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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Modification of gradient winds by dissected topography in the vicinity of the Jonkershoek Valley

Ngeleza, Eric B January 1993 (has links)
Includes bibliography. / The pilot balloon runs and synoptic charts show that mountain and valley winds at the Jonkershoek valley correspond with the west to east ridging of anticyclones over the South Western Cape. Saddles between the South Atlantic and South Indian anticyclones are particularly conducive to the development of well established local wind circulations at Jonkershoek. Gradient winds during the occurrence of saddles are shown to be light and variable. Deep gradient southeasterlies undergo an acceleration to the lee of the ridges resulting in strong airflow at the Jonkershoek valley bottom. The topography at Jonkershoek is shown not have any meaningful modifying effect on the gradient northwesterlies.
192

Climatic trends and soil moisture feedbacks over Zimbabwe

Mdoka, Marshall Lison January 2005 (has links)
Includes bibliographical references (leaves 106-118). / The research focuses on an objective analysis of austral summer rainfall variability over Zimbabwe as well as characterization of rainfall patterns and frequency analysis over southern Africa region. A statistical analysis of historical trends in climate extreme events is used and lays a foundation of projecting into future climates. A trend analysis done on rainfall patterns attained from SOMs approach compliments the RClimdex statistical approach and strengthens some of the historical trends findings on climate extremes. Thereafter, some exploratory research seeks to explain the trends observed using the land-atmosphere interactions and shows the response of rainfall to anomalous soil moisture conditions during an extreme wet and dry seasons using RegCM3. Finally, some radiation effects results are presented from these soil moisture perturbations experiments. Results show drying out patterns over the region from the historical records analysed. The trend analysis done with SOM arrays revealed a positive trend towards drier conditions and a negative trend for wet conditions. The climate extremes indices analysis complimented these findings as shown in the decrease in total precipitation and an increase in the number of dry spells. This is supported by the circulation patterns showing an increase in frequency of the 500hPa anticyclones and a decrease of low pressures. However, some high altitude stations showed an intensification of precipitation events. This would exacerbate need for proper planning of future water resource management and farming strategies. Soil moisture rainfall feedback mechanisms were not fully explored. However drier conditions experiments showed a stronger response to soil moisture perturbations than in wetter conditions experiments. No consistent response to soil moisture initialisation over southern Africa was found. The altitude does modulate these feedback mechanisms with low-lying areas depicting a stronger response. A better understanding of the observed rainfall patterns, historical climate trends and soil moisture-rainfall feedback mechanisms are essential for improved short-term and seasonal forecasting and will aid the generation of plausible climate change impact predictions.
193

Urban-scale material flow analysis in a South African context: a Cape Town feasibility study

Hoekman, Paul January 2015 (has links)
Urban-scale Material Flow Analyses (MFAs) in the global south provide unique challenges compared to national MFAs and to urban MFAs in the north. In order to determine the feasibility of undertaking an urban-scale MFA in the global south, this dissertation sets out to undertake an MFA on Cape Town, and thoroughly analyze the data collection process, document the challenges, and interpret data quantity and quality. Data were found for nearly all flows defined in the Eurostat methodology, but only for the most recent of three consecutive years under study. Data quality is challenged by high variance in reliability of sources, difficulty in obtaining documents, additional work required to process the data, lack of data on informal or illegal flows, and the scattered distribution of sources. Data collection took 345 hours during a period of 22 weeks and involved interaction with a total of 325 contacts and 86 documents. The principal activities were related to contacting and interacting with people. Most time was spent on e-mailing and meeting people, and significant time was furthermore spent on transportation to and from meetings. Not all time was spent effectively and efficiently. Chasing unreliable data and unproductive cross-checking were the principal culprits. Despite the challenges, the quantity and quality of data are of a sufficient level to provide interesting insights into the urban metabolism for Cape Town, and undertaking this kind of urban-scale MFA is thus deemed feasible. Once a time-consuming, initial MFA has identified valuable and reliable sources, periodic repetition should be relatively uncomplicated. Through government involvement or industry cooperation, data collection and data sharing with a few key stakeholders can make regular urban MFA reporting a feasible reality. This work shows who those key stakeholders are and how researchers and government can undertake and improve future urban MFA studies - not only on Cape Town but also on other regions and cities in South Africa. This MFA feasibility study furthermore provided useful insight into the metabolism of Cape Town. For 2013, local extraction was 1.53 t per capita, mostly consisting of non-metallic minerals mined within the borders of Cape Town. Wild fish catch is half of the biomass extraction. Imports and exports were 4.04 t and 2.15 t per capita, respectively, with food and fossil fuels weighing heavily on the imports. The exports are dominated by processed foods and products from the manufacturing industry. Emissions to air can be contrasted with the results from Gasson (2007). Significant per-capita emission increases are seen for CO2 , coupled with decreases for most other emissions to air. Compared to other Eurostat-based urban studies on cities in Western Europe, Cape Town resource flows are significantly lower on a per-capita basis.
194

Late quaternary environmental reconstruction and climate modelling in the winter rainfall region of the Western Cape, South Africa

Mulock-Houwer, Anne January 2001 (has links)
Bibliography: leaves 124-144. / The southwestern Cape of South Africa is a floristically diverse region experiencing winter rainfall, and is important as it represents a significant southern hemisphere example of a Mediterranean climate regime. Acquiring palaeoenvironmental data from this region is imperative in understanding the climatic changes that have occurred during the Late Quaternary, with a view to improved palaeclimatic modelling. The spatial distribution of studies for the Late Quternary in the southwestern Cape is uneven and palaeoenvironmental reconstructions have been largely restricted to sites, which are easilty accessible, and appropriate only for the methods being used (e.g. palynology for wetlands). Moreover, many of the palaeoenvironmental reconstructions implemented thus far fall outside the winter rainfall region sensu stricto. Hence spatial differentiation in climatic response may have remained obscured due to the 'selection' of sites used.
195

A spatial analysis of the Alternative Admissions' Research Project at the University of Cape Town, 2000 - 2005.

Takalani, Takadzani January 2012 (has links)
Includes bibliographical references. / The purpose of this dissertation is to demonstrate the potential contribution of spatial analysis using GIS on candidates who undergo the Alternative Admissions Research Project (AARP) tests for alternative admission to University of Cape Town (UCT). Spatial analysis may be useful in interrogating existing information on the geographical distribution of AARP candidates, in particular, those who are regarded as educationally disadvantaged as a result of apartheid policy and practices of the past. GIS techniques and tools were applied in order to assess accessibility of UCT AARP services provided to students nationally, and to demonstrate how GIS may be incorporated into the various academic faculties at UCT, particularly academic faculty recruitment planning.
196

Stakeholder involvement in the development of genetically modified (GM) food labelling policy in South Africa

De Beer, Taryn Lynne January 2015 (has links)
Like many other countries worldwide, South Africa has come under public pressure to introduce mandatory GM labelling. Although there is an increased understanding about the social and political implications of GM labelling in developed countries, there is still a research gap with regard to implications for developing countries. South Africa, as a country that consumes, produces and trades GM food, represents a fitting case study to investigate these dimensions in the context of a developing economy. There has been very little understanding about how the mandatory labelling law for GM food developed in South Africa. This study, thus, aims to analyse how this policy developed and has been implemented in South Africa, in order to draw wider conclusions about GM food labelling in developing countries. This has been achieved through review of the relevant literature, in-depth interviews with 27 stakeholders from industry, government, NGOs and the academic and scientific community, and document analysis. A stakeholder analysis approach was used for framing and informing the research findings of this study. This framework provided a stakeholder perspective through which to examine the policy development process of mandatory GM labelling. Findings from this research project reveal that the policy governing the mandatory labelling of GM foods in South Africa was developed and shaped by many significant events and decisions. However, the law evolved within a context of conflict from a diversity of stakeholders. Stakeholders, who participated in and contributed towards the process, had their own degree of "interest and power", which influenced and impacted on the GM labelling policy-making and the implementation processes. Research revealed that there were important issues that emerged during the policy development and implementation phases. These included: the effectiveness of stakeholder participation; the use of a "may contain" label; the percentage of the threshold level; and labelling costs. The stakeholders' viewpoints on each of these issues differed among different groups.
197

Heavy metal contamination in the Black River, Cape Town

Gilbert, Lucy Jane January 2015 (has links)
Urban river sediments are often contaminated as a result of development and anthropocentric activity, and the Black River in Cape Town is a prime example of a river system suffering from unsustainable development. Methods of deter mining total and background concentrations of selected heavy metals were researched and utilized in the effort to quantify heavy metal concentrations derived from anthropogenic sources in the Black River . The findings were intended for use in the aim of producing sediment quality guidelines (SQG) for South Africa as described in the Water Research Commission Phase I Report; Developing Sediment Quality Guide lines (Gordon and Muller, 2010). The ability of the invasive Eichhornia crassipes (water hyacinth) to uptake and store heavy metals was also briefly investigated to identify its potential as a phyto - remediator in the Black River. Toxicity of the sediment was quantified using the consensus - based mechanistic approach (Gordon & Muller, 2010) whereby assuming that total concentration of a heavy metal is the critical factor in its hazardousness. Sediment samples were divided into grain size and measured by X - Ray Fluorescence and concentrations of the focus elements antimony, arsenic, cadmium, chromium, copper, nickel, lead, and zinc in the mud fraction were compared with Consensus Based Sediment Quality Guidelines (McDonald et al., 2002). Based on guide line exceedances, the most toxic sample was collected from anoxic sediment conditions at the point where the N2 Highway crosses the Black River. The succeeding high toxic ity risk locations were all within areas slightly downstream of a river convergence or within 50 m of one, specifically the Vygekraal, Jakkelsvlei, Esliekraal and Kromboom rivers. Exceedances were most common for chromium, copper, lead, nickel and zinc. The least toxic sample was collected 160 m downstream of the Athlone wastewater treatment works, with the one sample collected between these two points also holding relatively low toxicity risk. Concentrations of the selected analytes were also compared to results from a previous study conducted in 2002 on the Black River sediment (Haniff). The comparison suggested contamination has generally worsened in the past 13 years however due to potentially large analytical error from the differences in sample analyses in 2002 and in this investigation; the reliability of the comparative study is limited to general observation. The data implies that the Athlone wastewater treatment works was contributing to heavy metal concentrations in the sediment in 2002, but now in 2015 appears to improve sediment quality. The Water Research Commission Phase I report identifies four ways to assess sediment quality to produce SQG; one of which is to establish normal background concentrations. In this investigation, background concentrations of heavy metals from natural sediment input to the Black River was estimated using two methods, the first was by combining globally recognized average shale values (Turekian and Wedepohl, 1961; USGS, 2000) with results obtained from studies undertaken on virgin soils of the Black River catchment area (Soderberg, 2003; Herselman, 2007) to form what is referred to as Estimated Background Values (EBV). The second method was to measure element concentrations of weakly - acid rinsed and milled coarse grain fraction of the Black River sediments. This was to see whether concentrations of the coarse fraction reflect those of the EBV, and to establish whether this would be a feasible method of estimating background concentrations which takes into account the multiple inputs of natual sediment across the river catchment. It was concluded from the application of the t - test that the coarse grain fraction held similar concentrations to 19 major and trace elements of the EBV with 95% certainty, and were comparable for all the focus elements accept antimony and arsenic. The mud fraction heavy metal concentrations were then applied to three statistical indicators; the Pollution Load Index (PLI), the Geo - accumulation Index (I - Geo) and the Enrichment Factor (EF) in the objective to quantify anthropogenic input using both the EBV and coarse grain fraction results as reference values. All statistical indicators suggest the river is most enriched with cadmium, copper, lead and zinc, which most likely derive from roadside deposit/stormwater drainage and industries. The application of EBV to the statistical indicators revealed relatively little pollution enrichment, whereas the coarse grain results suggested much higher leve ls of pollution enrichment in the Black River. This disparity verifies the importance in selecting/obtaining suitable data sets as screening values for investigating heavy metal enrichment (Gałuszka & Migaszewski, 2012). It was concluded that the coarse grain fraction element concentrations would not be feasible for use as EBV in the case of the Black River. This is due to the large assumptions made whilst using this method, namely that the coarse grain fraction is assumed to derive from the same source as the mud fraction. Due to the known disturbances to natural sedimentation in the Black River, it is doubtful that the fractions come from the same source. Also given the relatively low heavy metal concentration in the coarse grain fraction, it is likely that the majority of the sand in the sediment of the Black River derives from the coastline. Heavy metal concentrations in the water hyacinth and sediments were applied to the Bio - accumulation Factor to identify the potential of the species as a phyto - remediating agent in the Black River. All four water hyacinth samples contained high concentrations of cadmium, and high concentrations of arsenic, nickel and antimony in three samples. Mercury was present (albeit at low concentrations) in three out of the four plant samples, yet was not detected in any of the 32 sediment samples, supporting the conclusions of Buta et al (2011) that the plant has a very strong affiliation to mercury, and that the element has a high affinity to bind with dissolved organic carbon and suspended sediment. The Bio - accumulation Factor revealed the phyto - remediation potential of the water hyacinth is high for antimony, arsenic, cadmium, mercury, lead and nickel. Water hyacinth could therefore be utilized more effectively (with the use of controlled growth) to remediate sediments indirectly by removing heavy metals from the water and preventing them settling into the sediment. Short - term fluctuations in heavy metal presence and kinetic components cannot be conservatively evaluated due to sediment disturbances, complexities within river system inputs and the ever changing environmental conditions. The findings are based on equilibrium status and the conditions at the time of sampling, and are limited to confinements of the reliability of data generated from sample collection, preparation methods and sample analysis. The distribution of metals in sediments of the Black River if not controlled by dredging is generally controlled by the association of heavy metals with very fine grained, organic - rich sediment. In addition, locations of high element enrichment reflect other river inputs which drain from various areas of the Cape Flats, with the most significant being the Esliekraal convergence. Conclusions from the investigation suggest the method of establishing background concentration from the coarse grain fraction could be applicable only to urban rivers which have seen few sedimentation disturbances and are relatively isolated from externa l sources away the local catchment. This method could reduce sampling costs and be used along with the application of other means available mentioned in the Water Research Commission Phase I report to create South African sediment quality guidelines.
198

Development of benchmarks and weighting systems for building environmental assessment methods : opportunities of a participatory approach

Kaatz, Ewelina January 2001 (has links)
Bibliography: leaves 41-44. / Sustainable construction is a tenns that emerged with the introduction of the concept of sustainable development in construction. Therefore, sustainable construction embraces socio-economic, cultural, biophysical, technical and process-orientated aspects of construction practice and activities. The progress towards sustain ability in construction may be assessed by implementation of good practice in building developments. Therefore, building environmental assessment methods are valuable tools of indicating such a progress as well as promoting sustainable approaches in construction. An effective building environmental assessment method requires definition of explicit benchmarks and weightings. These should take into account environmental, social and economic contexts of building developments. As the existing building environmental assessment methods largely ignore socioeconomic impacts of building developments, the implementation of a participatory approach in the development of benchmarks and weighting systems could greatly contribute to a more meaningful incorporation of social and economic aspects into the assessment process. Furthennore, the participation of stakeholders in establishing qualitative benchmarks and weights should increase the credibility of such a process. The participatory approach could allow for education of all stakeholders about the potential environmental, social and economic consequences of their decisions and actions, which is so vital for achieving their commitment to strive towards sustainable construction.
199

The valuation of beaches as urban open space

Mitchell, S S January 2001 (has links)
Bibliography: leaves 23-24. / The beach is a unique open space in the urban context. It is a dynamic aggressive environment that has in the past been ignored as an open space that has special qualities. While it has been seen purely as a recreational facility, ecosystem services and intrinsic values have been ignored. In Cape Town planning guidelines now set store on the value of open space, however the fear is that there may be insufficient emphasis on the beach as an urban edge and an open space element. While ecosystem service can and have been calculated intrinsic values present some difficulties.
200

An investigation into dry and wet spell characteristics over Zambia and into the onset of the rainy season

Hachigonta, Sepo Promise January 2005 (has links)
Includes bibliographical references (leaves 113-124). / Recurring dry/wet spells and decreased agricultural productivity during the last decade in the southern and northern parts of Zambia point to the need for a clearer understanding of these events, their frequencies and their possible connection to large-scale climate modes. Apart from having a high number of dry spells during the December-February (DJF) core rainy season, the southern part of Zambia is frequently subjected to late onset dates and short durations of the rainy season whereas the northern and northwestern region frequently have high numbers of wet spells which in most cases lead to flooding. Using CMAP and station data, rainfall variability in terms of dry spells, wet spells, onset and cessation dates of the Zambian rainy season and the associated circulation anomalies are investigated. The study also looks at relationship between these extreme events with Nin03.4 SST anomalies. Low level easterly anomalies over Zambia are enhanced during seasons with high dry spells. As a result, there is reduced moisture penetration into Zambia from the Angola low and reduced low level moisture convergence over the country and hence increased dry spells. During the seasons with high numbers of wet spells, there are low level westerly anomalies over southern Angola and western Zambia implying a strong moisture influx from the tropical South East Atlantic and increased convergence over Zambia. It was shown that El Nino (La Nina) events typically result in above (below) average DJF dry spell frequency in Zambia. Early onset dates over the northern parts of Zambia were observed to occur during strong El Nino seasons and the strength of the observed relationship with Nin03.4 SSTs seems to be stronger for years during the 1980s than those during the 1990s. Early onset dates tend to occur for years with higher than average dry spell frequency in the following DJF season. This suggests that early onset may be a disadvantage in that it often leads to more dry spells during the subsequent peak growing period of the season.

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