Research Articles (Geology)
http://hdl.handle.net/2263/1738
2024-03-29T12:11:27ZEnhancing hydrological analysis by incorporating environmental and artificial tracers of an altered vadose zone : a systematic review
http://hdl.handle.net/2263/95337
Enhancing hydrological analysis by incorporating environmental and artificial tracers of an altered vadose zone : a systematic review
Van Wyk, Yazeed; Dippenaar, Matthys Alois; Ubomba-Jaswa, Eunice
This review investigates the integration of environmental and artificial tracers for evaluating water flow within modified vadose zone environments and assesses how heterogeneous structures and preferential flow influence transport mechanisms, residence times, and flow pathways. Utilising both single and multiple tracers the precision of flux estimations between the vadose zone and water table can be enhanced. Altered vadose zones substantially influence tracer storage and release based on shifting moisture levels, highlighting the hydrological importance of these altered zones. The review underscores the importance of high-frequency measurements for diverse hydrological systems and understanding contaminant transport processes, with vadose zone thickness influencing residence times and hydrological behaviour and enhancing groundwater protection. Insights into the study of karst aquifers using fluorescent dyes and natural tracers shed light on rapid flow dynamics, and how to improve modelling techniques to capture these complexities. This further highlights the need to address safety and regulatory considerations related to tracer use, particularly toxicity and ecotoxicity effects, which are critical when borehole water is utilised for domestic purposes. In this regard, the development of a standardised regulatory framework in South Africa, given the absence of specific tracer test guidelines, drawing from international examples should be established. Numerical models for vadose zone flow and contaminant transport tackle challenges like non-equilibrium processes, complex geometries, and heterogeneity. Methods like Picard and Newton iterations can therefore enhance model accuracy, vital for sustainable water resource management and understanding modified vadose zone processes.
DATA AVAILABILITY : No data was used for the research described in the article.
2024-04-01T00:00:00ZThe progression of disclosures in the basic materials industry of South Africa
http://hdl.handle.net/2263/95267
The progression of disclosures in the basic materials industry of South Africa
Du Toit, Elda; Delport, Pieter Willem Jacobus
Considering debates surrounding the usefulness of integrated reporting for decision-making, this exploratory study uses objective measures to investigate the quality of disclosures other than financial in the basic materials industry of South Africa. Annual and integrated reports for the basic materials and consumer discretionary industries are evaluated over 12 years, from 2008 to 2020 for a total of 1204 firm-year observations to investigate whether (1) integrated reporting brought positive change and (2) whether reporting improved over time. Readability and narrative tone analyses are conducted, and non-parametric Kruskal-Wallis tests are used to investigate the development of these measures over time. The results show that corporate reports in the basic materials industry decreased in quality over time in that the reports have become longer, less readable, and use specific narrative tones, which can create biases. The findings reveal that the declining quality of reports in the basic materials industry could mislead or deter investors, challenge regulatory oversight, and ultimately, impact firms' social licence to operate. Thus, they offer actionable insights for firms to improve disclosure by reducing complexity and length and adopting a neutral narrative tone to mitigate biases, thereby making these reports more accessible and useful for a wider stakeholder audience. In addition, investors ought to demand better reporting, and regulators should tighten guidelines.
DATA S1: Supporting Information.
2024-03-01T00:00:00ZProbabilistic tsunami risk assessment from incomplete and uncertain historical impact records : Mediterranean and connected seas
http://hdl.handle.net/2263/94170
Probabilistic tsunami risk assessment from incomplete and uncertain historical impact records : Mediterranean and connected seas
Triantafyllou, Ι.; Papadopoulos, G.A.; Kijko, Andrzej
Tsunami risk is considered as the probability of a particular coastline being struck by a tsunami that may cause a certain level of impact (destructiveness). The impact metric of a tsunami is expressed in terms of tsunami intensity values, K, assigned on a 12-degree scale. To calculate tsunami risk we are based on the tsunami history of the region codified in tsunami catalogues. The probabilistic model adopted was used successfully for hazard assessment of earthquakes (Kijko et al. in Bull Seismol Soc Am 79:645–654, 2016) and of tsunamis (Smit et al. in Environmetrics 30:e2566, 2019) by considering seismic magnitude and tsunami height as metrics of the respective hazards. In this model, instead of hazard metrics we inserted risk metric, i.e. wave impact in terms of intensity values. The procedure allows utilization of the entire data set consisting not only from the complete (recent) part of tsunami catalogue but also from the highly incomplete and uncertain historical part of the catalogue. Risk is assessed in terms of probabilities of exceedance and return periods of certain intensity values in specific time frames. We applied the model using catalogues for the Mediterranean and connected seas. Sensitivity analysis showed that using complete data sets generally provided more realistic results than using entire data sets. Results indicated that the risk level depends on the seismicity level and not on the size of individual ocean basin. The highest tsunami risk level was found in the eastern Mediterranean (EM), with a significantly lower risk in the western Mediterranean (WM). In the Marmara Sea (MS), the tsunami risk was low, and the lowest was in the Black Sea (BS). The risk in the small Corinth Gulf (CG, Central Greece) was comparable to that of WM. The return period of damaging tsunamis (i.e. K ≥ 7) was 22 years in the entire Mediterranean basin and 31, 118, 135, 424, and 1660 years in the EM, WM, CG, MS, and BS basins, respectively.
DATA AVAILABILITY : The data sets used in this paper and the relevant citations are explained in the main text and summarized in Supplementary file 1.
2023-03-01T00:00:00ZFirst-order approximation towards empirical seismic vulnerability assessment of low-cost unreinforced masonry buildings in South Africa
http://hdl.handle.net/2263/93997
First-order approximation towards empirical seismic vulnerability assessment of low-cost unreinforced masonry buildings in South Africa
Nqasha, Thando; Khoyratty, Zeenat; Akombelwa, Mulemwa; Singh, Mayshree; Kijko, Andrzej
The 5 August 2014 Orkney earthquake in South Africa caused significant damage to low-cost unreinforced masonry buildings. After the earthquake, post-earthquake surveys were conducted to assess damage and deduce the intensity experienced by these buildings. During these surveys, only buildings that were reported as damaged were investigated. This study conducted an empirical seismic vulnerability assessment using data collected from those surveys. However, for a comprehensive assessment, the data should include all buildings in the study area. Hence in this study, a first-order approximation was applied to gather sufficient data to construct fragility curves for low-cost unreinforced masonry buildings in South Africa. The damage probability matrix technique was used for fragility curve construction. The fragility curves were constructed using the intensity and damage data, statistical models, and model fitting techniques. The fragility curves obtained in this study predicted comparable but slightly lower damage compared to other curves for unreinforced masonry buildings of similar typology. Although the method applied was able to produce fragility curves comparable with other studies, it is recommended that in order to get a reliable fragility curves all the buildings in the study area should be investigated including those that suffered little to no damage.
DATA AVAILABILITY STATEMENT : The datasets generated during and/or analysed during the current study can be available from the corresponding author on reasonable request upon agreement with the institution.
2024-01-01T00:00:00Z