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Now showing 1 - 5 of 19

Recent Submissions

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    Markov chain monte carlo methods vs. variational inference approaches in posterior density estimation for bayesian neural networks
    (University of the Witwatersrand, Johannesburg, 2025-12) Chabumba, Daisy Reneilwe; Mlambo, Farai; Chironda, Cyril
    Not Available
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    A comprehensive environmental assessment of the Braamfontein Spruit and surrounding tributaries in Northern Johannesburg in 2023 and 2024
    (University of the Witwatersrand, Johannesburg, 2025-04) Butler, Dylan; Dahms-Verster, Simone; Sheridan, Craig
    Urban environments are complex systems comprising of interconnected systems consisting of built-up areas, gardens, parks and rivers. These ecosystems provide essential services that support climate resilience, yet urban developments places them under stress, reducing their ability to perform such services. The Braamfontein Spruit in Johannesburg, South Africa, illustrates how urbanisation impacts river health and ecosystem services. This study aimed to assess the spatiotemporal variation in water quality across multiple sites along the Braamfontein Spruit catchment and tributaries, to evaluate the influence of human activity on river health. Sampling was conducted at five sites during three seven-week periods between April 2023 and March 2024. Sites included the two tributaries (Westdene Spruit and Montgomery Spruit0, the Parkview Golf Course, Delta Park, and the Sandton Riverclub Golf Course. Field measurements were taken using a Merck multivariate probe, while biodiversity was assessed using the SASS5 method. Water and sediment samples were collected and analysed for nutrients (sulphate, nitrite, nitrate, phosphate), microbial indicators (E. coli and coliforms), and metals (Fe, Pb, Mn) using standard laboratory methods. Results revealed variable but consistently concerning contamination across sites and seasons. Nutrient and microbial concentrations frequently exceeded South African Department of Water and Sanitation guidelines, with particularly high E. coli and coliform levels at sites along the Braamfontein Spruit. SASS5 biomonitoring scores were low, indicating degraded ecosystems, and negative correlations were served between nutrient and microbial levels and macroinvertebrate richness. These findings highlight the cumulative impacts of urban pollution in Johannesburg’s rivers and underscore the urgent need for improved water quality management in areas of high recreational and domestic use.
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    Using machine learning to identify the spatial extent of acid mine drainage from gold mining activities in Gauteng, South Africa
    (University of the Witwatersrand, Johannesburg, 2025) Bullah, Nikita; Mahboob, Muhammad Ahsan; Atif, Iqra
    Acid mine drainage (AMD) poses a significant environmental and public health risk, particularly in mining-intensive regions. This study examines the spatial extent of AMD contamination in the Bloubankspruit and Crocodile River systems in Gauteng, South Africa, by analysing heavy metal concentrations in surface soils along a 20 km stretch downstream of the abandoned Kromdraai gold mine. Soil samples were collected at six locations at 4 km intervals and analysed using X-ray fluorescence (XRF) spectroscopy. The results indicate that AMD contamination is most severe within the first 4 km, with sulphur concentrations reaching 6 911 mg/kg, exceeding the acceptable threshold of 4 000 mg/kg by 72,8%. Cobalt levels were elevated across all sample sites, with the highest recorded concentration at 49.2 mg/kg—over eight times the permissible limit of 6 mg/kg. Chromium and copper concentrations also surpassed regulatory standards at 40,6 mg/kg and 32,6 mg/kg, respectively. A statistical analysis of variance (ANOVA) confirmed significant variation in contamination levels across sites (F = 30,23, p < 0,05), with AMD pollutants decreasing exponentially downstream due to natural dilution and sedimentation processes. The study further demonstrates that the gentle topographical gradient (0,0097) of the region limits surface runoff, constraining AMD migration beyond the immediate vicinity of the mine. The findings emphasize the urgent need for targeted remediation efforts, such as bioremediation and passive treatment systems, to mitigate the long-term environmental impact of AMD. This research provides critical insights into the transport dynamics of mining-related pollutants and supports the development of more effective water quality management strategies in affected river systems.
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    Examining Factors Influencing the Adoption of e-HRM in the South African Public Sector: An Integrated Diffusion of Innovation (DOI) Theory and Trust Perspective
    (University of the Witwatersrand, Johannesburg, 2019) Phiri, Mxolisi Abednego; Bancilhon, Jean-Marie
    The increase in the use of technology by organizations to transform the Human Resource Management (HRM) function to be more strategic has changed the way employees interrelate and perceive the HRM. For instance, the implementation of technological innovations in human resources has gradually replaced the old traditional face-to-face, manual, and paper-based interactions between employees and their respective HRM personnel. These technological innovations include the use of real-time web-based HRM portals or applications, also known as, the electronic human resource management (e-HRM) to facilitate the employer-employee HRM processes. Furthermore, successful implementation of e-HRM has potential benefits of elevating the value of human resource function (Grant & Newell, 2013) to be that of a strategic business partner (Bondarouk, Schilling & Ruël, 2016), thus reducing time the HR function spends on administrative tasks. However, the diffusion of these technological innovations (e-HRM) into HRM practices and the realization of its potential benefits will depend on whether the employees of a firm are willing to adopt and optimally utilize the technology. It is for this reason that this study was undertaken. The purpose of this study is to investigate the determinants of e-HRM adoption in the South African public sector. Additionally, this study draws on the Diffusion of Innovation Theory (DOI) and contemporary literature on user trust in technology to develop and test a theoretical model of the factors influencing the South African public sector employees’ adoption of e-HRM. Moreover, this study took a positivist approach and an online survey method was used to obtain the empirical data. The empirical data was collected from a sample of 173 employees of the Road Accident Fund (RAF), a state-owned entity. The results show that there is an overall adoption of e-HRM amongst the RAF employees. Correlation analysis showed that the RAF employees perceived relative advantage, compatibility, complexity, observability, voluntariness, and trust to have a significant direct effect on e-HRM adoption. Additionally, the results showed that trialability had a significant impact on e-HRM adoption on its own but not in the presence of the aforesaid independent variables. In closing, this study serves as a guide for examining factors contributing to e-HRM adoption. In addition, it affords the public sector decision makers with Examining Factors Influencing the Adoption of e-HRM in the South African Public Sector: An Integrated Diffusion of Innovation (DOI) Theory and Trust Perspective
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    Exploring diversity in executive positions among JSE-Listed companies
    (University of the Witwatersrand, Johannesburg, 2025) Chibi, Nicholus Loyd; Gobind, Jenika
    This research examined gender and racial diversity among executives who lead companies that are listed on the Johannesburg stock Exchange [JSE]. The executive leadership positions in South African companies show low representation of women and historically disadvantaged racial groups despite the country's progressive legislative framework that includes the Employment Equity Act [EEA] and the Broad-Based Black Economic Empowerment [B- BBEE] Act. The research evaluated executive diversity levels while identifying organisational barriers to progress and assessing current policies and organisational strategies. The research employed qualitative methods through senior executive interviews from different sectors while analysing corporate reports that are publicly available. The research based its findings on Social Identity Theory and Agency Theory to understand how identity and bias and governance structures affect diversity results. The study showed that organisations understand diversity's value better, yet they face ongoing challenges from unconscious bias and insufficient leadership development programs and inconsistent transformation policy execution. The research suggests that organisations should implement specific leadership development programs together with enhanced accountability systems and organisational cultural changes toward inclusive leadership approaches. The research adds to South African corporate transformation discussions while offering practical solutions to enhance executive leadership diversity and inclusion.