town, and Gqeberha, this study identifies negative correlations between temperature and disease cases, pinpointing significant risk thresholds most prevalent during the winter peak. The third contribution investigates the impact of extreme climate events (ECEs) over twelve years, elucidating how, while individual ECEs influence medical aid claims and disease incidence, it is the broader seasonal patterns that predominantly dictate acute upper respiratory disease prevalence. The fourth contribution offers a nuanced exploration of the climate-health nexus, demonstrating that routine weather variations play a more significant role in the peak transmission of acute upper respiratory viruses than extreme events. This thesis elucidates the substantial yet nuanced influence of climate on respiratory health in South Africa. By specifying the disease season with greater precision and clarifying the relationship between temperature variations and disease prevalence, the research provides essential data for health practitioners to plan targeted interventions. This study moves beyond the focus on extreme weather events to expose the subtler, yet more consistent, impact of seasonal climate shifts on health outcomes, enriching our understanding and serving as a vital reference for enhancing disease preparedness in an era marked by climatic uncertainty.
Cartographic History, the Post-Colonial Landscape and the Agricultural Settlement Scheme: A Case Study of Citizen-Based Mapping in Northeastern Ibadan Rural Hinterland
(University of the Witwatersrand, Johannesburg, 2023-10) Ogundiwin, Babatunde Adedayo; Wafer, Alex
Maps of economic imagination provide visual insights into alternative agrarian spatial thought. This thesis examines visual contribution to reconstituting agricultural subjectivity. It explores the potential of citizen-based mapping in consolidating alternative visions of the agricultural settlement scheme. Visualisations are integral in the discursive technologies of post-colonial state policies that produce modern agricultural subjectivity. On one hand, these state cartographic strategies involve othering practices of subaltern agriculture. On the other hand, there are resurgent ideas of community-based agricultural schemes verbalised amongst subaltern groups. Hence, there is an ongoing political-economic struggle of visions mediated by visualisation and verbalisation. Drawing upon theoretical literature in spatiality, postcolonialism and governmentality, the thesis explores taken-for-granted knowledge, sites of economic difference and silenced voices/visions on the post-colonial agricultural landscape. Using Northeastern Ibadan rural hinterland of Oyo State, Southwest Nigeria, as a case study, the thesis argues that visualisation offers insight into counter-narratives and alternative reframing of the agricultural settlement scheme. This study employed a multi-method qualitative approach involving the critical historical reading of state maps, ethnographic analyses and mapmaking techniques to visualise and summarise developmental concerns and aspirations. The thesis demonstrates that state imaginative geographies strive in shaping agricultural identities and subjectivities. Recently, these cartographic legacies of state rationalities seek the active consent of the citizenry in the drive toward state-sanctioned neoliberal imaginary. The study contends that the post-colonial state in Nigeria envisions a large-scale agricultural development rather than supporting smallholder subaltern agriculture. Hence, there is intentional and unintentional involvement in visual disinformation and engagement in anti-political economic imaginations of subaltern agriculture. However, the visualisation of verbalised counter-narratives contesting state developmental visions and alternative imaginations of the agricultural settlement scheme unveil anticipatory spatialities desiring a break from economic decline and stagnation in rural hinterlands. This transformation of imaginaries into visual images emphasises new perspectives and new insights renegotiating the political subjectivity of subalterns. This thesis demonstrates that visual geographies of subaltern aspirations offer alternative visions of the agricultural settlement schemes.
Climate Variability and Asset Adaptation of Small-scale Farmers in Zimbabwe's Gokwe South District:A Search for Knowledge Integration Approach
(University of the Witwatersrand, Johannesburg, 2023-05) Chatsiwa, Jaison; Simatele, Mulala Danny
Globally, climate change and variability threaten food production and security for an unforeseeable future leaving millions of people vulnerable to hunger and malnutrition related diseases. Climatic models are projecting that Zimbabwe’s climate will be hanging drastically with a high possibility of experiencing extreme weather patterns impacting the livelihoods of small-scale farmers who rely on rain-fed agriculture for their livelihoods. This study aims to investigate the role of asset portfolios in reducing the climate vulnerability of small-scale farmers of Gokwe South in Zimbabwe. Zimbabwe’s agricultural production both crop and livestock production has been negatively impacted due to the dwindling rainfall and increase in temperature and climate related risks and disasters. The quality and quantity of asset portfolios determine the adaptive strategies and their success against the challenges of climate variability. Despite these effects, small-scale farmers in the Gokwe South district are using their asset portfolios to increase their adaptive capacity and resilience to fight against the challenges of climate variability. Therefore, this thesis revealed a paradigm shift from asset vulnerability to pro-poor asset adaptation. The paradigm shift crafted the ‘Theory of Change’ which is useful for climate variability adaptation strategies in the Gokwe South district as the small-scale farmers change from asset vulnerability to asset adaptation. The Theory of Change encourages contextual analysis of the area and theme under study. A Theory of Change is a method that explains how a given intervention, or set of interventions, is expected to lead to specific development change, drawing on a causal analysis based on available evidence. This study used the Participatory Climate Change Adaptation Appraisal (PCCAA) as the primary data collection tool and the Participatory Rural Appraisal (PRA) known as the emancipatory methodology, to collect data in rural areas. A mixed methodological approach involving qualitative and quantitative was applied. We used thematic content analysis to analyse qualitative data collected during the data collection exercise. During the study period, computer-Aided Qualitative Data Software was used to store data in a sorted manner. The parametric variables were coded using the Predictive Analytic Software. This enabled to performance of statistical analysis and obtaining descriptive statistical outcomes were obtained. The assessment of the effect of the factors on climate adaptation strategies was done through the Likert scale. Indigenous knowledge remained widely used as a source of climate knowledge in the Gokwe South district. The research results showed that indigenous knowledge (IK) is unpredictable, productive assets and adaptive assets are inadequate, technoscience and institutional support are poor support to implement viable adaptation strategies is lacking, and poor distribution and dissemination of climate and weather information to small-scale farmers in the Gokwe South district is poor and asset portfolios and asset mix is poor. The available asset portfolios determine the adaptation strategies used in the Gokwe South district. Results show that climate vulnerability varies spatially and temporally across the Gokwe South district. The studied five constituencies for the Gokwe district have a mean vulnerability index of 3.04 with the highest index being 5 as being well adapted. Sengwa and Mapfungabutsi are highly vulnerable to the vagaries of climate variability in the Gokwe South district. The researchers recommend strong institutional support from the government. The fact that small-scale farmers should integrate their IK and modern science climate knowledge small-scale farmers in the Gokwe South district should adopt proactive or anticipatory adaptation, government climate-smart agricultural policies, and a bottom-up approach to climate variability. The quality and quantity of asset portfolios are key resources affecting the level of vulnerability to climate variability. The asset mix was seen to be significant in reducing the vulnerability of small-scale farmers in Sengwa and Mapfungabutsi, constituencies worst affected due to poor asset endowment of farmers in the Gokwe South district. The results have shown that the financial asset is the most important asset affecting vulnerability because it can be converted into other assets through buying. Weak institutional intervention renders many small-scale farmers helpless to climate variability, and the government is not fully supporting small-scale farmers to increase their adaptive capacity and resilience.
Compost-assisted phytoremediation of mine tailings and footprint areas using chrysopogon zizanioides (l) roberty enhanced with moringa leaf extract biostimulant in the Witwatersrand goldfields of South Africa: a sustainability initiative
(University of the Witwatersrand, Johannesburg, 2024) Mlalazi, Nkanyiso; Chimuka, Luke; Simatele, Mulala Danny
In the Witwatersrand goldfields of South Africa, mine tailings and footprint areas are significant environmental problems because they are major sources of toxic metals. These metals can leach into soils, and both surface and ground water, causing serious risks to human, animal, and plant life. In this study, the compost-assisted phytoremediation of tailing storage facilities (TSFs) and footprint soil using Chrysopogon zizanioides (vetiver grass) enhanced with moringa leaf extract (MLE) was investigated. A greenhouse experiment was conducted to identify the most favorable parameters, and was followed by a field study to test the optimized parameters under real-environment settings. For the greenhouse experiment, a 3×2×2 fully crossed factorial design was used to determine the optimum variables. Vetiver growth was assessed under three compost concentrations (0%, 30% and 60%), two types of MLE (laboratory extracted MLE and commercial MLE) and two application regimens (once a week and twice a week) were used. The biomass and metal concentrations in the vetiver grass roots and leaves were measured after sixteen weeks followed by a two-way ANOVA analysis and the post-hoc tests. All the vetiver that was planted in 0% compost died within four weeks regardless of the MLE treatment. Vetiver grass planted on the 60% compost amendments and sprayed with laboratory extracted MLE had the highest biomass production, followed by plants grown in 30% compost amendments and sprayed with commercial biostimulant. However, the heavy metal removal or uptake data by the plant was inconclusive, as most of the toxic metals were not removed by vetiver grass which was attributed to the effect of compost. Based on biomass data, the 30% compost amendment and commercial bio-stimulant was the ideal treatments for the phytoremediation of gold mine tailings using vetiver grass. Although metal accumulation by plants is one of the attributes considered in phytoremediation, it is not the most significant factor in the phytostabilisation process. Plant growth and biomass production are the most significant, therefore it is concluded that vetiver, MLE and compost can be used in the phytostabilisation of gold mine tailings, however reduction in compost may be considered in future to improve the accumulation of metals in the roots for improved results. Following the conclusion of the greenhouse study, a field study was conducted during the rainy season of 2021. Two field experiments were carried out concurrently at two sites: the footprint area (that was used as a rock dump) and the tailings storage facility (TSF 4). A split-plot design was used in this study. The experiment at each site assumed a 3×1×2 factorial design, with three levels of compost treatment (0%, 15% and 30%), 1 level of vetiver cultivar (Chrysopogon zizanioides), and 2 levels of MLE treatment (commercial MLE and tap water, both sprayed once a week). Three blocks measuring 1 m × 2 m, each with 20 holes filled with equal amounts of soil amended with the different compost levels were prepared in triplicates. A single vetiver grass slip was planted in each hole. The blocks were then divided into 2 sections, each with 10 holes, and commercial MLE was sprayed on one section, while only water was sprayed on the other section once a week. After sixteen weeks, three plants were harvested from each section and the number of leaves, leaf length, number of tillers, biomass for roots and leaves and element concentrations were measured. Data analysis was done using two-way ANOVA
From Coal to Renewable Energy: Perspectives on South Africa's Energy Transition for a Sustainable Future.
(University of the Witwatersrand, Johannesburg, 2024) Sebele, Temperance; Simatele, Mulala Danny
South Africa has been experiencing an unstable electricity supply for years, leading to periods of load shedding from 2007 up to the present date. The electricity shortages have been attributed to distinct reasons, ranging from inefficient coal supply, skills shortages, sabotage by employees and lack of maintenance for nearly sixteen years. In addition to the electricity supply shortages, coal-fired electricity generation is responsible for roughly 80 per cent of South Africa’s total greenhouse gas emissions due to fossil fuel dependence, leading to many health, climate, and environmental challenges. To address the challenges related to fossil fuel dependency, moving to Renewable Energy sources that are climate and environmentally friendly is a necessity. The aim of this study was to investigate the optimal approaches that South Africa can embark on for a successful transition from coal to renewables. The institutional, policy, and strategic frameworks that exist within which South Africa can embark on for a successful transition were explored. Furthermore, the study sought to identify the challenges, and opportunities that exist or hinder the transition in South Africa. Lastly, the study explored how developments in the international policy frameworks influence South Africa’s ambitions to transition to renewables. The study is best suited to the pragmatism approach, and data were collected through the reviewing of literature, key-informant interviews, and questionnaires. A mixed-methods strategy that involved gathering both qualitative and quantitative data was employed and primary and secondary sources of data were used. The primary data sources used included key informants from various private and public institutions with an interest in South Africa’s energy matters such as ESKOM, SANEDI, SANEA, SAREC, SAPVIA, SAWEA, SAIPPA and NECSA. The non-probability sampling method was used in the participants’ selection from the sampled study institutions, with a combination of judgmental, snowballing and convenience sampling procedures employed at distinct phases of the research. Data collected was analysed both quantitatively and qualitatively, with interviews text data transcribed and analysed through manual tabulation and thematic analysis, and presented in graphs generated from Microsoft Excel, and the data from questionnaires analysed through the IBM Statistical Package for the Social Sciences (SPSS) software. The study revealed that the government played mainly four leading roles in the energy transition, which were providing financial support, legislative direction, institutional direction, and project oversight. Financial support is provided through financing projects and setting up financing policies that promote renewable energy investment, and legislative direction is provided through policy development and ensuring efficient implementation. Providing institutional direction is ensured through ensuring coordination across all spheres of government and capacitating institutions involved in the transition, and project oversight is provided through setting out renewable energy capacity determinations. The study further identified key energy transition elements, namely infrastructure, governance, legislation, stakeholders’ perceptions, and skills and strategies for a successful transition, which included channelling adequate financial resources to the renewable energy sector, privatisation of the electricity utility, diversification, rolling out bid windows, improving the legislative framework, improving grid access and integration, skills development, localisation of RE components manufacturing, providing incentives, and increasing consumer awareness about renewables. Several barriers to the transition were also identified, which included political interference and corruption, lack of financial investment, policies/legislation inadequacy, inconsistency in rolling out bidding windows, ESKOM’s monopoly, high cost of renewables, deficiency of incentives, skills and technology, labour unions, and deficiency of awareness on alternatives. The study recommends multisector reskilling of employees, since not all employees in the coal value chain may be interested in or able to be absorbed in the Renewable Energy sector. Furthermore, the government should fund and support progressive technologies and business models, improve the quality of institutions through merit-based appointments and uprooting corruption, privatisation of ESKOM to create opportunities for new entrants in the electricity market and improve stakeholder engagement and community support programmes. The UNFCCC must develop and ensure the implementation of enforcement strategies for holding countries accountable for their climate commitments for the transition to be realised
Integrating Sentinel-1/2 and machine learning models for mapping fruit tree species in heterogeneous landscapes of Limpopo
(University of the Witwatersrand, Johannesburg, 2024-10) Chabalala, Yingisani Winny; Adam, Elhadi
From ancient times to this century, Africa has relied chiefly on agriculture for survival. Crop type maps are crucial for agricultural management, sustainable farming systems, and realizing food security. Agronomists, agricultural extension officers, policymakers, and the government rely on crop type spatial distribution information to make informed decisions and optimize resource allocation for sustainable agricultural management. Attaining food security for all is an urgent need in Africa. However, the farming landscapes predominately comprise fragmented smallholder heterogeneous farms. The farming systems include intercropping and cultivating different crops that require different management strategies. This results in within-class spectral similarities and intra-spectral variability due to similar canopy structures and different phenologies, which complicates the application of remote sensing in crop type mapping. The free availability of Copernicus products such as Sentinel 1 and 2 have high temporal, spectral, and spatial resolution suitable for mapping smallholder agriculture. Thus, this research aimed to integrate Sentinel-1/2 and machine learning models for mapping fruit tree species in heterogeneous landscapes of Limpopo. First, the research tested the applicability of sampling techniques and five mapping classifiers (i.e., Random Forest (RF), Support vector Machine (SVM), Adaptive Boosting (AdaBoost), Gradient Boosting (GB), and eXtreme Gradient Boosting (XGBoost) in mapping fruit trees and co-existing land use types. The original dataset was under-sampled randomly into two balanced datasets (i.e., Dataset 1 and Dataset 2) consisting of 100 and 150 sample points. Furthermore, the imbalanced ratio from the original dataset was reduced by applying different sampling strategies to extract four imbalanced datasets (i.e., at 40%, 50%, 60%, and 70%), which resulted in the formation of Dataset 3, Dataset 4, and Dataset 5, respectively. These samples, together with the original dataset (i.e., Dataset 7), were used as input to Sentinel‑2 (S2) data using adaptive boosting (AdaBoost), gradient boosting (GB), random forest (RF), support vector machine (SVM), and eXtreme gradient boost (XGBoost) machine learning algorithms. The results showed that reducing the amount of imbalanced ratio by randomly under-sampling the original imbalanced dataset could increase the classification accuracy to 71% using the SVM classifier and 60% of the original dataset. Individually, the majority of the crop types were classified with an F1 score of between 60% and 100%. Secondly, the research independently assessed the effectiveness of Sentinel-1 (S1) and Sentinel-2 (S2) data for fruit tree mapping using random forest (RF) and support vector machine (SVM) classifiers. Four models were tested using each sensor independently and fusing both sensors. From the fused model, features were ranked using the RF mean decrease accuracy (MDA) and forward variable selection (FVS) to identify optimal spectral windows to classify fruit trees. The best fruit tree map with an overall accuracy (OA) of 0.91.6% with a kappa coefficient of 0.91% was produced using the RF MDA and FVS model and SVM classifier. The application of SVM to S1, S2, S2 selected variables and S1S2 fusion independently produced OA = 27.64, Kappa coefficient = 0.13%; OA= 87%, Kappa coefficient = 86.89%; OA = 69.33, Kappa coefficient = 69. %; A = 87.01%, Kappa coefficient = 87%, respectively. The green (B3), SWIR_2 (B10), and vertical horizontal (VH) polarization bands were identified as the optimal spectral features for S2 and S1 data, respectively. The third part of the research identified the optimal growth window period in which fruit trees can be detected with high accuracy. Phenological metrics were extracted from 12 months (i.e., January to December) of Sentinel-2 (S2) data and were used to classify fruit trees using a random forest (RF) classifier in a Google Earth Engine environment. The results showed that fruit trees can be detected and mapped with high accuracy during winter months (i.e., April-July) with an overall accuracy (OA) of 84.89% and a kappa coefficient of 83%. The user accuracy ranged from 62 to 100%, while the producer accuracy ranged from 60 to 100%. The fruit trees were mostly differentiated from co-existing land use types using the short infrared and the red-edge bands. The fourth part of the thesis attempted to increase fruit tree classification accuracy by classifying optimal Sentinel-2 images acquired during the fruit trees' critical growth stages using a Deep Neural Network (DNN) model. This was achieved by applying phenological metrics derived from Sentinel-2 images acquired during optimal crop-growing seasons (i.e., flowering, fruiting, harvesting). The DNN models were optimized by tuning the hyperparameters to achieve the best classification results. The DNN produced an OA of 86.96%, 88.64%, 86.76%, and 87.25% for April, May, June, and July images, respectively. The results indicate the DNN models were robust and stable across the selected fruit growth periods. This research has shown that earth observation (EO) data such as Sentinel 1 and 2 can be used to map fruit trees in fragmented sub-tropical horticultural landscapes characterized by different environmental conditions and different crop cultivars operating under different management practices. The research results will assist agricultural stakeholders (i.e., farm managers, agronomists, agricultural extension officers, and policymakers) in allocating agricultural resources, devising effective agricultural management strategies, and attaining sustainable agriculture and food security.
Integration of Sustainable Development Principles and Climate Change Adaptation Measures in Energy Optimization in Gold Mining in South Africa
(University of the Witwatersrand, Johannesburg, 2023-08) Nadunga, Irene; Simatele, Mulala Danny
South Africa located in the sub-Saharan African region and being a mining-intense country, is reported to be affected by extreme weather events which are increasing the country’s vulnerability to climate change impacts and therefore reducing the chances of achieving sustainable development. In light of this, mining companies are being pressured to make strong commitments towards implementation of sustainable development principles for sustainable mining. This study therefore aimed at investigating how sustainable development principles and climate change adaptation measures are interlinked and structured; and embedded in a gold mining company’s policies and strategies, in an effort to build the mining operations’ adaptive capacity and resilience against the impacts of climate change and achieve energy optimization. The challenges that can potentially prevent the effective integration of the sustainability principles and adaptation measures were also explored. Using a case study approach, this study was centered on the gold mining operations located within the Witwatersrand Basin of South Africa. Research data was collected from multiple sources, therefore employing a mixed method approach by applying the concurrent triangulation technique. Different analytical tools of policy, content and inductive data analysis, and descriptive statistical data analysis were applied. The empirical evidence shows that the gold mining operations are faced with increasing operating costs associated with the increased energy consumption and implementation of costly mining practices in an effort to combat the impacts of extreme weather events caused by climate change. This affirms that a relationship exists between climate change and energy use in gold mining. In an effort to address climate related risks and energy security, gold mining operations are implementing energy efficiency measures and using renewable energy in their energy mix; which measures are seen to integrate sustainability principles, therefore adopted as sustainability adaptation measures. In addition, some mining company policies and strategies are also seen to integrate sustainability principles and adaptation measures, in an effort to guide the mining operations in effectively developing and implementing sustainability adaptation measures, designed to holistically address climate related risks and energy security. This affirms that a relationship exists between sustainable development principles, climate change adaptation measures and energy optimization. This therefore, implies that sustainability principles and adaptation measures can be integrated to form sustainability adaptation measures, and that gold mining companies have the potential to achieve sustainable mining and contribute to sustainable development, particularly achieving SDG 7 and SDG 13.
Mapping and assessment of informal settlements using object-based image analysis, a case study of Mamelodi, Tshwane, South Africa
(University of the Witwatersrand, Johannesburg, 2024) Mudau, Naledzani; Mhangara, Paida
The social and environmental challenges faced by people living in informal settlements or slums are widely recognized by development agendas including United Nations Sustainable Development Goals, Agenda 2063 and National Development Plans. The study aims to investigate informal settlement dynamics and spatial characteristics to generate an understanding of housing informality and environmental conditions for designing innovative sustainable solutions. The study assessed the use of 12 spectral indices and textural measures, and object-based image analysis (OBIA) technique to detect informal settlements from WorldView 2 images. A growth indicator that uses informal settlement extent and impervious surface was developed and used to assess informal settlement growth patterns between 2005 to 2020. Unmanned aerial vehicle image products, and landscape metrics were used to assess the spatial characteristics and patterns of backyard shacks and free-standing informal settlement structures. In addition, a settlement surface ecological index was developed and used to assess the ecological conditions of informal settlements. Lastly, the assessment of the location characteristics of informal settlements was done using ancillary data. The results show that the use of built-up index, coastal blue index and first order statistics mean textural measures and OBIA technique detected informal settlements with producer and user accuracies of 95% and 82% respectively. The developed informal settlement growth assessment indicator shows that informal settlement in 2020 had a slightly lower density of impervious surfaces than in 2005. The Euclidean Nearest-Neighbour Distance, Aggregation Index and Cohesion Index show that backyard shacks are less connected, less dense, and more isolated than freestanding informal settlement structures. Some informal settlements have better surface ecological conditions than some of the formal settlements. A higher extent of informal settlements continued to develop closer to formal settlements, rivers and railway lines between 2015 and 2020. The information demonstrated in this study can be used by local authorities to better understand and manage informal settlement developments, prioritize settlement upgrade projects and improve the environmental conditions and resilience of informal settlements
Palynological insights into an 11,700-year sequence of vegetation change in mashishing, Mpumalanga, northeastern South Africa
(University of the Witwatersrand, Johannesburg, 2023) Olatoyan, Jerry O.; Schoeman, Alex; Neumann, Frank; Sievers, Christine; Orijemie, Emuobosa; Evans, Mary
In this thesis, the issue of distinguishing anthropogenic and climatic drivers of vegetation change was explored through the analysis of pollen, phytoliths and microcharcoal in core sediment records from Mashishing Fen in the Thaba Chweu Municipality, Mpumalanga province, northeastern South Africa, that date from ca. 11.2 – 11.7 ka BP to the present. In southern Africa, generally, the distinction between the contributions of anthropogenic and climatic factors to vegetation changes poses a complex challenge in palaeoenvironmental research. This difficulty often arises due to limited, well-dated palaeoenvironmental sequences suitable for correlations between archaeological and palaeoecological records. For the last 2000 years, there has been a scarcity of direct evidence for farming, such as grains and other domesticated plants, and pastoralism. A further difficulty is that some plant taxa may be indicators for intense droughts but also signify anthropogenic disturbances. At the centre of the thesis are three papers. The first comprises a synthesis of existing literature of archaeobotanical evidence that was done to evaluate the relationship between climate, anthropogenic activities, and vegetation change during the first millennium CE in southern Africa. I focussed on this context in the paper because it is a time in which the arrival of pastoralism and farming in the region makes it the most likely period during which distinct anthropogenic vegetation change occurred. The published data demonstrates that microfossil assemblages are potential indicators of anthropogenic activities of pre-European pastoralists and farmers of the region, with patterns including a decline in tree pollen and increases in microcharcoal, spores of coprophilous fungi, open land/disturbance indicators, and ruderal species. The second paper addresses some of the limitations of palynology as a method. A modern pollen- and phytolith-vegetation study was conducted on surface sediment samples linked to the botanical survey of five vegetation survey plots at and around Mashishing Fen to investigate the relationships between the modern pollen and phytoliths in the surface samples and the contemporary vegetation within the area. The results support the accepted view that pollen and phytoliths often do not track similar vegetation signals. The modern pollen assemblages clearly track forest and wetland vegetation, and the modern phytolith assemblages reflect grassland vegetation in the area. The study confirmed that differential phytolith and pollen production, dispersal and preservation substantially influence the proxy records and that combining phytolith and pollen data provides a more accurate basis for plant fossil interpretations in palaeoenvironmental studies. The results of this paper constrained my interpretation of the pollen data used in the third paper. Finally, pollen, spores and microcharcoal data from the core sediment records from Mashishing Fen (formerly the Lydenburg Fen) provide palaeoenvironmental records for approximately the last 11,2 to 11,7 ka years–most of the Holocene. The data is interpreted through the patterns identified in the first paper, including potential indicators of anthropogenic activities. The data of the earlier period provide a backdrop to possible anthropogenic change in the first millennium CE; the extended data illustrate paleoenvironmental changes that took place in a region occupied by hunter-gatherers but predate any possible anthropogenic influences by pastoralists or farmers. The core data suggests that the early Holocene began with moist and warm conditions that were followed by fluctuations between wet and dry conditions during the mid-Holocene and the decline of trees with the dominance of open-land indicators during the later Holocene, thereby providing the basis for correlating the palaeoecological records with the archaeological records in the region
Peat dynamics in the Angolan Highlands
(University of the Witwatersrand, Johannesburg, 2023-03) Lourenco, Mauro Cesar; Woodborne, Stephan; Fitchett, Jennifer
The Angolan Highlands is a war stricken, threatened, and under-studied area. The region is hydrologically and ecologically important and supports extensive tropical peatland deposits. Peatland preservation has been acknowledged to address climate change, is sensitive to drought and fire, and is directly influenced by vegetation and hydrological conditions. However, little research has been conducted in the Angolan Highlands. This study addresses gaps in the literature through four key contributions. The first is a critical review of peat definitions: the implications of disparate definitions are detailed, and a new proposed definition for peatlands in the interest of climate science is provided. The second is the first map of peatland extent in the Angolan Highlands, containing details on the age and growth dynamics. The study presents a conservative estimate of peatland extent that is much larger than previously estimated for Angola and is a crucial first step in facilitating the preservation of this deposit. The third contribution is the first historical assessment of drought and vegetation response in the region. This contains a 40-year drought and 20-year vegetation history, demonstrating that drought occurrence is increasing and there is a strong relationship between precipitation and the peatland vegetation region. The fourth contribution is the first assessment of the contemporary (2001-2020) fire regime of these peatlands, and reveals that among all land cover classes, peatlands burn more frequently and at a higher proportion. Investigation into the peat dynamics of the Angolan Highlands indicate that they have critical importance and are naturally resistant to both droughts and fire. Failure to preserve these deposits will have direct implications on the communities, environment, and surrounding areas.
Perspectives on the role of stakeholder engagement and participation in river basin management in South Africa: a study of the hennops river
(University of the Witwatersrand, Johannesburg, 2024) James, Lucien; Simatele, Mulala Danny
As a country that already faces hydrological and climatological challenges, South Africa’s socio-economic situation further complicates River Basin Management. This is observable through the state of rivers in the Gauteng Province such as the Hennops River. Like other rivers across the country, the state of the Hennops River is alarming, being affected by multiple sources of pollution. The state of the Hennops River Basin is observably affected by Tembisa, a poor former township area that has contributed to the pollution of the upstream Kaalspruit tributary. While the community of Tembisa contributes to the Hennops’ degradation, the potential of stakeholder engagement and community participation in Integrated River Basin Management is yet to be harnessed. The aim of this study was to investigate in what ways stakeholder and community engagement, mobilisation, as well as participation can be harnessed to promote sustainable River Basin Management considering the Hennops River Basin as a case study. The objectives of this study were to (1) analyse existing policies and frameworks which promote stakeholder engagement and community participation in River Basin Management in South Africa, (2) identify challenges and opportunities that hamper and facilitate sustainable River Basin Management through stakeholder engagement and community participation in South Africa, taking the Hennops River Basin as a case study, (3) create a sustainable model through which stakeholder engagement and community participation can be harnessed towards effective River Basin Management, and (4) Contribute to the body of knowledge on the role of stakeholder engagement and community participation in River Basin Management. Through a research design involving key stakeholders and the community, new insight was gathered about their potential through engagement and participation. Data were gathered from Key Informants, interviews, focus group discussions, as well as clean-up campaigns, which included a campaign hosted by the researcher. Findings of this study suggest that although policy supports the engagement, participation, as well as the mobilisation of stakeholders and the community, implementation thereof has been challenged. At community level, implementation is further challenged through community disinterest, a lack of support or funding for disparate initiatives, and lack of political will to address community issues. Key stakeholders, namely NGOs have taken it upon themselves to address River Basin Management. However, their initiatives are self-reliant and therefore unsustainable. Several conceptual models to address River Basin Management in South Africa are proposed. These models address (1) the implementation of policy through the establishment of effective institutions, (2) the role of the NGO in River Basin Management, (3) the funding of small projects or initiatives, (4) an approach to wicked problems in the community, and (5) the relationship between government, stakeholders, and the community. Together, these models are argued as some of the ways the potential role of stakeholder engagement and community participation can be harnessed as part of a framework for sustainable River Basin Management in South Africa. Opportunities exist to better understand stakeholder engagement and community participation, particularly in the context of leadership and agency. The framework presented as the result of this study opens the doorway to new possibilities for the implementation of policy and new approaches to water governance
Reassessing the stratigraphy and formation of the basal deposits at Klasies River Main Site with a multiscale and multiproxy approach
(University of the Witwatersrand, Johannesburg, 2024) Morrissey, Peter; Wurz, Sarah; Mentzer, Susan
The basal deposits at Klasies River Main site, associated with the MSA I and II lithic cultural phases and dating from >120 ka to ~80 ka, have yielded highly significant archaeological assemblages and human fossils across multiple phases of excavation since the late 1960s. These finds have contributed to a growing understanding of the appearance and intensification of modern human behaviours and provide rare insight into Homo sapiens anatomy during the early parts of the Late Pleistocene. The three recesses occupied during this period represent distinct depositional environments with differing degrees of attractiveness for human activities. Significant climatic, environmental, and geomorphic changes, including large fluctuations in sea level, occurred, impacting formation processes within the site complex. Stratigraphic relationships across a space like this would always be complicated but understanding them here is even more difficult because there are not continuous deposits between the recesses for all or part of their respective sequences. Geoarchaeological research has taken place alongside all three phases of excavation at Klasies. Until Sarah Wurz began her field programme in 2013, this work entailed macroscopic descriptions of standing sections (at differing resolutions) and the sedimentological analysis of bulk samples. Given the finely laminated nature of many of the deposits, even higher resolution bulk sampling resulted in the incorporation of multiple visible deposits into individual samples in many cases. More recently, archaeological micromorphology and other microscale analyses have been applied to deposits in the site complex by Susan Mentzer and colleagues. This work has provided important new insights into human behaviour and the spatially and temporally variable impacts of different diagenetic processes. Here, field observations of standing sections and microcontextual analysis are used to provide greater insight into the formation of deposits in two areas of the site complex. This information is used, along with unpublished field notes and profile drawings and critical engagement with the extensive, but seldom detailed, literature to assess and refine stratigraphic correlations of the basal deposits both between different recesses and different stratigraphic systems (the layers used in the initial excavations and the excavation units grouped into members and sub-members in subsequent work). The results demonstrate that the formation of any particular deposit could involve any number of combinations and relative intensities of different depositional and post- depositional processes. Furthermore, the interplay between geogenic, biogenic, and anthropogenic processes is often significant. Anthropogenic deposition has long been recognised as being highly significant at Klasies, but it is now also clear that humans played a major role in reworking sediment through daily activities during occupations, very likely including trampling and site maintenance activities. Chemical diagenesis had a major impact on the preservation of anthropogenic features, but variations in the intensity and frequency of anthropogenic deposition also influenced how susceptible deposits were to diagenesis. It has proven possible to correlate between the two stratigraphic systems in Cave 1B, a particularly understudied area of the site complex, providing clarity on the cultural association of a highly significant human fossil. The overall stratigraphic system used at the site complex is now also better understood, both in terms of correlations and the nature of the system. Finally, this study highlights the utility of a multiscale geoarchaeological approach to site complexes like Klasies for understanding site formation and stratigraphy. It also highlights the vital, but often ignored or underplayed, connection between site formation processes and stratigraphy, especially in such a complicated context.
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
Remote sensing-based assessment of mangrove forest changes and related regulatory frameworks for the sustainability and conservation of coastal ecosystems in Zanzibar Island, Tanzania-East Africa
(University of the Witwatersrand, Johannesburg, 2024-10) Mohamed, Mohamed Khalfan; Adam, Elhadi
Mangroves are vital components of the world's coastal ecosystems, yet they face significant threats from storm surges, tidal waves, commercial aquaculture, and expanding human settlements. These challenges have heightened the need for accurate mangrove maps to gauge ecosystem degradation. However, mapping mangroves at species and community levels is challenging due to the inaccessibility of these environments. Remote sensing offers an efficient alternative to conventional field-based methods by enabling data collection in these challenging ecosystems. This study aimed to apply remote sensing techniques to map mangrove forest changes and species in two protected bays in Zanzibar, Tanzania. The thesis focuses on four key areas. First, it examines the history of mangrove management in Zanzibar, from colonial times (1890) to the present, highlighting policies, laws, and community involvement in conservation. The colonial authority implemented several land administration laws and regulations to protect mangrove forests. However, mangrove forests suffered significant degradation from 1930 to the end of World War II. The post-independence policy framework established the legal foundation for the introduction of community involvement in mangrove conservation. The legal foundation for introducing community participation in mangrove protection was established by post-independence policy structures such as the National Forest Conservation and Management Act of 1996. Nevertheless, sustainable mangrove use remains inadequate. Second, the study compared community perceptions of mangrove ecosystem services using chi-squared tests and one-way ANOVA. Household surveys showed that provisioning services (PS) were the most identified (84%). Supporting (SS), regulating (RS), and cultural services (CS) were rated by 46.2%, 45.4%, and 21.0%, respectively. Statistical analyses indicated significant differences in the awareness of RS (χ2 = 6.061, p = 0.014) and SS (χ2 = 6.006, p = 0.014) between Chwaka, Charawe, Ukongoroni, Unguja Ukuu, and Uzi wards. There were no significant differences in the identification of PS (χ2 = 1.510, p = 0.919) and CS (χ2 = 1.601, p = 0.901). The study found that residents’ occupations did not determine their reliance on mangrove ecosystem services (χ2 = 8.015; p = 0.1554). Third, changes in mangrove cover in Menai Bay and Chwaka Bay between 1973 and 2020 were analyzed using Landsat data. TerrSet geospatial software was used to classify land cover. The SEGMENTATION module grouped pixels based on spectral similarity, and the images segments were transformed into training sites and signature classes using the SEGTRAIN module. Finally, the segments were classified with the SEGCLASS module into a pixel-based land cover map. Separation of land cover classes was determined using the Jeffries–Matusita (J-M) distance and the transformed divergence (TD) index. For Chwaka Bay, overall classification accuracy ranged from 82.5% to 92.7%, while for Menai Bay, it ranged between 85.5% and 94.5%. Producer and user accuracies ranged from 72% to 100%, with kappa coefficients (κ) between 0.72 and 0.90. Menai Bay experienced a 6.8 ha yearly decline in mangrove cover between 1973 and 2020, while Chwaka Bay saw a 48.5 ha annual decrease. Fourth, the study aimed to map mangrove species in Menai Bay using metrics extracted from the Landsat 9 OLI-2 dataset, i.e., vegetation indices (VIs) and gray-level co-occurrence matrices (GLCMs). A critical step in this study was identifying the contribution of vegetation indices and texture features to classifying mangroves. Training data from very high-resolution (VHR) unmanned aerial vehicle (UAV) data covering parts of the study area helped identify five major mangrove species, i.e., Rhizophora mucronata, Ceriops tagal, Sonneratia alba, Avicennia marina, and Bruguira gymnorrhiza. Results showed that textural features attained overall classification accuracy of 68.29% (kappa = 0.62) and 67.07% (kappa = 0.60) for random forest (RF) and support vector machine (SVM), respectively. Vegetation indices (VIs) recorded overall accuracy of 72.64% (kappa = 0.67) and 67.78% (kappa = 0.61) for RF and SVM. Overall, this study demonstrates the potential of remote sensing technologies for mapping mangrove forest changes and species in challenging environments like Zanzibar’s protected bays. By integrating historical policy analysis with modern geospatial techniques, the research highlights the significant role of both legal frameworks and community involvement in mangrove conservation. The community surveys underscore the varying perceptions of mangrove ecosystem services across different wards, with provisioning services being the most recognized. These findings underscore the importance of advancing remote sensing applications and refining conservation strategies to ensure the sustainability of mangrove ecosystems. Additionally, the analysis of long-term changes in mangrove cover from 1973 to 2020 reveals a concerning decline, particularly in Chwaka Bay. Lastly, the study’s classification of mangrove species using Landsat 9 OLI-2 data, vegetation indices, and texture metrics achieved notable accuracy, emphasizing the value of remote sensing in distinguishing species-level characteristics.
Responsible mining and sustainability in Nigeria: the case of Bitumen
(2020) Akinyosoye, Oluwole Olafusi; Wafer, Alex
The last few decades have been marked by a sense of urgency regarding the sustainable use of the earth’s natural resources. During this period, the mining and minerals industries have received particular attention in relation to their perceived destructive impact on the environment. Within this context, the discourse of responsible mining has relatively recently emerged as a possible route towards more sustainable mineral exploitation that could be the basis for sustainable development in the future. For some commentators the idea of responsible mining is an oxymoron: mineral exploitation is always environmentally too costly. For other commentators, effective management of mineral resources provides a realistic path to sustainable development for resource rich but economically poor nations. One of the key components of responsible mining is "good governance": i.e. the presence of a broadly legitimate and democratic form of governing society, which includes a balance of power in the administration of a country between the effective institutions of state and civil society. However, the past decades have suggested that there is an inherent crisis of poor governance in many developing countries, which has been identified as one of the drivers of change to initiate sustainable development. This research report offers an exploration of these two intersecting concepts of responsible mining and governance in Nigeria, in the context of the proposed economic diversification strategy through non-oil and solid minerals development. The study focusses on what might be termed the paradox of sustainable futures in Nigeria: with the proposed exploitation of bitumen reserves in a country that has a poor social and environmental reputation for oil mining. What are the prospects that bitumen could provide resources for sustainable growth in Nigeria? Despite relatively high rates of growth in the Nigerian economy in the past few years, the Nigerian economy has traditionally been overly dependent on oil and gas extraction, and the gradual decline over the past two decades has seen an overall decline in development in the country. As a result, the government has identified other resource potentials, in this context, to exploit the vast bitumen reserves in Nigeria. Whilst the idea to mine bitumen spawns the rhetoric of development in the area and huge revenues to the government for national development purposes, there is a need to explore the paradox of development from this form of mining. More importantly is the impending impact on the indigenous people, which is influenced by certain factors, especially the network of governance, to address the challenges of minerals development in Nigeria. In this context, this study is an attempt to explore the possibilities of and anxieties regarding sustainable futures in the context of the impending bitumen exploitation. The study involved 3 months of field research in Agbabu in Ondo State, Nigeria, one of the areas that will be most affected by the proposed bitumen mining. The area is largely rural, with traditional forms of land ownership and farming practices that are integral to the economic opportunities within the community. Thus, to obtain detailed knowledge of the dynamics of exploiting bitumen, this study applied a qualitative research design to conduct a case-study research on Agbabu in Ondo state, Nigeria. The review of relevant literature, focus group discussion, in-depth interviews, and key informant interviews were relevant tools that provided the data for the study. With these tools, the study gathered data from a range of respondents which included the local population, government officials and professionals who hold esteemed positions in this study concerning their experiences and opinions’ on the proposed bitumen project. The study found that despite the welcome idea of bitumen development, local mining communities still struggle with issues of being marginalised and excluded from decision-making processes in matters related to their indigenous space.
Shooting at a Moving Target: The Complexity of Evaluating and Monitoring the Adaptive Capacity to Climate Change of Local Government Institutions in South Africa: A Study of the Eastern Cape Province.
(University of the Witwatersrand, Johannesburg, 2024) Gadu, Siyaxola Ernest; Simatele, Mulala Danny
It is no longer a myth that natural catastrophic events associated with varying climate are increasing globally, with severe and devastating consequences in poor countries, particularly in Sub-Saharan Africa, where many of the world’s poor people reside. Thus, the emphasis on adapting to varying climate is no longer optional, or a deferred problem into the future, but rather an urgent matter of concern which must be considered to be a policy priority. Countering the retrogressive climate variation challenges on economic development and ecological degradation, the South African government has, in the last two and half decades, embarked on the progressive formulation of different policy instruments and strategic frameworks to curb and minimise the effects of climate variation on all economic sectors. Applying research techniques from the qualitative research approach and existing literature, this research explored the complexities of evaluating the institutional adaptive capacity to climate change in municipal institutions of South Africa, with particular focus on the Eastern Cape Province. The research outcomes indicate that, although much remains to be achieved, some level of success has been realised, particularly in the space of policy formulation, albeit with a poor record of implementation. While the policy sounds good and is solution-driven, the implementation of the programme at local levels to achieve the desired goals, however, remains a significant challenge due to institutional and capacity challenges. In addition, the research further highlighted the fragmented climate change governance system which has posed significant systemic challenges, and these have tended to constrain decision-making and implementation processes. The institutional and capacity challenges create an unconducive environment for adequate coping strategies, and an evaluation of institutional adaptive capacity at municipal level across the country. The study findings also stressed the prominence of indigenous knowledge, and the alliance between the opportunities presented by climate variation and Sustainable Development Goals. This study further emphasized the importance of developing a reliable system to assess and monitor the institutional coping capacity at municipal level that can compare adaptive capacity of different institutions and assist in resource allocation
Social vulnerability in the adaptation of rural communities to climate change in Imo State, Nigeria
(University of the Witwatersrand, Johannesburg, 2024) Okoro, Franklin Chimaobi; Knight, Jasper
Rural communities in developing countries such as Nigeria are faced with frequent extreme weather/climate events that impact their economy, health, and environment due to the combination of high social vulnerabilities, low social resilience, and low adaptive capacities. The aim of this study is to investigate the root causes of social vulnerability in rural communities in Nigeria and how rural households use their social capital and networks to adapt to the impacts of climate change. The study used ten (10) social vulnerability indicators (factors) to ascertain their influence on social resilience and adaptive capacity during climate related disasters. To achieve this purpose, three communities in Imo State, Southern Nigeria were selected, and distributed 240 structured questionnaires to rural household heads, interviewed 18 local stakeholders and climate change actors (government agencies), and conducted three (3) Focus Group Discussions (FGDs) with group of farmers from the three selected communities. The questionnaire survey, interview, and FGD guides contained open-ended questions that allowed participants to report freely. The quantitative data derived from the questionnaire survey were subjected to descriptive analysis using SPSS while the qualitative data were subjected to thematic analysis to derive relevant themes for discussions. The result of the study shows that social vulnerability is a function of age, gender, education, household size, income, sources of livelihood, disability, means of transport, access to healthcare, and alternative accommodation being available during climate emergencies. The study further shows that social vulnerability of rural residents was exacerbated by societal vulnerability influenced by political, economic, cultural, and social factors. Although there are other weather/climate extreme events (disasters), however, the most prominent is floods, constituting 48.3% of the weather/climate events experienced in the study area with its impacts requiring more efficient climate adaptation strategies other than the traditional measures like relocation/migration, use of early maturing crop varieties, early planting and harvesting. However, rural households drew support from government, NGOs, and oil companies but the help from family members, friends, neighbours, social group members (social networks) were more beneficial and helped more rural residents to improve their social resilience. The study recommends that rural residents be encouraged to join social groups since their memberships in such groups will help to improve their social resilience, and that government and its agencies should engage multi-stakeholders in their genuine efforts to develop more effective measures for climate change adaptation.