4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item The geopolitics of climate change and violent conflicts in Africa: the Nigerian and Kenyan perspectives(University of the Witwatersrand, Johannesburg, 2024) Emupenne, Olanrewaju Ojo; Small, MichelleThis study empirically examined the correlation between climate change (independent variable) and violent conflict (dependent variable), focusing on East Africa and West Africa. Climate change poses a serious threat to humanity and the ecosystem, particularly in Africa. Also, despite other serious challenges the continent faces, violent conflict remains among the most devastating. Various reasons, including poor leadership, social exclusion, and conflicting goals, are cited as causes of violent conflict in Africa. Recently, a new narrative has emerged suggesting climate change is a potential driver of violent conflicts. This study examines the correlation. So, to investigate this relationship, a survey research design was employed. The study adopted a descriptive research design, and four main research methods were used in the study namely, mixed methods research, comparative case study research, triangulation approach to social research, and convergent synthesis design. Also, the research utilized questionnaires that were directly formulated from the study’s hypotheses and were tested using a parametric regression model. Furthermore, the research employed Key Informant Interviews (KII), and the data gathered were processed using Atlas.ti, a Computer Assisted Qualitative Data Software (CAQDAS). Sampling techniques included purposive, stratified, and random sampling. The study population comprised government officials, environmentalists, academia, farmers, herders, youth leaders, and community leaders. 17 government officials, 7 academia, 6 environmentalists, 15 farmers, and 13 herders randomly selected in Nigeria, and 22 government officials, academia, and environmentalists, 15 farmers and members of farmers cooperatives, and 12 herders and members of livestock associations randomly selected in Kenya participated in the Key Informant Interviews (KIIs) to make a sample size of 110. In addition, 174 government officials, environmentalists, and academics completed the Set A questionnaire in Nigeria, 116 government officials, environmentalists, and academics completed the Set A questionnaire in Kenya, and 423 farmers, herders, youths, and community leaders completed the Set B questionnaire in Nigeria, and 205 respondents do the same in Kenya to make a sample of 918 respondents. In all, a total of 1,028 respondents participated in the study. The study was systematically guided by four research questions and two hypotheses. These research questions are as follows: (1) To what extent does climate change effect features in the geopolitics of peace and security in West Africa and East Africa? (2) Specifically, what is the correlation between climate change and farmer-herder conflicts in the Middle Belt region of Nigeria and farmer-herder conflicts in the Tana River County in Kenya? (3) What is the level of awareness about the effects of climate change among crop farmers, herders, and policymakers in the Northern region of Nigeria and Tana River County of Kenya, and how does the knowledge about the effects of climate change play a role in the different stakeholders’ approach to conflict? (4) What are the policy frameworks in Nigeria and Kenya that create awareness about climate change and mitigate the effects vi of climate change on violent conflict at both national and local levels? The quantitative data obtained were analyzed using SPSS Version 25 and R, while the qualitative data were analyzed using Atlas.ti. Results revealed a positive correlation between climate change and geopolitical dynamics of peace and security in West Africa and East Africa but did not establish causation. While climate change intensified, it contributed to shifts in geopolitical dynamics impacting peace and security. However, establishing causation requires more than observing correlation; it demands demonstrating that changes in the independent variable cause changes in the dependent variable. The findings of the study also revealed varying levels of knowledge and awareness regarding climate change among farmers, herders, and policymakers in Northern Nigeria and Tana River County of Kenya; divergent opinions about available policy frameworks for creating awareness about climate change and mitigating the effects of climate change on violent conflict. Some of the respondents agreed that policies were available, some were of the view that policies were available but not implemented while some expressed the fact that policies were not available. Considering these findings, several policy recommendations were made which include the integration of climate adaptation strategies with conflict prevention efforts, decision- making and policy implementation, creating more awareness programmes, indigenous approach and inclusivity, curbing migration, farmer/herder dialogue, and the establishment of special judicial commission solely for farmers and herders. In a nutshell, the study emphasized the need for nuanced understanding and consideration of multiple factors influencing the geopolitical landscape of AfricaItem Assessing how an alternative waste management system may facilitate subaltern and environmental justice: a thematic analysis of a zero waste pilot case study in South Africa(University of the Witwatersrand, Johannesburg, 2024) Van Biljon (née Swart), Johanna Yvonne (Jani)Waste is socio-political – a symbol of our economic and consumerist society. Since the Industrial Revolution, our manufacturing processes and materialist lifestyles produced more hazardous and nondegradable externalities than we were prepared to deal with. With environmental and consumer pressure building, we are at a crossroads between continuing with business-as-usual and justly transitioning over to a systemically different, zero waste society where the focus on waste management shifts to waste prevention so that, like Karl Marx, it challenges and eventually changes production processes, ownership, consumption, and ultimately, our connection with the natural environment and each other. South Africa’s waste landscape is characterised by two things: its reliance on landfills and the thousands of informal waste pickers reclaiming the value of discarded goods. So, what could a zero waste system that is just toward the environment and the subaltern look like in South Africa? In exploring this question, I considered the work of waste pickers, as well as the case of an urban composting initiative for an inner-city market supporting the zero waste philosophy. Synthesising these, I imagine a gradual, deep bottom-up transformation in attitude, behaviour and eventually infrastructure with regard to our relationship with the environment, ownership and use, as well as the revaluation of the material and therefore waste ‘management’. The role and insights of waste pickers and local, informal economies will be crucial and influential. Though South African waste pickers do not yet participate in the organic waste stream on a noticeable scale, the prioritisation of composting by the Warwick Zero Waste project and the National Waste Management Strategy sees the recovery and local, low-tech, low-cost composting of organic waste as a vital starting point in establishing a more regenerative food and waste system that will build solidItem Framing of climate change in South Africa: An analysis of content in News24 and TikTok(University of the Witwatersrand, Johannesburg, 2024) Mawila, Cathrine; Sithole, EnockClimate change has become a danger to the planet and human survival. This has incited dialogs about the subject to gain momentum on international economic and political platforms. The discussion about climate science and climate change is mainly conducted in the mainstream media and the internet. However, the internet, as a communication channel, is fast taking over the role of traditional media as a platform for distributing information to the public. The internet has opened up new avenues for public debates and has allowed the public to discuss important issues such as climate change. In South Africa, many researchers employed the content analysis media theory to study different frames on news media coverage of climate change. Previous studies analysed tweets and blogs in South Africa on the subject of climate change and argued that although there was some closeness in the way print media and online media covered topics on climate change, online media had become the most frequently used to interact and reach audiences effectively and in real-time. This study took the matter forward and compared the framing of climate change in two distinct platforms, News24 and TikTok, between April 2022 and April 2023 to understand the topic across diverse sections of media users in South Africa. The study found that News24's framing of climate change was mostly linked to weather events or climate disasters, while TikTok's engagement with the issue was found to be inadequate. The study also found that misinformation was prevalent in TikTok. Furthermore, News24's articles were influenced by international narratives, while TikTok's frames were based on rudimentary knowledge. The most prevalent frames in both News24 and TikTok were socio-economic and disaster-related, likely due to the recent KZN floods. The study also found that TikTok lacks reputable sources. The findings of this study could prove useful in guiding climate change communicators to focus on educating the general public about climate change, given the prevalence of climate change misinformation on social media platformsItem The impact of climate change on the performance of banks in Southern Africa(University of the Witwatersrand, Johannesburg, 2023) Ralebona, Phumudzo; Gwatidzo, TendaiUsing a sample of 12 countries from the SADC region, the study investigates the impact of climate change on the performance of commercial banks. The study this paper uses temperature and rainfall levels to measure climate change. Secondary data gathered through extraction of historical databases obtained from World Bank Development Indicators is used to deduce the relationship of these variables. The results suggest that climate change matters. The study finds that although there is a positive relationship between bank profitability and climate change, there is a threshold beyond which further increases in temperature and rainfall will adversely affect bank profitability. Also, banking sector concentration has a positive effect on banking profitability, while loan loss provisions and costs can erode profits if not managed properly. We also discover that there is no difference in how South Africa is affected by climate change compared to the rest of the SADC countries. A number of policy recommendations emanate from the study. First, it imperative for banks to begin to take into account climate change in the operational activities. Second, there is no country immune from the ravages of climate change. All countries in the SADC region must cooperate to address the serious challenges emanating from climate change. For example, the impact of climate for South African banks is not different to the banking sectors in other countries in the SADC region. Indeed, across most countries in the region natural disasters, such as droughts and floods, are becoming more frequent and also more devastating. Third, to address some of the challenges there is need to address the problems of, data scarcity and to use technology innovation to prevent natural disasters. These recommendations will equip the SADC region to be able to tackle the anticipated consequences of climate change on the financial institutionsItem Hydroponic farming for saffron cultivation in South Africa(University of the Witwatersrand, Johannesburg, 2024) Smit, JohanIn South Africa, saffron has exclusively been cultivated using traditional farming methods. Although farmers face an increasing range of challenges and uncertainties, hydroponic farming offers an opportunity to alleviate many of these challenges, while simultaneously increasing output and reducing input expenses. The primary objective of the planned business venture was to investigate the possibility for hydroponic saffron farming in South Africa. The study focused on the development of a hydroponic system to cultivate saffron, aiming to mitigate the daily difficulties and risks faced by conventional farmers. The study adopted a qualitative exploratory research approach. The study gathered substantial information through interviews with farmers in both the traditional saffron and non-saffron hydroponic industries. Interviewing farmers provided insights into the perspectives of persons involved in both the traditional saffron industry and the non-saffron hydroponic growing sector. Three hydroponic cultivators and one saffron farmer were interviewed face-face. Another Saffron farmer was interviewed telephonically. The study examined the necessary requirements for hydroponic saffron cultivation in South Africa, covering technical factors for saffron cultivation, operational prerequisites, financials, market analysis, and challenges. The research findings highlighted the significance of hydroponic systems within an overall context. The main driving force for the transition from traditional farming to hydroponics was climate change among the participants. An essential challenge in hydroponic saffron growing is its relatively lower profitability compared to other crops like herbs, lettuce, and tomatoes. Including the concept of opportunity cost into the breakeven analysis will lead to a reduced repayment period, hence justifying the concept of saffron cultivation with a hydroponic system. In conclusion, cultivating saffron with hydroponics is a sustainable solution when considering opportunity costs due to the value of the spice, and the increasing uncertainty of climate change affecting output.Item Responsiveness of South African semi-commercial farmers to climate change(University of the Witwatersrand, Johannesburg, 2024) Maliba, Bheki; Saruchera, FannyAgriculture is crucial for sustaining rural livelihoods and promoting economic growth. However, climate change threatens agriculture as it is directly linked to climate factors. This study assesses how semi-commercial farmers are responding to climate change. The objectives were to (1) examine the perceptions of South Africa’s semi-commercial farmers on climate change; (2) assess the responsiveness of semi-commercial farmers to climate change; and (3) assess the influence of adaptation strategies on the performance of semi-commercial farmers. The data was collected through a self-administered questionnaire from 90 respondents and analysed. The demographic characteristics of the semi-commercial farmers were analysed using frequencies and descriptive statistics. In addition, a correlation analysis was conducted to determine relationships between different constructs, and multiple linear regression was used to model the relationship between variables. Most of the 90 respondents were 35 to 54 years old and had a high level of tertiary education (83.33%). The analysis of years in farming reveals a moderate experience level among participants, with 56.67% engaged in farming for 10-24 years. Rainfed agricultural practices dominated, with 57.78% relying solely on natural rainfall. Regarding access to credit, the mean score of 2.21 (standard deviation = 1.06) shows that, on average, respondents disagreed with the statements in the questionnaire about access to adequate credit, affordable lending rates, easy access to finance and alternative funding sources. Crop productivity indicated a positive correlation with soil and water conservation, and there was a positive correlation between changes in temperature and soil and water conservation. This suggests that their perception of temperature changes influences semi-commercial farmers' adaption strategies and that adopting climate strategies improves crop productivity. The study proved that soil and water conservation and crop diversification significantly predict crop productivity (performance). Recognising the positive correlation between soil and water conservation and crop diversification techniques and the perceived increased crop productivity, policymakers and agricultural extension services should prioritise and advocate for these strategies. Given the significant variations in respondents' access to credit, interventions should be tailored to the different financial needs of semi- commercial farmers. It is recommended that future research incorporate more comprehensive analyses of the development prospects of semi-commercial farmers, considering regional differences and assessing the long-term impact of adaptation strategies on actual agricultural productionItem A documentation of the morphology of the lungs of the Sprague Dawley rat after chronic heat exposure(University of the Witwatersrand, Johannesburg, 2023) Peya, Yolanda; Reddy, DeranClimate change is a natural phenomenon that is exacerbated by mul4ple human ac4vi4es in the environment. These ac4vi4es lead to a rise in global temperatures. This increases the occurrence of heatwaves which pose a major threat to ecosystems, biodiversity, and the conserva4on of species on Earth. This study, aimed to document the effects of chronic heat exposure on the lungs of the Sprague Dawley rat using histological and immunofluorescence techniques. Twenty-four (24) rats were assigned to three groups; each exposed to different temperatures; (i) group A (n = 8) exposed to 25 °C (ii) group B (n = 8) exposed to 33 °C and (iii) group C (n = 8) exposed to 34 °C. This was done for a period of 4 weeks and the rats were euthanised therea`er. Methods employed included Intratracheal instillation, and histological and immunofluorescence techniques. This study found that rats in group A (25 °C) displayed no structural adapta4ons in comparison to groups B and C. Enlarged blood vessels with thick smooth muscle and prominent elas4c fibres, bronchus-associated lymphoid 4ssue (BALT), and increased collagen deposi4on were observed in group B (33 °C). These indicate the ac4va4on of immune responses and adapta4on to new environmental temperatures. In group C (34 °C), the lung morphology was severely damaged. There was an increased loss of epithelial integrity, oedema, pulmonary alveolar proteinosis (PAP), and a severe decrease in the lung- to-surface area ra4o. The significant changes caused by the 1 °C temperature difference between groups B (33 °C) and C (34 °C) illustrate the detrimental effects of chronic heat stress. It is evident that increasing environmental temperatures due to climate change is harmful to life and immediate interven4ons are necessary to combat rising temperaturesItem Symmetry reductions and approximate solutions for heat transfer in slabs and extended surfaces(University of the Witwatersrand, Johannesburg, 2023-06) Nkwanazana, Daniel Mpho; Moitsheki, Raseelo JoelIn this study we analyse heat transfer models prescribed by reaction-diffusion equations. The focus and interest throughout the work is on models for heat transfer in solid slabs (hot bodies) and extended surface. Different phenomena of interest are heat transfer in slabs and through fins of different shapes and profiles. Furthermore, thermal conductivity and heat transfer coefficients are temperature dependent. As a result, the energy balance equations that are produced are nonlinear. Using the theory of Lie symmetry analysis of differential equations, we endeavor to construct exact solutions for these nonlinear models. We will employ a number of symmetry techniques such as the classical Lie point symmetry methods, the nonclassical symmetry, nonlocal and nonclassical potential symmetry approach to construct the group-invariant solutions. In order to identify the forms of the heat source term that appear in the considered equation for which the principal Lie algebra (PLA) is extended by one element, we first perform preliminary group classification of the transient state problem. Also, we consider the direct group classification method. Invariant solutions are constructed after some reductions have been performed. One-dimensional Differential Transform Method (1D DTM) will be used when it is impossible to determine an exact solution. The 1D DTM has been benchmarked using some exact solutions. To solve the transient/unsteady problem, we use the two-dimensional Differential Transform Method (2D DTM). Effects of parameters appearing in the equations on the temperature distribution will be studied.Item The application of machine learning methods to satellite data for the management of invasive water hyacinth(University of the Witwatersrand, Johannesburg, 2023-06) Singh, Geethe; Reynolds, Chevonne; Byrne, Marcus; Rosman, BenjaminBiological invasions are responsible for some of the most devastating impacts on the world’s ecosystems, with freshwater ecosystems among the worst affected. Invasions threaten not only freshwater biodiversity, but also the provision of ecosystem services. Tackling the impact of invasive aquatic alien plant (IAAP) species in freshwater systems is an ongoing challenge. In the case of water hyacinth (Pontederia crassipes, previously Eichhorniae crassipes), the worst IAAP presents a long-standing management challenge that requires detailed and frequently updated information on its distribution, the context that influences its occurrence, and a systematic way to identify effective biocontrol release events. This is particularly urgent in South Africa, where freshwater resources are scarce and under increasing pressure. This research employs recent advances in machine learning (ML), remote sensing, and cloud computing to improve the chances of successful water hyacinth management. This is achieved by (i) mapping the occurrence of water hyacinth across a large extent, (ii) identifying the factors that are likely driving the occurrence of the weed at multiple scales, from a waterbody level to a national extent, and (iii) finally identifying periods for effective biocontrol release. Consequently, the capacity of these tools demonstrates their potential to facilitate wide-scale, consistent, automated, pre-emptive, data-driven, and evidence-based decision making for managing water hyacinth. The first chapter is a general introduction to the research problem and research questions. In the second chapter, the research combines a novel image thresholding method for water detection with an unsupervised method for aquatic vegetation detection and a supervised random forest model in a hierarchical way to localise and discriminate water hyacinth from other IAAP’s at a national extent. The value of this work is marked by the comparison of the user (87%) and producer accuracy (93%) of the introduced method with previous small-scale studies. As part of this chapter, the results also show the sensor-agnostic and temporally consistent capability of the introduced hierarchical approach to monitor water and aquatic vegetation using Sentinel-2 and Landsat-8 for long periods (from 2013 - present). Lastly, this work demonstrates encouraging results when using a Deep Neural Network (DNN) to directly detect aquatic vegetation and circumvents the need for accurate water extent data. The two chapters that follow (Chapter 3 and 4 described below) introduce an application each that build off the South African water hyacinth distribution and aquatic vegetation time series (derived in Chapter 2). The third chapter uses a species distribution model (SDM) that links climatic, socio-economic, ecological, and hydrological conditions to the presence/absence of water hyacinth throughout South Africa at a waterbody level. Thereafter, explainable AI (xAI) methods (specifically SHapley Additive exPlanations or SHAP) are applied to better understand the factors that are likely driving the occurrence of water hyacinth. The analyses of 82 variables (of 140 considered) show that the most common group of drivers primarily associated with the occurrence of water hyacinth in South Africa are climatically related (41.4%). This is followed by natural land cover categories (32.9%) and socio-economic variables (10.7%), which include artificial land-cover. The two least influential groups are hydrological variables (10.4%) including water seasonality, runoff, and flood risk, and ecological variables (4.7%) including riparian soil conditions and interspecies competition. These results suggest the importance of considering landscape context when prioritising the type (mechanical, biological, chemical, or integrated) of weed management to use. To enable the prioritisation of suitable biocontrol release dates, the fourth chapter forecasts 70-day open water proportion post-release as a reward for effective biocontrol. This enabled the simulation of the effect of synthetic biocontrol release events under a multiarmed bandit framework for the identification of two effective biocontrol release periods (late spring/early summer (mid-November) and late summer (late February to mid-March)). The latter release period was estimated to result in an 8-27% higher average open-water cover post-release compared to actual biocontrol release events during the study period (May 2018 - July 2020). Hartbeespoort Dam, South Africa, is considered as a case study for improving the pre-existing management strategy used during the biocontrol of water hyacinth. The novel frameworks introduced in this work go a long way in advancing IAAP species management in the age of both ongoing drives towards the adoption of artificial intelligence and sustainability for a better future. It goes beyond (i) traditional small-scale and infrequent mapping, (ii) standard SDMs, to now include the benefits of spatially explicit model explainability, and (iii) introduces a semi-automated and widely applicable method to explore potential biocontrol release events. The direct benefit of this work, or indirect benefits from derivative work outweighs both the low production costs or equivalent field and lab work. To improve the adoption of modern ML and Earth Observation (EO) tools for invasive species management, some of the developed tools are publicly accessible. In addition, a human-AI symbiosis that combines strengths and compensates for weaknesses is strongly recommended. For each application, directions are provided for future research based on the drawbacks and limitations of the introduced systems. These future efforts will likely increase the adoption of EO-derived products by water managers and improve the reliability of these products.Item Assessing aquifer vulnerability to landfill pollution using drastic method in Gauteng, South Africa(University of the Witwatersrand, Johannesburg, 2023) Mphaphuli, Idah; Abiye, TamiruThis study integrated the DRASTIC method and field investigations into mapping the degree of vulnerability of aquifers to landfill pollution in the Gauteng Province, which is one of the most populated provinces in South Africa. In order to investigate the aquifer vulnerability of Gauteng's heterogeneous and complex geology, the DRASTIC method was used to generate intrinsic and specific vulnerability maps. Three vulnerability classes were generated from the DRASTIC index, namely, low vulnerability, moderate vulnerability and high vulnerability, which covered 46%, 37% and 17% of the study area, respectively. The highly-vulnerable areas were associated with the karst aquifer of Malmani dolomite, permeable vadose zone, high hydraulic conductivity and loamy sand/sandy loam soil type, whilst moderately-vulnerable areas were associated with fractured/weathered aquifers, high recharge and low topography. The intrinsic vulnerability was validated using average NO3+NO2-N (nitrate + nitrite as nitrogen) and the results of water samples from field investigations conducted in Marie Louise and Robinson landfill sites. Elevated NO3+NO2-N concentration (9.85-16.03 mg/l) was observed in the highly-vulnerable areas. Water samples were collected, in order to analyse the water chemistry, stable isotopes and radioactive isotopes (tritium). Gibbs and Piper diagrams were used to evaluate the main mechanism controlling the groundwater chemistry and the dominant major ions that influence it. Pollution by leachate was detected in the Marie Louise landfill site, where the groundwater showed high tritium and ammonia concentration. The main hydrochemical facies detected in Marie Louise were Mg SO4, Ca-SO4, Na-SO4 and Na-Cl. The hydrochemical facies detected in Robinson were Na-SO4, Ca-HCO3, Na-Cl and Ca-Cl. The DRASTIC method was shown to be effective in assessing groundwater vulnerability on a regional scale, provided that there is adequate input data.