Nature conservation, protected areas and local communities : the Tsitsikamma National Park
- Authors: Le Fleur, Yvette Adele
- Date: 2021-04
- Subjects: National parks and reserves -- South Africa -- Eastern Cape , Protected areas -- Management , Programme of Work on Protected Areas , Human ecology -- South Africa -- Tsitsikamma , Nature conservation -- Citizen participation
- Language: English
- Type: thesis , text , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/177247 , vital:42803
- Description: Since the twentieth century, protected areas, usually in the form of nature reserves or national parks, have become increasingly more dominant as an international conservation strategy. An important factor in protected area management is the relationship between protected areas and its surrounding communities. Historically, the fortress conservation model based on the exclusion of human use and occupation prevailed in relation to protected areas. It is known that this approach brought with it many social and environmental injustices to local communities living in or adjacent to parks. However, a shift in conservation thinking occurred towards the end of the twentieth century, where it has increasingly been advocated for a more participatory approach in protected area management. South Africa has signed the international Convention on Biological Diversity that promotes a participatory approach to nature conservation, which is also reflected in the country’s national laws and policies. In relation to the literature and the lens of political ecology, this thesis sets out to assess in what ways and to what extent the participatory approach has been embraced by South Africa’s conservation authorities. As a case study, it looks at the Tsitsikamma National P ark ( incorporated into the larger Garden Route National Park). In order to get insight on h ow the participatory approach plays itself out at the T NP and what the nature of local communities’ relationship with the park is, this study looks at the aspects of (1) local communities’ socio-economic conditions, (2) their relationship with their natural environment, (3) their perception of nature conservation and (4) their perception of tourism. Then, taking all these aspects into account, (5) how local communities, in general, perceive their relationship with the p ark and its authorities. This study looked at the communities of Kurland, Nature’s Valley, Covie and Storms River. It shows in concurrence with other studies, that despite progressive laws and policies that express the intention of the South African state and SANParks to embrace the participatory approach, its implementation o n t he g round is riddled with challenges. , Thesis (MSocSc) -- Faculty of Humanities, Athropology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Le Fleur, Yvette Adele
- Date: 2021-04
- Subjects: National parks and reserves -- South Africa -- Eastern Cape , Protected areas -- Management , Programme of Work on Protected Areas , Human ecology -- South Africa -- Tsitsikamma , Nature conservation -- Citizen participation
- Language: English
- Type: thesis , text , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/177247 , vital:42803
- Description: Since the twentieth century, protected areas, usually in the form of nature reserves or national parks, have become increasingly more dominant as an international conservation strategy. An important factor in protected area management is the relationship between protected areas and its surrounding communities. Historically, the fortress conservation model based on the exclusion of human use and occupation prevailed in relation to protected areas. It is known that this approach brought with it many social and environmental injustices to local communities living in or adjacent to parks. However, a shift in conservation thinking occurred towards the end of the twentieth century, where it has increasingly been advocated for a more participatory approach in protected area management. South Africa has signed the international Convention on Biological Diversity that promotes a participatory approach to nature conservation, which is also reflected in the country’s national laws and policies. In relation to the literature and the lens of political ecology, this thesis sets out to assess in what ways and to what extent the participatory approach has been embraced by South Africa’s conservation authorities. As a case study, it looks at the Tsitsikamma National P ark ( incorporated into the larger Garden Route National Park). In order to get insight on h ow the participatory approach plays itself out at the T NP and what the nature of local communities’ relationship with the park is, this study looks at the aspects of (1) local communities’ socio-economic conditions, (2) their relationship with their natural environment, (3) their perception of nature conservation and (4) their perception of tourism. Then, taking all these aspects into account, (5) how local communities, in general, perceive their relationship with the p ark and its authorities. This study looked at the communities of Kurland, Nature’s Valley, Covie and Storms River. It shows in concurrence with other studies, that despite progressive laws and policies that express the intention of the South African state and SANParks to embrace the participatory approach, its implementation o n t he g round is riddled with challenges. , Thesis (MSocSc) -- Faculty of Humanities, Athropology, 2021
- Full Text:
- Date Issued: 2021-04
Ndiyazi ukuba ndiza kufa njani : ingqokelela yemibongo
- Authors: Mdliva, Mqhubi Given
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , Xhosa poetry -- 21st century , Xhosa poetry -- History and criticism , Diaries -- Authorship , Xhosa fiction -- 21st century
- Language: Xhosa
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178295 , vital:42928
- Description: Le mibongo inyathela kwizinto ezitsarhayo; ukufa, ukukhula kweziganeko ezingobundlobongela obuphathelele kwezesondo nesini, kubulawa abantwana namanina ngamadoda norhwaphilizo olugqugqisayo. Lo msebenzi uphonononga ukwavavanya ukusetyenziswa kweempawu zokubhala kungalandelwa miqathango yokubhala koko kusetyenziswa ezi mpawu njengezixhobo zokuphuhlisa iimvakalelo zembongi. Ezi mpawu ziquka iidesh, iikholoni, iisemikholoni ukuqelelaniswa kwamagama kukwashiywa nezikhewu phakathi kwamagama kukhokelwa ngumoya wemibongo. Oku kubangele ukuba le mibongo ibe nezakhiwo ezahlukileyo nezingaqhelekanga kubhalo lwesiXhosa. Oko kukuthi, lo msebenzi utyebisa uncwadi lwesiXhosa ngokukwandisa kule ndlela ingaqhelekanga yokubhala. Umsebenzi kaSt E.P. Yako ube nefuthe kakhulu kulo msebenzi, ngakumbi indlela alusebenzise ngayo ulwimi oluteketeke zizafobe nemifanekiso ukubhala imibongo njengoko enzile kumbongo othi, Izibongo zikaMhlekazi uArchie Sandile. Kumbhali uMarina Tsvetaete kubolekwe indlela ayisebenzise ngayo imifanekiso kumbongo osihloko sithi, Poems for Block kuba udubula ngegama uthi thaa umfanekiso kwingqondo yomfundi. Isimbo sokuyila isakhiwo sombongo sikaSimphiwe Nolutshungu naso sibe nefuthe kule mibongo, kwaye le thisisi yandisa apho lo kaNolutshungu aphele khona ngakumbi kwindlela asebenzise ngayo iimpawu zokubhala. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mdliva, Mqhubi Given
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , Xhosa poetry -- 21st century , Xhosa poetry -- History and criticism , Diaries -- Authorship , Xhosa fiction -- 21st century
- Language: Xhosa
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178295 , vital:42928
- Description: Le mibongo inyathela kwizinto ezitsarhayo; ukufa, ukukhula kweziganeko ezingobundlobongela obuphathelele kwezesondo nesini, kubulawa abantwana namanina ngamadoda norhwaphilizo olugqugqisayo. Lo msebenzi uphonononga ukwavavanya ukusetyenziswa kweempawu zokubhala kungalandelwa miqathango yokubhala koko kusetyenziswa ezi mpawu njengezixhobo zokuphuhlisa iimvakalelo zembongi. Ezi mpawu ziquka iidesh, iikholoni, iisemikholoni ukuqelelaniswa kwamagama kukwashiywa nezikhewu phakathi kwamagama kukhokelwa ngumoya wemibongo. Oku kubangele ukuba le mibongo ibe nezakhiwo ezahlukileyo nezingaqhelekanga kubhalo lwesiXhosa. Oko kukuthi, lo msebenzi utyebisa uncwadi lwesiXhosa ngokukwandisa kule ndlela ingaqhelekanga yokubhala. Umsebenzi kaSt E.P. Yako ube nefuthe kakhulu kulo msebenzi, ngakumbi indlela alusebenzise ngayo ulwimi oluteketeke zizafobe nemifanekiso ukubhala imibongo njengoko enzile kumbongo othi, Izibongo zikaMhlekazi uArchie Sandile. Kumbhali uMarina Tsvetaete kubolekwe indlela ayisebenzise ngayo imifanekiso kumbongo osihloko sithi, Poems for Block kuba udubula ngegama uthi thaa umfanekiso kwingqondo yomfundi. Isimbo sokuyila isakhiwo sombongo sikaSimphiwe Nolutshungu naso sibe nefuthe kule mibongo, kwaye le thisisi yandisa apho lo kaNolutshungu aphele khona ngakumbi kwindlela asebenzise ngayo iimpawu zokubhala. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
Night-time gravity waves detected with multi-frequency airglow imager
- Authors: Machubeng, Karabo Pebane
- Date: 2021-04
- Subjects: Gravity waves , Airglow , Gravity waves -- Seasonal variations , All Sky Imager
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178341 , vital:42931
- Description: This thesis shows the statistics of atmospheric gravity waves (AGWs) observed in the OI emission 557.7 nm at _97 km altitude using an all-sky imager based in Sutherland, South Africa (32.37_ S, 20.81_ E) in the year 2017. The wavelengths were determined using the propagation vector method, velocity was determined using the cross correlation of 1D FFT and the period was determined using the equation that relates wavelength and velocity. It was found that the horizontal wavelength in summer was almost evenly distributed between 10 and 40 km and for autumn, winter and spring were mostly between 10 and 30 km. The favoured speeds were between 40 and 50 m/s in autumn, as well as 30 and 50 m/s in summer, but the AGWs in winter had a bimodal speed distribution of 20 - 40 and 50 - 70 m/s. The majority of periods observed in all seasons were less than 20 minutes with a dominant peak of 5 - 10 minutes in autumn and spring. There was no favoured propagation direction for spring, but AGWs favoured a southeastward propagation in summer, and a southward propagation in autumn and winter. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Machubeng, Karabo Pebane
- Date: 2021-04
- Subjects: Gravity waves , Airglow , Gravity waves -- Seasonal variations , All Sky Imager
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178341 , vital:42931
- Description: This thesis shows the statistics of atmospheric gravity waves (AGWs) observed in the OI emission 557.7 nm at _97 km altitude using an all-sky imager based in Sutherland, South Africa (32.37_ S, 20.81_ E) in the year 2017. The wavelengths were determined using the propagation vector method, velocity was determined using the cross correlation of 1D FFT and the period was determined using the equation that relates wavelength and velocity. It was found that the horizontal wavelength in summer was almost evenly distributed between 10 and 40 km and for autumn, winter and spring were mostly between 10 and 30 km. The favoured speeds were between 40 and 50 m/s in autumn, as well as 30 and 50 m/s in summer, but the AGWs in winter had a bimodal speed distribution of 20 - 40 and 50 - 70 m/s. The majority of periods observed in all seasons were less than 20 minutes with a dominant peak of 5 - 10 minutes in autumn and spring. There was no favoured propagation direction for spring, but AGWs favoured a southeastward propagation in summer, and a southward propagation in autumn and winter. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
Observations of cosmic re-ionisation with the Hydrogen Epoch of Reionization Array: simulations of closure phase spectra
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04
Perceptions of the role of Lantana camara on human well-being and rural livelihoods in Vhembe Biosphere Reserve, South Africa
- Authors: Mhlongo, Edward Swazi
- Date: 2021-04
- Subjects: Lantana camara -- South Africa -- Vhembe District Municipality , Introduced organisms -- South Africa -- Vhembe District Municipality , Biological invasions -- South Africa -- Vhembe District Municipality , Plant invasions -- South Africa -- Vhembe District Municipality , Lantana camara -- Control -- South Africa -- Vhembe District Municipality , South Africa -- Rural conditions , Ethnoscience -- South Africa -- Vhembe District Municipality
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177952 , vital:42893
- Description: In the past, social aspects on biological invasions were less documented, this hindered the development of sound and effective management of Invasive Alien Species (IAS). However, there has been a shift in trends with more studies on biological invasions integrating local knowledge together with ecological studies to develop effective management interventions. Invasive Alien Species are widespread throughout Southern Africa and are usually prevalent in the rural areas. Limpopo province consists of large rural areas where people depend on natural resources, wild and exotic species for their livelihoods. Lantana camara is one of the major invaders that is problematic worldwide having detrimental impacts on biodiversity, ecosystem functions, and economies. This study assessed the perceptions of the role of L. camara on the well-being and rural livelihoods of local communities in the Vhembe Biosphere Reserve using household surveys. A total of 300 surveys were administered in six villages. The study further used a two-pronged approach to examine invasion extent and management options. The two-pronged approach included (i) detailed vegetation surveys in 50 household yards within each village, and (ii) focus group to solicit local knowledge of invasion extent and managing L. camara by the rural communities. The results of the study showed that almost all the respondents knew L. camara and could describe it. Most of the respondents were of the view that L. camara had no negative impacts on their livelihoods. Other respondents stated costs associated with L. camara were more than benefits and wanted a reduction in L. camara densities in the area. Most respondents wanted more government intervention to help in managing L. camara, this is because of the perceived future impacts of L. camara. Vegetation survey results showed no significant difference in L. camara abundances and plant heights among the six study villages. The average number of L. camara counted per household yard in all villages was (2.41 ± 0.20) plants, with average plant basal diameter of (0.94 ± 0.02 cm). There were significant differences in canopy width of L. camara among the six study villages. Plant basal diameter was high in Tshakhuma (1.05 ± 0.04 m) and Duthuni (1.00 ± 0.04 m) villages, and low in Ha Mutsha village (0.82 ± 0.03 m). Lantana camara canopy width at household level across all villages averaged 1.34 ± 0.03 m. Canopy cover was high in Tshakhuma village (1.70 ± 0.09 m) and low at Ha Mutsha village (1.03 ± 0.03 m). In all six village focus group discussions, it was noted that mechanical clearing of L. camara was the most used method, but they reported minimum help from the government particularly Working for Water (WfW). The study concludes that L. camara has no substantial adverse impacts to most of the respondents. The study further noted that L. camara is dominant in most household yards ii and that management is taking place however current control options are not enough on their own. Suggestions for further research are to explore more alternative indigenous species present or easily accessible to the community members which may offer the same benefits as IAS. Furthermore, additional research at local level is required for implementing management techniques best suited for the area. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mhlongo, Edward Swazi
- Date: 2021-04
- Subjects: Lantana camara -- South Africa -- Vhembe District Municipality , Introduced organisms -- South Africa -- Vhembe District Municipality , Biological invasions -- South Africa -- Vhembe District Municipality , Plant invasions -- South Africa -- Vhembe District Municipality , Lantana camara -- Control -- South Africa -- Vhembe District Municipality , South Africa -- Rural conditions , Ethnoscience -- South Africa -- Vhembe District Municipality
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177952 , vital:42893
- Description: In the past, social aspects on biological invasions were less documented, this hindered the development of sound and effective management of Invasive Alien Species (IAS). However, there has been a shift in trends with more studies on biological invasions integrating local knowledge together with ecological studies to develop effective management interventions. Invasive Alien Species are widespread throughout Southern Africa and are usually prevalent in the rural areas. Limpopo province consists of large rural areas where people depend on natural resources, wild and exotic species for their livelihoods. Lantana camara is one of the major invaders that is problematic worldwide having detrimental impacts on biodiversity, ecosystem functions, and economies. This study assessed the perceptions of the role of L. camara on the well-being and rural livelihoods of local communities in the Vhembe Biosphere Reserve using household surveys. A total of 300 surveys were administered in six villages. The study further used a two-pronged approach to examine invasion extent and management options. The two-pronged approach included (i) detailed vegetation surveys in 50 household yards within each village, and (ii) focus group to solicit local knowledge of invasion extent and managing L. camara by the rural communities. The results of the study showed that almost all the respondents knew L. camara and could describe it. Most of the respondents were of the view that L. camara had no negative impacts on their livelihoods. Other respondents stated costs associated with L. camara were more than benefits and wanted a reduction in L. camara densities in the area. Most respondents wanted more government intervention to help in managing L. camara, this is because of the perceived future impacts of L. camara. Vegetation survey results showed no significant difference in L. camara abundances and plant heights among the six study villages. The average number of L. camara counted per household yard in all villages was (2.41 ± 0.20) plants, with average plant basal diameter of (0.94 ± 0.02 cm). There were significant differences in canopy width of L. camara among the six study villages. Plant basal diameter was high in Tshakhuma (1.05 ± 0.04 m) and Duthuni (1.00 ± 0.04 m) villages, and low in Ha Mutsha village (0.82 ± 0.03 m). Lantana camara canopy width at household level across all villages averaged 1.34 ± 0.03 m. Canopy cover was high in Tshakhuma village (1.70 ± 0.09 m) and low at Ha Mutsha village (1.03 ± 0.03 m). In all six village focus group discussions, it was noted that mechanical clearing of L. camara was the most used method, but they reported minimum help from the government particularly Working for Water (WfW). The study concludes that L. camara has no substantial adverse impacts to most of the respondents. The study further noted that L. camara is dominant in most household yards ii and that management is taking place however current control options are not enough on their own. Suggestions for further research are to explore more alternative indigenous species present or easily accessible to the community members which may offer the same benefits as IAS. Furthermore, additional research at local level is required for implementing management techniques best suited for the area. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-04
Photodynamic antimicrobial chemotherapy against Staphylococcus aureus and Escherichia coli sensitized using indium (III) cationic porphyrins linked to core-shell magnetic nanoparticles
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
Physical activity, physical fitness, sedentary behaviour and screen time profiles of primary school children in a school within the Makana Municipality, Eastern Cape, South Africa
- Authors: Kade, Andréa Gaby
- Date: 2021-04
- Subjects: Sedentary behavior in children -- South Africa -- Makana Municipality , Physical fitness for children -- South Africa -- Makana Municipality , Exercise -- Physiological aspects , Exercise -- Health aspects , Diabetes -- Risk factors , Heart -- Diseases -- Risk factors
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177282 , vital:42806
- Description: There is a lack of data on the physical activity, physical fitness and sedentary behaviour of children in South Africa. Furthermore chronic diseases such as type II diabetes and coronary heart disease have been linked to childhood inactivity, and improving cardiorespiratory fitness and increasing levels of physical activity has been shown to be beneficial in reducing the risk of such diseases. In South Africa more broadly there is a lack of information on levels of physical activity and sedentary behaviour as well as physical fitness measures particularly in children. Objective: The purpose of this study was to enhance the existing body of knowledge on this, by measuring the prevalence of physical inactivity, sedentary behaviour and screen time of primary school children in a private school from the Makana Municipal region in the Eastern Cape Province of South Africa, where the evidence is most sparse. A secondary aim was to assess levels of physical fitness in this cohort, as well as to compare across grades and sexes. Method: After ethical approval was granted, stature and body mass measurements were taken and body mass index was computed for primary school children (Grade one to seven) from a private school in the Makana Municipality. Sitting stature was measured in order to determine each child’s peak height velocity and maturity offset. Five different physical fitness tests were conducted on the children and blood pressure and heart rate values were measured at rest. Physical activity and screen time questionnaires were completed by the children’s parents for a seven day period. Results: Females were found to mature faster than males. In addition females were more physically active (Females= 916 min/week; Males= 669 min/week) while also accumulating more sedentary time (Females= 1241 min/week; Males= 970 min/week) as compared to males, although no significant differences were found between males and females for these variables. The sample participated in more than 60 minutes of moderate-to-vigorous physical activity and less than two hours of screen time daily, which is in accordance with guidelines. No differences were found between grades and sexes for accumulated screen time. Strength increased significantly with grade and age, and there were also statistical differences between the sexes for all three strength measures with males being stronger than females. Females were more flexible than males and no statistical differences were found between sexes for the shuttle run test. Blood pressure correlated positively with mass, as did all the strength measures as well as maturity offset. No correlations were found between screen time and all other variables. A negative relationship was recorded between screen time and physical activity, although not significant. For females a strong positive correlation was found between sedentary behaviour and physical activity. Conclusion: The study was successful in adding to the body of knowledge regarding the prevalence of physical inactivity, sedentary behaviour and screen time within school children from the Makana Municipality in the Eastern Cape Province of South Africa. The sample was considered physically active as they accumulated on average more than 60 minutes of moderate-to-vigorous physical activity daily (Males= 96 min/day; Females 130 min/day), which is in accordance with guidelines recommended by the World Health Organization (World Health Organization, 2018). The sample accumulated more sedentary behaviour than physical activity, although not significant. Screen time was below regulations of two hours daily, indicating this population participated in more non screen related sedentary behaviour. More research is needed into the risks presented with different forms of sedentary behaviour. Physical fitness increased with increasing grade and age and males were considerably more fit. The current study did not present any concern with regards to the effects of increased physical activity and fitness levels within school aged children. More research into the current levels of physical activity, physical fitness and sedentary behaviour of school aged children in South Africa in general, and in the Eastern Cape Province, is needed. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Kade, Andréa Gaby
- Date: 2021-04
- Subjects: Sedentary behavior in children -- South Africa -- Makana Municipality , Physical fitness for children -- South Africa -- Makana Municipality , Exercise -- Physiological aspects , Exercise -- Health aspects , Diabetes -- Risk factors , Heart -- Diseases -- Risk factors
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177282 , vital:42806
- Description: There is a lack of data on the physical activity, physical fitness and sedentary behaviour of children in South Africa. Furthermore chronic diseases such as type II diabetes and coronary heart disease have been linked to childhood inactivity, and improving cardiorespiratory fitness and increasing levels of physical activity has been shown to be beneficial in reducing the risk of such diseases. In South Africa more broadly there is a lack of information on levels of physical activity and sedentary behaviour as well as physical fitness measures particularly in children. Objective: The purpose of this study was to enhance the existing body of knowledge on this, by measuring the prevalence of physical inactivity, sedentary behaviour and screen time of primary school children in a private school from the Makana Municipal region in the Eastern Cape Province of South Africa, where the evidence is most sparse. A secondary aim was to assess levels of physical fitness in this cohort, as well as to compare across grades and sexes. Method: After ethical approval was granted, stature and body mass measurements were taken and body mass index was computed for primary school children (Grade one to seven) from a private school in the Makana Municipality. Sitting stature was measured in order to determine each child’s peak height velocity and maturity offset. Five different physical fitness tests were conducted on the children and blood pressure and heart rate values were measured at rest. Physical activity and screen time questionnaires were completed by the children’s parents for a seven day period. Results: Females were found to mature faster than males. In addition females were more physically active (Females= 916 min/week; Males= 669 min/week) while also accumulating more sedentary time (Females= 1241 min/week; Males= 970 min/week) as compared to males, although no significant differences were found between males and females for these variables. The sample participated in more than 60 minutes of moderate-to-vigorous physical activity and less than two hours of screen time daily, which is in accordance with guidelines. No differences were found between grades and sexes for accumulated screen time. Strength increased significantly with grade and age, and there were also statistical differences between the sexes for all three strength measures with males being stronger than females. Females were more flexible than males and no statistical differences were found between sexes for the shuttle run test. Blood pressure correlated positively with mass, as did all the strength measures as well as maturity offset. No correlations were found between screen time and all other variables. A negative relationship was recorded between screen time and physical activity, although not significant. For females a strong positive correlation was found between sedentary behaviour and physical activity. Conclusion: The study was successful in adding to the body of knowledge regarding the prevalence of physical inactivity, sedentary behaviour and screen time within school children from the Makana Municipality in the Eastern Cape Province of South Africa. The sample was considered physically active as they accumulated on average more than 60 minutes of moderate-to-vigorous physical activity daily (Males= 96 min/day; Females 130 min/day), which is in accordance with guidelines recommended by the World Health Organization (World Health Organization, 2018). The sample accumulated more sedentary behaviour than physical activity, although not significant. Screen time was below regulations of two hours daily, indicating this population participated in more non screen related sedentary behaviour. More research is needed into the risks presented with different forms of sedentary behaviour. Physical fitness increased with increasing grade and age and males were considerably more fit. The current study did not present any concern with regards to the effects of increased physical activity and fitness levels within school aged children. More research into the current levels of physical activity, physical fitness and sedentary behaviour of school aged children in South Africa in general, and in the Eastern Cape Province, is needed. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-04
Poppehysie
- Authors: Arendse, Ashwin Albert
- Date: 2021-04
- Subjects: Kaaps , Creative writing (Higher education) -- South Africa , Diaries -- Authorship , Afrikaans poetry -- 21st century , African literature -- History and criticism
- Language: Afrikaans
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178259 , vital:42925
- Description: My thesis, is geskryf in Swartlandse Kaaps, ’n streeksvariant van Kaaps. Die poems is free verses wat afspeel tien ie backdrop van Malmesbury en Stellenbosch se “Coloured areas” mette analysis van dialect en ideolect wat eie is annie mense wat ampe altyd feature innie stories wat ek vertel. Die thesis explore die liefde asse konsep. Dit kyk na hoe die desperate need vi absent liefde ’n toxic relationship feed tussen ’n jong couple ennie destructive impact van liefde oppe pesoon wie nooit geleer was hoe om lief te wies vi annes ie. Dan kyk ek oek na hoe die previous generations, dit van my ma en pa liefde reject et asse unaffordable excess inne community wat brutal en harsh is. Antonio Gramsci se konsep vannie organic intellectual, dien asse philosophical underpinning virrie thesis d.w.s die hoofkarakter dien asse orator virrie intellectual en cultural insights wattie everyman in sy community nie self kan express ie. Die organic intellectual express díe thoughts innie cultural taal van sy social class. Die thesis explore stories soes it vetel wôd dee mense soes my oupa en mense wattie altyd aware is dat hulle stories in hulle in hettie. In dai way val it tot some degree binne die terrain van oral traditions. Die thesis wil dip into die collective conscious vanne social group wat die worst aspects van liewe in Syd-Afrika experience et. Ek voel free verse is ie ideal form van expression vi my in regards tot die skryf van die thesis, omdat ek daamee die line successfully kan blur tussen ie ‘language of the people’ en my eie individual leaning toward poetic language en forms. In terms van style draw ek op vorige digbundels in Kaaps, most notably op Nathan Trantraal se baie controlled, free verse digbundel, ‘Alles het niet kom wôd,’en Ronelda S. Kamfer se technique van ‘oorvertel’, in haa digbundel ‘grond/Santekraam’. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Arendse, Ashwin Albert
- Date: 2021-04
- Subjects: Kaaps , Creative writing (Higher education) -- South Africa , Diaries -- Authorship , Afrikaans poetry -- 21st century , African literature -- History and criticism
- Language: Afrikaans
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178259 , vital:42925
- Description: My thesis, is geskryf in Swartlandse Kaaps, ’n streeksvariant van Kaaps. Die poems is free verses wat afspeel tien ie backdrop van Malmesbury en Stellenbosch se “Coloured areas” mette analysis van dialect en ideolect wat eie is annie mense wat ampe altyd feature innie stories wat ek vertel. Die thesis explore die liefde asse konsep. Dit kyk na hoe die desperate need vi absent liefde ’n toxic relationship feed tussen ’n jong couple ennie destructive impact van liefde oppe pesoon wie nooit geleer was hoe om lief te wies vi annes ie. Dan kyk ek oek na hoe die previous generations, dit van my ma en pa liefde reject et asse unaffordable excess inne community wat brutal en harsh is. Antonio Gramsci se konsep vannie organic intellectual, dien asse philosophical underpinning virrie thesis d.w.s die hoofkarakter dien asse orator virrie intellectual en cultural insights wattie everyman in sy community nie self kan express ie. Die organic intellectual express díe thoughts innie cultural taal van sy social class. Die thesis explore stories soes it vetel wôd dee mense soes my oupa en mense wattie altyd aware is dat hulle stories in hulle in hettie. In dai way val it tot some degree binne die terrain van oral traditions. Die thesis wil dip into die collective conscious vanne social group wat die worst aspects van liewe in Syd-Afrika experience et. Ek voel free verse is ie ideal form van expression vi my in regards tot die skryf van die thesis, omdat ek daamee die line successfully kan blur tussen ie ‘language of the people’ en my eie individual leaning toward poetic language en forms. In terms van style draw ek op vorige digbundels in Kaaps, most notably op Nathan Trantraal se baie controlled, free verse digbundel, ‘Alles het niet kom wôd,’en Ronelda S. Kamfer se technique van ‘oorvertel’, in haa digbundel ‘grond/Santekraam’. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
Salt in my footsteps
- Authors: Radebe, Mxolisi Vusumuzi
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , South African poetry (English) -- 21st century , South African fiction (English) -- 21st century
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178201 , vital:42920
- Description: My thesis is a collection of poems which focus on human experiences related to my background. I grew up in a countryside village, freely experiencing nature in unrestricted walks to the rivers and mountains; communal living instilled in me the humanitarian values which I uphold to the present. I use short and long lyrical prose poems to bring life and humanise the untold or unexpressed stories of my community. My use of simple everyday language and clear, concrete but surprising images that resonate with deeper meanings and emotions is influenced by Seitlhamo Motsapi’s poems, especially his collection of poems titled earthstepper/the ocean is very shallow and Mxolisi Nyezwa’s poetry book, Song Trials. Spanish poems in English translations by the 20th century Spanish poets: Blas de Otero, Juan Roman Jimenez and Federico Garcia Lorca, published in the book titled Roots and Wings have had a huge impact on my construction of images. I also draw from the free-form and narrative prose poetry experiments of poets: Mangaliso Buzani, vangile gantsho and Ivy Alvarez. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Radebe, Mxolisi Vusumuzi
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , South African poetry (English) -- 21st century , South African fiction (English) -- 21st century
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178201 , vital:42920
- Description: My thesis is a collection of poems which focus on human experiences related to my background. I grew up in a countryside village, freely experiencing nature in unrestricted walks to the rivers and mountains; communal living instilled in me the humanitarian values which I uphold to the present. I use short and long lyrical prose poems to bring life and humanise the untold or unexpressed stories of my community. My use of simple everyday language and clear, concrete but surprising images that resonate with deeper meanings and emotions is influenced by Seitlhamo Motsapi’s poems, especially his collection of poems titled earthstepper/the ocean is very shallow and Mxolisi Nyezwa’s poetry book, Song Trials. Spanish poems in English translations by the 20th century Spanish poets: Blas de Otero, Juan Roman Jimenez and Federico Garcia Lorca, published in the book titled Roots and Wings have had a huge impact on my construction of images. I also draw from the free-form and narrative prose poetry experiments of poets: Mangaliso Buzani, vangile gantsho and Ivy Alvarez. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
Selection for improved virulence of Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) to False Codling Moth, Thaumatotibia leucotreta, by serial passage through a heterologous host
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
Student protests in South African universities with specific reference to Rhodes University (1970-1994)
- Authors: Gillam, Katherine Elaine
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178457 , vital:42941
- Description: Access restricted until April 2023. , Thesis (MA) -- Faculty of Humanities, History, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Gillam, Katherine Elaine
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178457 , vital:42941
- Description: Access restricted until April 2023. , Thesis (MA) -- Faculty of Humanities, History, 2021
- Full Text:
- Date Issued: 2021-04
The application of Classification Trees in the Banking Sector
- Authors: Mtwa, Sithayanda
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178514 , vital:42946
- Description: Access restricted until April 2026. , Thesis (MSc) -- Faculty of Science, Statistics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mtwa, Sithayanda
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178514 , vital:42946
- Description: Access restricted until April 2026. , Thesis (MSc) -- Faculty of Science, Statistics, 2021
- Full Text:
- Date Issued: 2021-04
The development of an ionospheric storm-time index for the South African region
- Authors: Tshisaphungo, Mpho
- Date: 2021-04
- Subjects: Ionospheric storms -- South Africa , Global Positioning System , Neural networks (Computer science) , Regression analysis , Ionosondes , Auroral electrojet , Geomagnetic indexes , Magnetic storms -- South Africa
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178409 , vital:42937 , 10.21504/10962/178409
- Description: This thesis presents the development of a regional ionospheric storm-time model which forms the foundation of an index to provide a quick view of the ionospheric storm effects over South African mid-latitude region. The model is based on the foF2 measurements from four South African ionosonde stations. The data coverage for the model development over Grahamstown (33.3◦S, 26.5◦E), Hermanus (34.42◦S, 19.22◦E), Louisvale (28.50◦S, 21.20◦E), and Madimbo (22.39◦S, 30.88◦E) is 1996-2016, 2009-2016, 2000-2016, and 2000-2016 respectively. Data from the Global Positioning System (GPS) and radio occultation (RO) technique were used during validation. As the measure of either positive or negative storm effect, the variation of the critical frequency of the F2 layer (foF2) from the monthly median values (denoted as _foF2) is modeled. The modeling of _foF2 is based on only storm time data with the criteria of Dst 6 -50 nT and Kp > 4. The modeling methods used in the study were artificial neural network (ANN), linear regression (LR) and polynomial functions. The approach taken was to first test the modeling techniques on a single station before expanding the study to cover the regional aspect. The single station modeling was developed based on ionosonde data over Grahamstown. The inputs for the model which related to seasonal variation, diurnal variation, geomagnetic activity and solar activity were considered. For the geomagnetic activity, three indices namely; the symmetric disturbance in the horizontal component of the Earth’s magnetic field (SYM − H), the Auroral Electrojet (AE) index and local geomagnetic index A, were included as inputs. The performance of a single station model revealed that, of the three geomagnetic indices, SYM − H index has the largest contribution of 41% and 54% based on ANN and LR techniques respectively. The average correlation coefficients (R) for both ANN and LR models was 0.8, when validated during the selected storms falling within the period of model development. When validated using storms that fall outside the period of model development, the model gave R values of 0.6 and 0.5 for ANN and LR respectively. In addition, the GPS total electron content (TEC) derived measurements were used to estimate foF2 data. This is because there are more GPS receivers than ionosonde locations and the utilisation of this data increases the spatial coverage of the regional model. The estimation of foF2 from GPS TEC was done at GPS-ionosonde co-locations using polynomial functions. The average R values of 0.69 and 0.65 were obtained between actual and derived _foF2 over the co-locations and other GPS stations respectively. Validation of GPS TEC derived foF2 with RO data over regions out of ionospheric pierce points coverage with respect to ionosonde locations gave R greater than 0.9 for the selected storm period of 4-8 August 2011. The regional storm-time model was then developed based on the ANN technique using the four South African ionosonde stations. The maximum and minimum R values of 0.6 and 0.5 were obtained over ionosonde and GPS locations respectively. This model forms the basis towards the regional ionospheric storm-time index. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Tshisaphungo, Mpho
- Date: 2021-04
- Subjects: Ionospheric storms -- South Africa , Global Positioning System , Neural networks (Computer science) , Regression analysis , Ionosondes , Auroral electrojet , Geomagnetic indexes , Magnetic storms -- South Africa
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178409 , vital:42937 , 10.21504/10962/178409
- Description: This thesis presents the development of a regional ionospheric storm-time model which forms the foundation of an index to provide a quick view of the ionospheric storm effects over South African mid-latitude region. The model is based on the foF2 measurements from four South African ionosonde stations. The data coverage for the model development over Grahamstown (33.3◦S, 26.5◦E), Hermanus (34.42◦S, 19.22◦E), Louisvale (28.50◦S, 21.20◦E), and Madimbo (22.39◦S, 30.88◦E) is 1996-2016, 2009-2016, 2000-2016, and 2000-2016 respectively. Data from the Global Positioning System (GPS) and radio occultation (RO) technique were used during validation. As the measure of either positive or negative storm effect, the variation of the critical frequency of the F2 layer (foF2) from the monthly median values (denoted as _foF2) is modeled. The modeling of _foF2 is based on only storm time data with the criteria of Dst 6 -50 nT and Kp > 4. The modeling methods used in the study were artificial neural network (ANN), linear regression (LR) and polynomial functions. The approach taken was to first test the modeling techniques on a single station before expanding the study to cover the regional aspect. The single station modeling was developed based on ionosonde data over Grahamstown. The inputs for the model which related to seasonal variation, diurnal variation, geomagnetic activity and solar activity were considered. For the geomagnetic activity, three indices namely; the symmetric disturbance in the horizontal component of the Earth’s magnetic field (SYM − H), the Auroral Electrojet (AE) index and local geomagnetic index A, were included as inputs. The performance of a single station model revealed that, of the three geomagnetic indices, SYM − H index has the largest contribution of 41% and 54% based on ANN and LR techniques respectively. The average correlation coefficients (R) for both ANN and LR models was 0.8, when validated during the selected storms falling within the period of model development. When validated using storms that fall outside the period of model development, the model gave R values of 0.6 and 0.5 for ANN and LR respectively. In addition, the GPS total electron content (TEC) derived measurements were used to estimate foF2 data. This is because there are more GPS receivers than ionosonde locations and the utilisation of this data increases the spatial coverage of the regional model. The estimation of foF2 from GPS TEC was done at GPS-ionosonde co-locations using polynomial functions. The average R values of 0.69 and 0.65 were obtained between actual and derived _foF2 over the co-locations and other GPS stations respectively. Validation of GPS TEC derived foF2 with RO data over regions out of ionospheric pierce points coverage with respect to ionosonde locations gave R greater than 0.9 for the selected storm period of 4-8 August 2011. The regional storm-time model was then developed based on the ANN technique using the four South African ionosonde stations. The maximum and minimum R values of 0.6 and 0.5 were obtained over ionosonde and GPS locations respectively. This model forms the basis towards the regional ionospheric storm-time index. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
The development of grade one teachers’ mathematics and pedagogical content knowledge through participation in a collaborative intervention
- Authors: Mutlane, Kedisaletse Stella
- Date: 2021-04
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa -- Northern Cape , Pedagogical content knowledge , Mathematics teachers -- Training of -- South Africa -- Northern Cape , Lesson planning -- South Africa -- Northern Cape , Teaching teams -- South Africa -- Northern Cape , Cultural Historical Activity Theory (CHAT)
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177370 , vital:42815
- Description: The “South African education system is grossly inefficient, severely underperforming and egregiously unfair” (Spaull, 2013, p.3). In particular, grave concerns with learner performance in mathematics in South Africa are well documented (e.g., Taylor, 2008; Spaull, 2013; Venkat & Spaull, 2015). There are various explanations for the poor state of learner performance in mathematics in South Africa. Two of the explanations that relate closely to my research interest are teachers’ insufficient mathematics content and pedagogical knowledge, and inappropriate professional development. This study aims to ascertain how a collaborative intervention can develop teachers’ mathematics and pedagogical content knowledge as they focus on developing learners’ foundational number sense. Cultural Historical Activity Theory, together with Mathematics Knowledge for Teaching (Ball et al., 2008) and the Knowledge Quartet (Rowlands & Turner, 2007) frameworks, provide the explanatory and analytic tools for the research. The research is a qualitative case study underpinned by an interpretivist orientation. The study was conducted at a township public primary school in the Northern Cape. Three Grade One teachers participated in the research. Data was collected through interviews, classroom observations, and videos of collaborative lesson planning and reflection sessions. A key finding emerging from this research is that the teachers had the necessary mathematics content knowledge to teach Grade One mathematics. Despite this and in contrast to it, they lacked adequate pedagogical content knowledge required to develop learners’ number sense. To develop their pedagogical content knowledge, they required the intervention of a ‘more knowledgable other’ (Vygotsky, 2008). Several contradictions and tensions emerged from the research. For example, the teachers expressed that the opportunity to work collaboratively was beneficial, but it was evident that they were familiar with and accomplished in planning and working together. The contradictions emerging from this research provide an opportunity and basis for expansive learning for future collaborative teacher endeavours. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mutlane, Kedisaletse Stella
- Date: 2021-04
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa -- Northern Cape , Pedagogical content knowledge , Mathematics teachers -- Training of -- South Africa -- Northern Cape , Lesson planning -- South Africa -- Northern Cape , Teaching teams -- South Africa -- Northern Cape , Cultural Historical Activity Theory (CHAT)
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177370 , vital:42815
- Description: The “South African education system is grossly inefficient, severely underperforming and egregiously unfair” (Spaull, 2013, p.3). In particular, grave concerns with learner performance in mathematics in South Africa are well documented (e.g., Taylor, 2008; Spaull, 2013; Venkat & Spaull, 2015). There are various explanations for the poor state of learner performance in mathematics in South Africa. Two of the explanations that relate closely to my research interest are teachers’ insufficient mathematics content and pedagogical knowledge, and inappropriate professional development. This study aims to ascertain how a collaborative intervention can develop teachers’ mathematics and pedagogical content knowledge as they focus on developing learners’ foundational number sense. Cultural Historical Activity Theory, together with Mathematics Knowledge for Teaching (Ball et al., 2008) and the Knowledge Quartet (Rowlands & Turner, 2007) frameworks, provide the explanatory and analytic tools for the research. The research is a qualitative case study underpinned by an interpretivist orientation. The study was conducted at a township public primary school in the Northern Cape. Three Grade One teachers participated in the research. Data was collected through interviews, classroom observations, and videos of collaborative lesson planning and reflection sessions. A key finding emerging from this research is that the teachers had the necessary mathematics content knowledge to teach Grade One mathematics. Despite this and in contrast to it, they lacked adequate pedagogical content knowledge required to develop learners’ number sense. To develop their pedagogical content knowledge, they required the intervention of a ‘more knowledgable other’ (Vygotsky, 2008). Several contradictions and tensions emerged from the research. For example, the teachers expressed that the opportunity to work collaboratively was beneficial, but it was evident that they were familiar with and accomplished in planning and working together. The contradictions emerging from this research provide an opportunity and basis for expansive learning for future collaborative teacher endeavours. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
The Dragon in the News : how Malawian journalists perceive the political influence of China on news reporting in Malawi
- Authors: Nyirongo, Mwaona
- Date: 2021-04
- Subjects: Journalists -- Malawi , Journalism -- Malawi , Journalism -- Political aspects -- Malawi , Journalism -- Objectivity -- Malawi , China -- Foreign economic relations -- Malawi , Malawi -- Economic conditions , Malawi -- Politics and government
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/177907 , vital:42889
- Description: The arrival of China in Malawi has been characterised by a growing sense of uncertainty where academics and social commentators at large have expressed concern over the intentions of the super power in the country. There are fears that China would like to extend its influence to Malawi as part of a broader push, to have greater influence in global politics and economics. That push is in part exercised through the media. The thesis examined the perception of Malawian journalists on how news media reports on Chinese activities in Malawi. It used content analysis to understand how the mediascape had changed from 2001 – 2007 when China had not established diplomatic relations with Malawi, and January 2008 – 2020 when China had established diplomatic relations. The thesis examined these shifts in journalistic representations of China in Malawi and developed prompts and probes from which journalist interviews were conducted. From the content analysis, it appears there is a remarkable change in the way China has been covered from 2001 – 2020. From 2001 – 2007, Malawian media, especially The Daily Times, was very harsh on China, uncritically reproducing Western representations of China as an aggressive country with no respect for human rights and dignity. This changed after January 2008 when the media leaned towards tolerance and acknowledgement of Chinese activities. Through interviews, journalists have indicated that the Chinese government offers opportunities, such as scholarships, fellowships, and exchange visits to journalists, making it difficult for them to bite the finger that is feeding them. This ‘soft power’ is backed up by the repressive power of the Malawi government, which uses intimidation to force journalists to report in their favour, thereby helping create a positive picture for China in Malawi. Journalists report that the significant shifts in journalistic representations of China have been mirrored by changes in the conceptualisation of journalistic roles in Malawi’s mediascape. , Thesis (MA) -- Faculty of Humanities, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Nyirongo, Mwaona
- Date: 2021-04
- Subjects: Journalists -- Malawi , Journalism -- Malawi , Journalism -- Political aspects -- Malawi , Journalism -- Objectivity -- Malawi , China -- Foreign economic relations -- Malawi , Malawi -- Economic conditions , Malawi -- Politics and government
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/177907 , vital:42889
- Description: The arrival of China in Malawi has been characterised by a growing sense of uncertainty where academics and social commentators at large have expressed concern over the intentions of the super power in the country. There are fears that China would like to extend its influence to Malawi as part of a broader push, to have greater influence in global politics and economics. That push is in part exercised through the media. The thesis examined the perception of Malawian journalists on how news media reports on Chinese activities in Malawi. It used content analysis to understand how the mediascape had changed from 2001 – 2007 when China had not established diplomatic relations with Malawi, and January 2008 – 2020 when China had established diplomatic relations. The thesis examined these shifts in journalistic representations of China in Malawi and developed prompts and probes from which journalist interviews were conducted. From the content analysis, it appears there is a remarkable change in the way China has been covered from 2001 – 2020. From 2001 – 2007, Malawian media, especially The Daily Times, was very harsh on China, uncritically reproducing Western representations of China as an aggressive country with no respect for human rights and dignity. This changed after January 2008 when the media leaned towards tolerance and acknowledgement of Chinese activities. Through interviews, journalists have indicated that the Chinese government offers opportunities, such as scholarships, fellowships, and exchange visits to journalists, making it difficult for them to bite the finger that is feeding them. This ‘soft power’ is backed up by the repressive power of the Malawi government, which uses intimidation to force journalists to report in their favour, thereby helping create a positive picture for China in Malawi. Journalists report that the significant shifts in journalistic representations of China have been mirrored by changes in the conceptualisation of journalistic roles in Malawi’s mediascape. , Thesis (MA) -- Faculty of Humanities, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-04
The effect of plant-derived dietary protein sources on cultured abalone Haliotis midae (L. 1758) digestive physiology
- Authors: Wright, Jason Geoffrey
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa , Haliotis midae -- Nutrition -- South Africa , Haliotis midae -- Physiology -- South Africa , Haliotis midae -- South Africa -- Growth , Haliotis midae -- Digestive organs , Abalone culture -- South Africa , Plant proteins as feed
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176803 , vital:42760
- Description: The growth and feed conversion ratio of farmed abalone Haliotis midae (L. 1758) fed a formulated diet varies in feeds with different protein sources. To better understand this, the effect that various combinations of dietary soybean meal (SBM), sunflower meal (SFM) and fishmeal (FM) had on the digestive efficiency of farmed H. midae when included in a formulated feed, were assessed. The aim of this study was to investigate the effect that plant-based proteins had on abalone digestion and gut-bacterial profile of cultured adult abalone when combined with fishmeal. This was done by analysing the chymotrypsin (protease) and cellulase (carbohydrase) digestive enzyme activities from whole-gut sections of farmed abalone that were fed one of four diets for 12 months: FM-only, SBM-only, fishmeal and soybean meal (FM-SBM), and fishmeal and sunflower meal (FM-SFM). There were significant interactions between the diets, sampling date, and sex of the abalone, which had an influence on the cellulase activities in the digestive tracts of the animals. Those fed the SBM diet had the highest cellulase activity by the end of the sampling period (ANOVA; df = 9; F = 2.9; P = 0.005). The significant interactions between diet and sampling date influenced the chymotrypsin activities of abalone. Animals fed the FM diet had the highest activity of chymotrypsin for most of the sampling period (ANOVA; df = 9; F = 2.5; P = 0.01). Therefore, diet did have an impact on the cellulase and chymotrypsin activities of abalone fed either combination diets (FM-SBM; FM-SFM) or single protein diets (FM; SBM). The presence of plant material such as cellulose fibres in the diets containing plant proteins may have influenced the cellulase activity levels of each treatment as it would have stimulated endogenous and exogenous cellulase production. However, treatments with the highest crude fibre content, SBM and FM-SFM, resulted in differing activities. The activity levels of chymotrypsin may have been impacted by the protein type, presence of protein inhibitors and temporal changes in utilisation. Abalone fed the FM diet exhibited the highest chymotrypsin activities on sampling day 182, which was in summer. Animals fed the treatment diets containing fishmeal also developed their reproductive tissues, and may explain the low chymotrypsin activities in abalone fed SBM-only. Additionally, the presence of allergenic compounds would have influenced enzyme activity, as they would have negatively affected the nutrient utilisation and absorptive capacity. Fluctuations in water temperature may have had an effect on enzyme activity, as activities were highest during summer, when seawater temperatures are most variable. A change to lowered water temperatures are known to trigger the growth of digestive epithelial tissue in abalone to allow for increased enzyme secretions and nutrient absorption (Schaeffer et al. 2013). The effect that plant protein inclusion in abalone diets had on the gut-microbiota was revealed by analysing the differences in gut-bacterial community profiles, through the use of metagenomic sequencing. The relative abundance of the phylum Verrucomicrobia, class Verrcomicrobiae and the genus Rubritalea were highest in the SBM diet. These bacterial groups were also influenced by the plant material from soybean meal, as hydrolysed cellulose is broken down by cellulases, and allowed for the proliferation of Rubritalea bacteria due to them using cellobiose as an energy source. The presence of Bacteroidetes was due to the phyla having bacterial species that can breakdown proteins and species that can break down carbohydrates. The animal protein present in the composition of the FM diet had a positive influence on proteolytic Bacteroidetes growth. The high levels of cellulose from the plant fibres in the soybean meal-only diet (SBM) promoted growth of saccharolytic Bacteroidetes. Tenericutes bacteria’s prominence was due to the higher plant fibres from the soybean meal as some Mycoplasma are known to degrade polysaccharides. Therefore, exposure to formulated feeds with high levels of these plant materials would allow for high proliferation. The thesis established that plant-derived dietary proteins in formulated feeds result in an effect on digestive enzyme activity and a difference in the community structure of gut bacteria in H. midae abalone. The results from the current research highlight the importance of studying abalone gut physiology when investigating the impacts of formulated feed composition, and can be used as an additional factor when determining the efficacy of a dietary component. Further research on the gut-bacterial groups and different digestive enzymes of H. midae abalone is encouraged, in order to create a holistic view on their response to dietary plant proteins inclusion in formulated feeds, thus reducing the need for fishmeal protein. , Thesis (MSc)-- Rhodes University, Faculty of Science, Department of Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Wright, Jason Geoffrey
- Date: 2021-04
- Subjects: Haliotis midae -- South Africa , Haliotis midae -- Nutrition -- South Africa , Haliotis midae -- Physiology -- South Africa , Haliotis midae -- South Africa -- Growth , Haliotis midae -- Digestive organs , Abalone culture -- South Africa , Plant proteins as feed
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176803 , vital:42760
- Description: The growth and feed conversion ratio of farmed abalone Haliotis midae (L. 1758) fed a formulated diet varies in feeds with different protein sources. To better understand this, the effect that various combinations of dietary soybean meal (SBM), sunflower meal (SFM) and fishmeal (FM) had on the digestive efficiency of farmed H. midae when included in a formulated feed, were assessed. The aim of this study was to investigate the effect that plant-based proteins had on abalone digestion and gut-bacterial profile of cultured adult abalone when combined with fishmeal. This was done by analysing the chymotrypsin (protease) and cellulase (carbohydrase) digestive enzyme activities from whole-gut sections of farmed abalone that were fed one of four diets for 12 months: FM-only, SBM-only, fishmeal and soybean meal (FM-SBM), and fishmeal and sunflower meal (FM-SFM). There were significant interactions between the diets, sampling date, and sex of the abalone, which had an influence on the cellulase activities in the digestive tracts of the animals. Those fed the SBM diet had the highest cellulase activity by the end of the sampling period (ANOVA; df = 9; F = 2.9; P = 0.005). The significant interactions between diet and sampling date influenced the chymotrypsin activities of abalone. Animals fed the FM diet had the highest activity of chymotrypsin for most of the sampling period (ANOVA; df = 9; F = 2.5; P = 0.01). Therefore, diet did have an impact on the cellulase and chymotrypsin activities of abalone fed either combination diets (FM-SBM; FM-SFM) or single protein diets (FM; SBM). The presence of plant material such as cellulose fibres in the diets containing plant proteins may have influenced the cellulase activity levels of each treatment as it would have stimulated endogenous and exogenous cellulase production. However, treatments with the highest crude fibre content, SBM and FM-SFM, resulted in differing activities. The activity levels of chymotrypsin may have been impacted by the protein type, presence of protein inhibitors and temporal changes in utilisation. Abalone fed the FM diet exhibited the highest chymotrypsin activities on sampling day 182, which was in summer. Animals fed the treatment diets containing fishmeal also developed their reproductive tissues, and may explain the low chymotrypsin activities in abalone fed SBM-only. Additionally, the presence of allergenic compounds would have influenced enzyme activity, as they would have negatively affected the nutrient utilisation and absorptive capacity. Fluctuations in water temperature may have had an effect on enzyme activity, as activities were highest during summer, when seawater temperatures are most variable. A change to lowered water temperatures are known to trigger the growth of digestive epithelial tissue in abalone to allow for increased enzyme secretions and nutrient absorption (Schaeffer et al. 2013). The effect that plant protein inclusion in abalone diets had on the gut-microbiota was revealed by analysing the differences in gut-bacterial community profiles, through the use of metagenomic sequencing. The relative abundance of the phylum Verrucomicrobia, class Verrcomicrobiae and the genus Rubritalea were highest in the SBM diet. These bacterial groups were also influenced by the plant material from soybean meal, as hydrolysed cellulose is broken down by cellulases, and allowed for the proliferation of Rubritalea bacteria due to them using cellobiose as an energy source. The presence of Bacteroidetes was due to the phyla having bacterial species that can breakdown proteins and species that can break down carbohydrates. The animal protein present in the composition of the FM diet had a positive influence on proteolytic Bacteroidetes growth. The high levels of cellulose from the plant fibres in the soybean meal-only diet (SBM) promoted growth of saccharolytic Bacteroidetes. Tenericutes bacteria’s prominence was due to the higher plant fibres from the soybean meal as some Mycoplasma are known to degrade polysaccharides. Therefore, exposure to formulated feeds with high levels of these plant materials would allow for high proliferation. The thesis established that plant-derived dietary proteins in formulated feeds result in an effect on digestive enzyme activity and a difference in the community structure of gut bacteria in H. midae abalone. The results from the current research highlight the importance of studying abalone gut physiology when investigating the impacts of formulated feed composition, and can be used as an additional factor when determining the efficacy of a dietary component. Further research on the gut-bacterial groups and different digestive enzymes of H. midae abalone is encouraged, in order to create a holistic view on their response to dietary plant proteins inclusion in formulated feeds, thus reducing the need for fishmeal protein. , Thesis (MSc)-- Rhodes University, Faculty of Science, Department of Ichthyology and Fisheries Science, 2021
- Full Text:
- Date Issued: 2021-04
The effect of sectoral foreign direct investment on sectoral growth and sectoral employment in South Africa
- Authors: Paul, Bernice Nicole
- Date: 2021-04
- Subjects: Investments, Foreign -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Economic policy , Gross domestic product -- South Africa , UNCTAD-ICTSD Project on IPRs and Sustainable Development , Unemployment -- South Africa
- Language: English
- Type: thesis , text , Master , MCom
- Identifier: http://hdl.handle.net/10962/177964 , vital:42894
- Description: Over several decades past, developing countries have received increased amounts of Foreign Direct Investment (FDI). This form of investment has been welcomed because of the perceived benefits attached to it. FDI is seen as an important driver of economic development for many nations. For South Africa specifically, GDP growth rates have remained less than required, unemployment rates have reached staggering levels, poverty and inequality levels are increasing and the list goes on. Considering the perceived benefits of FDI, one may argue that FDI can play a crucial role in reducing the mentioned challenges facing the nation, however, only if directed to initiatives contributing to growth and employment. The 2015 Investment Policy Framework for Sustainable Development includes an action menu promoting investment in sectors relating to the achievement of the Sustainable Development Goals (SDGs). Therefore, this study is aimed at investigating the relationship between sector FDI and sector growth in addition to investigating the effect of sector FDI on sector employment over the period 2000Q1 to 2016Q4 for six of South Africa’s economic sectors. The reason for such a study is based on the premise that developing nations such as South Africa lack sound trade and industrial policies favorable to foreign investors. This then leads to the nation failing to attract higher volumes of FDI which could be used to address structural challenges facing the country. It is therefore important to identify sectors in which FDI has resulted in growth and employment so that when policies are considered, the right FDI is targeted. A comprehensive review of existing theoretical and empirical literature showed that FDI does result in economic growth for developed and developing countries, although FDI crowds out domestic investment in the short run. Literature on the effect of FDI on employment showed diverse effects. Some studies found FDI to increase employment overall, other studies found FDI to increase employment only during periods of restructuring and some studies found FDI to result in job losses. For South African sectors, the present study finds that the financial services sector receives the highest volume of South African FDI, followed by the mining and quarrying sector and the manufacturing, however, FDI in all six sectors under study is associated with increased growth and employment. This finding suggests that the financial services sector has received increased volumes of FDI as a result of financialization of the South African economy. It is this increased FDI in the financial services sector that is directed to income redistribution from the real sector to the finance sector. This study employed econometric techniques and methods of analysis to investigate the relationship between sector FDI and sector growth, and the effect of sector FDI on sector employment. Panel cointegration tests were conducted for all six sectors included in the study to establish if long run equilibrium relationships exist among integrated variables. The Johansen-Fisher panel cointegration test revealed that there is evidence of cointegration in four of the six sectors. Since cointegration was established, the study proceeded to perform the Dumitrescu-Hurlin panel causality analysis and estimate a Panel Vector Error Correction Model (VECM). Results from the causality analysis found a unidirectional causality relationship between FDI and GDP growth, while the panel VECM found FDI to have a significant effect on growth in all sectors. The Seemingly Unrelated Regression (SUR) model employed to investigate the effect of FDI on employment found FDI to have an insignificant effect on employment in all sectors included, although the signs of the coefficients suggest that FDI is associated with increased employment and rising wages is associated with increased productivity growth. Since this study finds that FDI is associated with increased GDP growth in all six sectors under study, policy makers should devise strategies to attract FDI in sectors such as the transportation, storage and communication sector and the electricity, gas and water sector as FDI in these sectors are associated with increased growth however, they receive very low levels of FDI. There are a number of reasons for this, therefore, government institutions and policy makers should investigate the reasons for these low levels of FDI inflows into these sectors so that they can devise further strategies to address these reasons and perhaps attract higher levels of FDI into these sectors. Spillover benefits play a major role in host nations participating in FDI therefore, prior to entering into bilateral treaty agreements, policy makers should ensure that foreign investors are compelled to create jobs, offer training and qualifications etc. through their investments so that some of the SDGs can be achieved. Additionally, this study finds a positive, statistically insignificant relationship between FDI and employment. FDI may not have a significant relationship on employment due to jobless growth and capital-intensive growth rather than labor-intensive growth. Such a situation calls for government intervention. Skills shortage is a rising problem in South Africa; therefore, investors choose to employ advanced technologies rather than people. Under such circumstances, governments are encouraged to invest resources into skills development so that human capital are not completely replaced by technology. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Paul, Bernice Nicole
- Date: 2021-04
- Subjects: Investments, Foreign -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Economic policy , Gross domestic product -- South Africa , UNCTAD-ICTSD Project on IPRs and Sustainable Development , Unemployment -- South Africa
- Language: English
- Type: thesis , text , Master , MCom
- Identifier: http://hdl.handle.net/10962/177964 , vital:42894
- Description: Over several decades past, developing countries have received increased amounts of Foreign Direct Investment (FDI). This form of investment has been welcomed because of the perceived benefits attached to it. FDI is seen as an important driver of economic development for many nations. For South Africa specifically, GDP growth rates have remained less than required, unemployment rates have reached staggering levels, poverty and inequality levels are increasing and the list goes on. Considering the perceived benefits of FDI, one may argue that FDI can play a crucial role in reducing the mentioned challenges facing the nation, however, only if directed to initiatives contributing to growth and employment. The 2015 Investment Policy Framework for Sustainable Development includes an action menu promoting investment in sectors relating to the achievement of the Sustainable Development Goals (SDGs). Therefore, this study is aimed at investigating the relationship between sector FDI and sector growth in addition to investigating the effect of sector FDI on sector employment over the period 2000Q1 to 2016Q4 for six of South Africa’s economic sectors. The reason for such a study is based on the premise that developing nations such as South Africa lack sound trade and industrial policies favorable to foreign investors. This then leads to the nation failing to attract higher volumes of FDI which could be used to address structural challenges facing the country. It is therefore important to identify sectors in which FDI has resulted in growth and employment so that when policies are considered, the right FDI is targeted. A comprehensive review of existing theoretical and empirical literature showed that FDI does result in economic growth for developed and developing countries, although FDI crowds out domestic investment in the short run. Literature on the effect of FDI on employment showed diverse effects. Some studies found FDI to increase employment overall, other studies found FDI to increase employment only during periods of restructuring and some studies found FDI to result in job losses. For South African sectors, the present study finds that the financial services sector receives the highest volume of South African FDI, followed by the mining and quarrying sector and the manufacturing, however, FDI in all six sectors under study is associated with increased growth and employment. This finding suggests that the financial services sector has received increased volumes of FDI as a result of financialization of the South African economy. It is this increased FDI in the financial services sector that is directed to income redistribution from the real sector to the finance sector. This study employed econometric techniques and methods of analysis to investigate the relationship between sector FDI and sector growth, and the effect of sector FDI on sector employment. Panel cointegration tests were conducted for all six sectors included in the study to establish if long run equilibrium relationships exist among integrated variables. The Johansen-Fisher panel cointegration test revealed that there is evidence of cointegration in four of the six sectors. Since cointegration was established, the study proceeded to perform the Dumitrescu-Hurlin panel causality analysis and estimate a Panel Vector Error Correction Model (VECM). Results from the causality analysis found a unidirectional causality relationship between FDI and GDP growth, while the panel VECM found FDI to have a significant effect on growth in all sectors. The Seemingly Unrelated Regression (SUR) model employed to investigate the effect of FDI on employment found FDI to have an insignificant effect on employment in all sectors included, although the signs of the coefficients suggest that FDI is associated with increased employment and rising wages is associated with increased productivity growth. Since this study finds that FDI is associated with increased GDP growth in all six sectors under study, policy makers should devise strategies to attract FDI in sectors such as the transportation, storage and communication sector and the electricity, gas and water sector as FDI in these sectors are associated with increased growth however, they receive very low levels of FDI. There are a number of reasons for this, therefore, government institutions and policy makers should investigate the reasons for these low levels of FDI inflows into these sectors so that they can devise further strategies to address these reasons and perhaps attract higher levels of FDI into these sectors. Spillover benefits play a major role in host nations participating in FDI therefore, prior to entering into bilateral treaty agreements, policy makers should ensure that foreign investors are compelled to create jobs, offer training and qualifications etc. through their investments so that some of the SDGs can be achieved. Additionally, this study finds a positive, statistically insignificant relationship between FDI and employment. FDI may not have a significant relationship on employment due to jobless growth and capital-intensive growth rather than labor-intensive growth. Such a situation calls for government intervention. Skills shortage is a rising problem in South Africa; therefore, investors choose to employ advanced technologies rather than people. Under such circumstances, governments are encouraged to invest resources into skills development so that human capital are not completely replaced by technology. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-04
The effect of various substrate pretreatment methods on the enzymatic degradability of a Eucalyptus sp. – a potential feedstock for producing fermentable sugars
- Authors: Thoresen, Mariska
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178580 , vital:42952
- Description: Access restricted until April 2022. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Thoresen, Mariska
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178580 , vital:42952
- Description: Access restricted until April 2022. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
The effects of aspect, directional heating and depth on bedrock temperatures and the potential relationship with thermal fatigue weathering
- Authors: Breytenbach, Izak Johannes
- Date: 2021-04
- Subjects: Weathering -- South Africa -- Karoo , Shields (Geology) -- South Africa -- Karoo , Shields (Geology) -- Thermal properties , Tillite -- South Africa -- Karoo
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177688 , vital:42847 , 10.21504/10962/177688
- Description: Geomorphological weathering processes and their relationship with temperature fluctuations are frequently researched. These research efforts are mostly restricted to surface conditions where soils, loose-lying rocks or rock outcrops are assessed. However, there is a shortcoming in the understanding of the thermal properties in a rock mass, particularly in the upper metres below the surface, as this has not been investigated or researched in any great detail. The research reported here is unique in this regard as it exploited the use of rotary core boreholes in tillite bedrock in the Karoo (Western Cape, South Africa) which were drilled as part of an invasive materials investigation for a proposed new hard rock quarry to supply road stone. Temperature data were captured on a bedrock ridge hosting tillite outcrop with a strong east to west orientation. The site work was done in two separate phases. The initial phase of research saw data being captured for one year on two aspects (i.e. north and south) at a depth of 0.3 m. This was followed by the second (more detailed) phase, where three aspects were assessed (i.e. north, south and a flat crest), but at depths of 0.3 m, 2.0 m and 6.0 m, totalling nine data acquisition points. The second investigation phase gathered data for seven months. Supplementary weather data were also captured for the site. Subsequent data analyses revealed that there is much to learn about the thermal behaviour of bedrock in the upper metres below the surface, and that the temperature properties or thermal regimes are not as simple as often assumed. Temperature differences related to aspect are not only surficial, but are transmitted to underlying bedrock, and notable temperature differences were measurable to a depth of at least 6.0 m. Seasonal temperature fluctuations also have a pronounced effect on the rock mass temperatures and it was proven that deeper parts of the bedrock accumulate and dissipate heat at different (i.e. retarded) rates compared with shallower parts of the rock mass, creating suitable thermal conditions to induce thermal fatigue. Thermal properties were also proven to be non-linear. During analyses, the concept of temperature inversions was proven, whereby one part of the bedrock becomes hotter or cooler relative to another/adjacent part of the bedrock, compared with its earlier temperature state. It was argued that these temperature inversions may exacerbate thermal fatigue. This research proved that aspect (i.e. directional heating) and depth need to be considered when analysing thermal regimes in a rock mass, as these have a distinct influence. The effects which manifest themselves create suitable conditions for thermal fatigue, not only near the surface but also at depth in the bedrock. Lastly, the effects of meteorological conditions on shallow bedrock temperatures were assessed. Preliminary findings suggest that boundary conditions and meteorological processes may indeed affect shallow bedrock temperatures, but only under certain circumstances and not to the same extent as reported in the literature for conditions researched at the surface. Wind temperature relative to the rock temperature, as well as a combination of wind and rain were found to be the most significant factors. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Breytenbach, Izak Johannes
- Date: 2021-04
- Subjects: Weathering -- South Africa -- Karoo , Shields (Geology) -- South Africa -- Karoo , Shields (Geology) -- Thermal properties , Tillite -- South Africa -- Karoo
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177688 , vital:42847 , 10.21504/10962/177688
- Description: Geomorphological weathering processes and their relationship with temperature fluctuations are frequently researched. These research efforts are mostly restricted to surface conditions where soils, loose-lying rocks or rock outcrops are assessed. However, there is a shortcoming in the understanding of the thermal properties in a rock mass, particularly in the upper metres below the surface, as this has not been investigated or researched in any great detail. The research reported here is unique in this regard as it exploited the use of rotary core boreholes in tillite bedrock in the Karoo (Western Cape, South Africa) which were drilled as part of an invasive materials investigation for a proposed new hard rock quarry to supply road stone. Temperature data were captured on a bedrock ridge hosting tillite outcrop with a strong east to west orientation. The site work was done in two separate phases. The initial phase of research saw data being captured for one year on two aspects (i.e. north and south) at a depth of 0.3 m. This was followed by the second (more detailed) phase, where three aspects were assessed (i.e. north, south and a flat crest), but at depths of 0.3 m, 2.0 m and 6.0 m, totalling nine data acquisition points. The second investigation phase gathered data for seven months. Supplementary weather data were also captured for the site. Subsequent data analyses revealed that there is much to learn about the thermal behaviour of bedrock in the upper metres below the surface, and that the temperature properties or thermal regimes are not as simple as often assumed. Temperature differences related to aspect are not only surficial, but are transmitted to underlying bedrock, and notable temperature differences were measurable to a depth of at least 6.0 m. Seasonal temperature fluctuations also have a pronounced effect on the rock mass temperatures and it was proven that deeper parts of the bedrock accumulate and dissipate heat at different (i.e. retarded) rates compared with shallower parts of the rock mass, creating suitable thermal conditions to induce thermal fatigue. Thermal properties were also proven to be non-linear. During analyses, the concept of temperature inversions was proven, whereby one part of the bedrock becomes hotter or cooler relative to another/adjacent part of the bedrock, compared with its earlier temperature state. It was argued that these temperature inversions may exacerbate thermal fatigue. This research proved that aspect (i.e. directional heating) and depth need to be considered when analysing thermal regimes in a rock mass, as these have a distinct influence. The effects which manifest themselves create suitable conditions for thermal fatigue, not only near the surface but also at depth in the bedrock. Lastly, the effects of meteorological conditions on shallow bedrock temperatures were assessed. Preliminary findings suggest that boundary conditions and meteorological processes may indeed affect shallow bedrock temperatures, but only under certain circumstances and not to the same extent as reported in the literature for conditions researched at the surface. Wind temperature relative to the rock temperature, as well as a combination of wind and rain were found to be the most significant factors. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-04
The further development, application and evaluation of a sediment yield model (WQSED) for catchment management in African catchments
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04