Sediment connectivity in the upper Thina Catchment, Eastern Cape, South Africa
- Authors: Van der Waal, Benjamin Cornelis Wentsel
- Date: 2015
- Subjects: Soil erosion -- South Africa -- Eastern Cape , Sedimentation and deposition -- South Africa -- Eastern Cape , Watersheds -- South Africa -- Eastern Cape , Arroyos -- South Africa -- Eastern Cape , Sediment transport -- South Africa -- Eastern Cape , Soil conservation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4892 , http://hdl.handle.net/10962/d1019754
- Description: [Portion of abstract]: Sediment dynamics are influenced by transformed landscape connectivity in catchments worldwide. The upper Thina catchment, an important high rainfall resource in the northern Eastern Cape, South Africa, is an example of where ongoing subsistence farming on communal land has led to overgrazing and trampling that has initiated large erosive features (e.g. gullies) and river incision. The formation of gullies led to increased hillslope-channel connectivity and the resultant river incision decreased the channel-valley fill connectivity. These two changes in connectivity led to increased sediment export from the catchment that has various down-stream ecological and socio-economic impacts. This study investigates how the change in hillslope-channel and channel-valley fill connectivity has altered the sediment dynamics in the Vuvu catchment, a headwater tributary of the Thina River. A combination of methods were used to assess the changes in hillslope-channel and channel-valley fill connectivity. High resolution aerial images were used to map source features, such as fields, gullies, sheet erosion, landslides, roads and livestock tracks. Topographic and geological characteristics of the source features were extracted using a Geographic Information System. Furthermore, hillslope-channel pathways, such as the natural drainage network, continuous gullies, discontinuous gullies, roads and livestock tracks were mapped and analysed in terms of topographic and geological characteristics. Historic aerial images were assessed to calculate the date the larger gullies began forming. Recent aerial photos and cross sectional surveys of the valley fill were combined to map the various sediment sinks. Particle size and organic content were analysed for flood bench cores and terrace samples. The chronology of the flood benches was determined using unsupported Pb-210 and Cs-137 dating, and determined for the terraces using Optically Stimulated Luminescence dating. Quantitative and qualitative sediment tracing approaches, using mineral magnetic properties, were used to trace the origin of suspended sediment (collected during flood events), sediment stored in the flood benches and sediment stored in the terraces. Hydrological monitoring was used to assess the potential to store sediment on flood benches along the valley fill through flood bench inundation frequency. Hydrological and hydraulic modelling extended the measured inundation frequencies to a 73 year period and other cross sections along the valley fill. Furthermore, a future scenario of an increased vegetation cover and reduced hillslope-channel connectivity was assessed in terms of channel-valley fill inundation frequency.
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Determining the competency of children with developmental delays to testify in criminal trials
- Authors: Van Niekerk, Hester Aletta
- Date: 2015
- Subjects: Child witnesses -- South Africa , Developmentally disabled children -- South Africa , Children -- Legal status, laws, etc. -- South Africa , Evidence (Law) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3722 , http://hdl.handle.net/10962/d1017878
- Description: In South Africa children are required to testify under oath or admonition. The shortcomings of the competency test are of particular relevance to children with developmental disabilities, since courts are not equipped to adequately assess the competency of these children to give evidence. One component of testimonial competency, namely the understanding of the concepts truth and lies, is overemphasised and is examined with questions that are developmentally inappropriate for child witnesses in general. For children with cognitive disabilities, such questions create barriers for participation in the truth-seeking process. Consequently, convictions have been set aside on appeal owing to procedural irregularities found in the implementation of this test. In the literature review on testimonial competency, attention was given to restrictions that specific developmental disabilities impose on the perceptual, cognitive, communication and moral development of children. Two of four components – narrative ability and moral capacity – were studied in a sample of 184 children in middle childhood. Participants’ ability to give coherent and detailed accounts of events, their understanding of the concepts truth, lies, promises and the oath, and the Lyon and Saywitz oath-taking competency test, were investigated. Quantitative and qualitative methods were used for data analysis. Three groups were identified: those children with very limited, average or full testimonial competency. Their capacities were found to be related to maturation of cognitive functions and level of intellectual functioning. Participants were better able to demonstrate their understanding of truth and falsity by responding to the oathtaking test than giving verbal descriptions of these concepts. Whereas 1 percent of participants had a conceptual understanding of an oath, 15 percent understood the concept of a promise. Syncretism and confabulation compromised the narrative accounts of a substantial number of participants. Syncretism relates to immature narrative ability: correct details are combined in an illogical fashion. Confabulation refers to filling memory gaps with fabricated information. Guidelines on the competency determination of children with developmental disabilities were compiled. It is suggested that the competency examination be replaced by a formal, pre-trial competency assessment. The court should also receive expert evidence on how to facilitate meaningful participation when a child with sufficient testimonial competence is the witness.
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The use of hydrological information to improve flood management-integrated hydrological modelling of the Zambezi River basin
- Authors: Vilanculos, Agostinho Chuquelane Fadulo
- Date: 2015
- Subjects: Hydrologic models -- Zambezi River Watershed , Watershed management -- Zambezi River Watershed , Water resources development -- Zambezi River Watershed , Flood control -- Zambezi River Watershed , Flood forecasting -- Zambezi River Watershed , Rain gauges -- Zambezi River Watershed
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6054 , http://hdl.handle.net/10962/d1018915
- Description: The recent high profile flooding events – that have occurred in many parts of the world – have drawn attention to the need for new and improved methods for water resources assessment, water management and the modelling of large-scale flooding events. In the case of the Zambezi Basin, a review of the 2000 and 2001 floods identified the need for tools to enable hydrologists to assess and predict daily stream flow and identify the areas that are likely to be affected by flooding. As a way to address the problem, a methodology was set up to derive catchment soil moisture statistics from Earth Observation (EO) data and to study the improvements brought about by an assimilation of this information into hydrological models for improving reservoir management in a data scarce environment. Rainfall data were obtained from the FEWSNet Web site and computed by the National Oceanic and Atmospheric Administration Climatic Prediction Center (NOAA/CPC). These datasets were processed and used to monitor rainfall variability and subsequently fed into a hydrological model to predict the daily flows for the Zambezi River Basin. The hydrological model used was the Geospatial Stream Flow Model (GeoSFM), developed by the United States Geological Survey (USGS). GeoSFM is a spatially semi-distributed physically-based hydrological model, parameterised using spatially distributed topographic data, soil characteristics and land cover data sets available globally from both Remote Sensing and in situ sources. The Satellite rainfall data were validated against data from twenty (20) rainfall gauges located on the Lower Zambezi. However, at several rain gauge stations (especially those with complex topography, which tended to experience high rainfall spatial variability), there was no direct correlation between the satellite estimates and the ground data as recorded in daily time steps. The model was calibrated for seven gauging stations. The calibrated model performed quite well at seven selected locations (R2=0.66 to 0.90, CE=0.51 to 0.88, RSR=0.35 to 0.69, PBIAS=−4.5 to 7.5). The observed data were obtained from the National Water Agencies of the riparian countries. After GeoSFM calibration, the model generated an integration of the flows into a reservoir and hydropower model to optimise the operation of Kariba and Cahora Bassa dams. The Kariba and Cahora Bassa dams were selected because this study considers these two dams as the major infrastructures for controlling and alleviating floods in the Zambezi River Basin. Other dams (such as the Kafue and Itezhi-Thezi) were recognised in terms of their importance but including them was beyond the scope of this study because of financial and time constraints. The licence of the reservoir model was limited to one year for the same reason. The reservoir model used was the MIKE BASIN, a professional engineering software package and quasi-steady-state mass balance modelling tool for integrated river basin and management, developed by the Denmark Hydraulic Institute (DHI) in 2003. The model was parameterised by the geometry of the reservoir basin (level, area, volume relationships) and by the discharge-level (Q-h) relationship of the dam spillways. The integrated modelling system simulated the daily flow variation for all Zambezi River sub-basins between 1998 and 2008 and validated between 2009 and 2011. The resulting streamflows have been expressed in terms of hydrograph comparisons between simulated and observed flow values at the four gauging stations located downstream of Cahora Bassa dam. The integrated model performed well, between observed and forecast streamflows, at four selected gauging stations (R2=0.53 to 0.90, CE=0.50 to 0.80, RSR=0.49 to 0.69, PBIAS=−2.10 to 4.8). From the results of integrated modelling, it was observed that both Kariba and Cahora Bassa are currently being operated based on the maximum rule curve and both remain focused on maximising hydropower production and ensuring dam safety rather than other potential influences by the Zambezi River (such as flood control downstream – where the communities are located – and environmental issues). In addition, the flood mapping analysis demonstrated that the Cahora Bassa dam plays an important part in flood mitigation downstream of the dams. In the absence of optimisation of flow releases from both the Kariba and Cahora Bassa dams, in additional to the contribution of any other tributaries located downstream of the dams, the impact of flooding can be severe. As such, this study has developed new approaches for flood monitoring downstream of the Zambezi Basin, through the application of an integrated modelling system. The modelling system consists of: predicting daily streamflow (using the calibrated GeoSFM), then feeding the predicted streamflow into MIKE BASIN (for checking the operating rules) and to optimise the releases. Therefore, before releases are made, the flood maps can be used as a decision-making tool to both assess the impact of each level of release downstream and to identify the communities likely to be affected by the flood – this ensures that the necessary warnings can be issued before flooding occurs. Finally an integrated flood management tool was proposed – to host the results produced by the integrated system – which would then be accessible for assessment by the different users. These results were expressed in terms of water level (m). Four discharge-level (Q-h) relationships were developed for converting the simulated flow into water level at four selected sites downstream of Cahora Bassa dam – namely: Cahora Bassa dam site, Tete (E-320), Caia (E-291) and Marromeu (E-285). However, the uncertainties in these predictions suggested that improved monitoring systems may be achieved if data access at appropriate scale and quality was improved.
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Wolfgang Koeppens auseinandersetzung mit der tradition: aspekte der intertextualität in der so genannten nachkriegs‐trilogie
- Authors: Weber, Undine S
- Date: 2015
- Subjects: Koeppen, Wolfgang, 1906-1996 -- Criticism and interpretation , Koeppen, Wolfgang, 1906-1996 -- Works -- 1986 , German fiction -- 20th century -- History and criticism
- Language: German
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3658 , http://hdl.handle.net/10962/d1020833
- Description: Wolfgang Koeppen’s three post‐war novels have often been called a trilogy, purely based on their publication in rapid succession in the early 1950s. This study establishes a connection between the works by looking at their roots in Irish, Anglo‐American, French and German modernism, and shows up links between Wolfgang Koeppen, James Joyce, E.E. Cummings, Charles Baudelaire and Thomas Mann. This comparative analysis concludes, by integrating socio‐political factors of life in West Germany after World War II, that Koeppen transcends the modernist tradition – the fact that modernism has become tradition, i.e. it has become “classic”, in contradiction to being “modern”. Koeppen’s texts do not only allude to and build on classic texts and refer to stylistic and narrative modernist elements such as stream‐of‐consciousness and sketching a fragmented society in turmoil; the very act of recurring to myths and texts of the Western canon in order to depict the disaffected individual is an almost post‐modern one.
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Friend or foe? : Resolving the status of the submerged macrophyte Myriophyllum spicatum L. (Haloragaceae) in southern Africa
- Authors: Weyl, Philip Sebastian Richard
- Date: 2015
- Subjects: Eurasian watermilfoil -- Africa, Southern , Eurasian watermilfoil -- Biological control
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5933 , http://hdl.handle.net/10962/d1017811
- Description: Myriophyllum spicatum L. (Haloragaceae), a submerged macrophyte, has been recorded in southern Africa since 1829, but only considered problematic as recently as 2005. In light of this, water resource managers are looking to control M. spicatum in southern African water bodies where it is problematic. Amongst control options available in South Africa, biological control is potentially the most cost effective and sustainable option for M. spicatum. However, there is a debate over the status of this plant in southern Africa with several authors reporting it as a native component of the aquatic ecosystem, while others argue that it has been introduced from Europe or Asia. The aim of this thesis is to use a multifaceted approach to resolve the status of M. spicatum, by studying aspects of its history, distribution, mechanisms of its adaptations, biotic interactions and genetic relationships in southern Africa. By resolving the status of this plant as either native or exotic, appropriate management strategies can be initiated for its control in situations where it is considered a problem.A review of the evidence collected from this thesis does not provide convincing evidence for the anthropogenic introduction of M. spicatum into southern Africa, and it is probably native to the region. The disjunct distribution as well as regular local extinctions of populations is relatively common for species that are at the edge of their range. The populations in southern Africa could thus be relics from a much wider distribution in the past. The development of local adaptations in southern Africa provides evidence for this and suggests that the populations have been isolated for a substantial period of time and have had a long evolutionary history in the region. The lack of specialist herbivores should suggest that M. spicatum has been introduced, but the complete lack of herbivores, including generalists, may weaken that argument. The lack of herbivores could be a result of something inherent in the plant, irrespective of a lack of evolutionary history in the region. The genetic evidence suggests a European origin, but is characteristic of a population (southern Africa as a whole) that has been isolated for a considerable time. Despite the findings of this research, M. spicatum is considered problematic in southern Africa and warrants control in certain systems. Whether or not biological control should be a component of the management strategy is open to further debate. The benefits in a southern African context may outweigh the risks, based on the specificity of the biological control agent proposed. However, the perceived negative impacts of M. spicatum are likely to be a symptom of a more serious underlying cause, such as nutrient loading and changes in land use patterns. Therefore the control of this native species is a water resource management issue and not a biological control issue.
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Molecular systematics and biology of two closely related blowflies : Lucilia sericata and Lucilia cuprina
- Authors: Williams, Kirstin Alexa
- Date: 2015
- Subjects: Lucilia sericata , Lucilia cuprina
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5934 , http://hdl.handle.net/10962/d1017812
- Description: The greenbottle blowflies, Lucilia sericata (Meigen, 1826) and Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) are very difficult to distinguish on the basis of their external morphology. The literature suggests that these two species may be interbreeding. Sequencing two nuclear (28S rRNA and Period) and one mitochondrial (COI) gene indicated that there has been an ancient hybridization event and that mtDNA of L. sericata has become fixed in a lineage of L. cuprina through mtDNA introgression, possibly involving Wolbachia infection. This has implications for identifications of these species based on mtDNA alone. No study has shown explicitly that hybrids of L. sericata and L. cuprina can be identified morphologically. Morphological characters used to identify L. sericata and L. cuprina were scored and tested using specimens of both species and known hybrids. Discriminant function analysis of the characters successfully separated the specimens into three unambiguous groups – L. sericata, L. cuprina and hybrids. This is the first evidence that hybrids of these two species can be identified from physical characteristics.Lucilia sericata and L. cuprina have medical, veterinary and forensic importance. Knowing their distribution in South Africa would allow more effective management and utilisation of these flies. Their predicted geographic distributions in South Africa were modelled using maximum entropy analysis of selected climatic variables. The most important environmental variables in modelling their distributions were magnitude of monthly rainfall and the magnitude of the monthly maximum temperature for L. sericata, and the seasonal variation in monthly mean humidity and magnitude of monthly rainfall for L. cuprina. Both species have a widespread distribution in South Africa and one therefore cannot identify specimens of these flies by locality of capture alone.Luciliinae is a diverse and geographically widespread subfamily containing four genera - Hemipyrellia, Lucilia, Dyscritomyia and Hypopygiopsis – that all contain parasitic species ranging from saprophages to obligate parasites. The phylogenetic relationships between these genera are unclear. The 28S rRNA, COI and Period genes of 14 species of Lucilia and Hemipyrellia were partially sequenced and analysed together with 11sequences from GenBank and the Barcode of Life Database (BOLD). Lucilia sericata and L. cuprina were shown to be sister-species. Three cases of paraphylly were identified within Lucilia that affects identification of these species using mtDNA alone. Hemipyrellia consistently caused Lucilia to be paraphyletic when it was included in analyses, so Hemipyrellia should be synonymized with Lucilia. The relationships of Dyscritomyia and Hypopygiopsis to Lucilia are unclear and further studies are required. No geographic pattern was found within the different forms of parasitism within this group, but the different degrees of parasitism were phylogenetically clustered.
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Neurocognitive effects of head and body collisions on club level rugby union players
- Authors: Zoccola, Diana
- Date: 2015
- Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3257 , http://hdl.handle.net/10962/d1016397
- Description: The objective of the study was to investigate the cumulative neurocognitive effects of repetitive concussive and subconcussive events in club level Rugby Union (hereafter rugby) during the course of one rugby season, in a combined group and individualized case-based approach. Amateur adult club level rugby players (n = 20) were compared with a non-contact control group (n = 22) of equivalent age, years of education and estimated IQ (p = > .05, in all instances), although the two groups were clearly differentiated on the basis of a history of reported concussions (p = < .05). Video analyses documented the tackling maneuvers observed amongst the players during all matches across the rugby season revealing a sobering average of more than a thousand tackles per player, excluding any contact practice sessions. Five rugby players (n = 5) who were observed to have a head jarring event were also isolated for individualized postconcussive follow-up analysis of their neurocognitive profiles. Measures included the ImPACT Verbal and Visual Memory, Visual Motor Speed and Reaction Time composites and the Purdue Pegboard. Independent and dependent statistical analyses were employed to compare the rugby versus control group neurocognitive test profiles at and between the three test intervals. Correlational analyses explored the association between concussion, tackling and neurocognitive test outcomes. Descriptive comparisons of individual neurocognitive test scores with normative data were employed for the case analyses. Taken together, the results implicated vulnerability amongst club rugby players on the motor and speeded tasks, with less robust indications on the memory tasks. While limited in terms of its small sample size, it is considered that the outcome of the study was rendered more robust by virtue of being methodologically multifaceted with heuristic implications for future research studies in the area. The novel inclusion of tackling data as well as fine-tuned case analyses, were of particular relevance in that regard. The results add to a growing body of literature that implicates deleterious neurocognitive effects in participants of a sport such as rugby due to repetitive head jarring incidents that are intrinsic to the game.
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