Stamping ground: investigating the walkability of Rhodes University students in Makhanda, South Africa
- Authors: Padayachee, Huresha
- Date: 2025-04-02
- Subjects: Walkability , Rhodes University , Campus size South Africa Makhanda , Small cities South Africa Makhanda , College students Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/479197 , vital:78269
- Description: Walkability is an important research topic in the Global South where many people in urban settlements walk because of transport poverty. University students are a subset of the urban population in Makhanda who experience transport poverty and largely rely on walking to navigate the city. The purpose of this study is to measure and spatially analyse walkability and walking patterns in the student community of Makhanda, South Africa. This study has a specific focus on students who reside in the Rhodes University campus, Central Business District (Central), Sunnyside, and Westhill. These specific areas were chosen because, in terms of student residents, these are the most densely populated residential areas in the city, but are also the epicentre of student activity. This research intends to explore the existing walkability within these four study sites through a visual survey using common measures of walkability, digital mapping as well as student perceptions of walkability. The quantitative data collected through visual surveys, digital mapping and participatory mapping will be spatially analysed using GIS (Geographic Information Systems). Results show that walking is the main mode of transportation and students do not have affordable alternatives to walking. The Rhodes University campus is the most walkable area with Central being the second, Westhill being the third, and Sunnyside being the least walkable area. Sidewalk conditions (sidewalk presence, evenness and maintenance) and pedestrian safety and security (pedestrian crossings, crime, security features, lighting, the presence of people, and pedestrian visibility) were rated as the most important walkability factors. Additionally, the more walkable roads are mainly found within the Rhodes University campus and Sunnyside while the less walkable roads are mainly found within Central. Furthermore, the epicentre of student activity is focused on the Rhodes University campus during the week and as the week progresses, the epicentre shifts along with a shift in activity. The Rhodes University campus and Central are where students spent most of their time because the main amenities that student use are found within these areas. This research offers insights into walkability that can be directly applied to urban planning and policy-making. Planners should focus their resources on improving walkability, particularly in sidewalk conditions and pedestrian safety and security. By applying the findings of this research, planners can create more conducive, safer, and comfortable walking environments. , Thesis (MSc) -- Faculty of Science, Geography, 2025
- Full Text:
- Authors: Padayachee, Huresha
- Date: 2025-04-02
- Subjects: Walkability , Rhodes University , Campus size South Africa Makhanda , Small cities South Africa Makhanda , College students Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/479197 , vital:78269
- Description: Walkability is an important research topic in the Global South where many people in urban settlements walk because of transport poverty. University students are a subset of the urban population in Makhanda who experience transport poverty and largely rely on walking to navigate the city. The purpose of this study is to measure and spatially analyse walkability and walking patterns in the student community of Makhanda, South Africa. This study has a specific focus on students who reside in the Rhodes University campus, Central Business District (Central), Sunnyside, and Westhill. These specific areas were chosen because, in terms of student residents, these are the most densely populated residential areas in the city, but are also the epicentre of student activity. This research intends to explore the existing walkability within these four study sites through a visual survey using common measures of walkability, digital mapping as well as student perceptions of walkability. The quantitative data collected through visual surveys, digital mapping and participatory mapping will be spatially analysed using GIS (Geographic Information Systems). Results show that walking is the main mode of transportation and students do not have affordable alternatives to walking. The Rhodes University campus is the most walkable area with Central being the second, Westhill being the third, and Sunnyside being the least walkable area. Sidewalk conditions (sidewalk presence, evenness and maintenance) and pedestrian safety and security (pedestrian crossings, crime, security features, lighting, the presence of people, and pedestrian visibility) were rated as the most important walkability factors. Additionally, the more walkable roads are mainly found within the Rhodes University campus and Sunnyside while the less walkable roads are mainly found within Central. Furthermore, the epicentre of student activity is focused on the Rhodes University campus during the week and as the week progresses, the epicentre shifts along with a shift in activity. The Rhodes University campus and Central are where students spent most of their time because the main amenities that student use are found within these areas. This research offers insights into walkability that can be directly applied to urban planning and policy-making. Planners should focus their resources on improving walkability, particularly in sidewalk conditions and pedestrian safety and security. By applying the findings of this research, planners can create more conducive, safer, and comfortable walking environments. , Thesis (MSc) -- Faculty of Science, Geography, 2025
- Full Text:
An investigation of geospatial technologies in precision agriculture: a case study on a citrus orchard in the Eastern Cape
- Authors: Nish, Declan Mark
- Date: 2024-10-11
- Subjects: Geospatial technology , Agricultural innovations , Precision farming South Africa Eastern Cape , Citrus orchard , Citrus fruit industry , Drone aircraft , Remote sensing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465080 , vital:76571
- Description: Citrus production is an input-intensive farming practice that carries a high cost of production. A multitude of both local and global factors continue to put pressure on farmers to produce enough food for local consumption as well as international exports. Despite these challenges production and exports continue to increase, fighting to meet the growing rise in global demand for citrus (Genis, 2018). Growers are continuously in search of anything that may provide them with the ‘edge’ or an advantage to overcoming some of these challenges (Jupp, 2018). One way in which these issues could be addressed is the use of precision agriculture (PA). Precision agriculture, particularly that of commercial, Unmanned Aerial Vehicle (UAV) based PA, provides growers with solutions to these issues in the form of high quality, near real-time data, and provides access and benefits from technology driven agriculture to growers at all levels (Sishodia et al. 2020). The aim of this research therefore was to investigate the potential of high resolution, multi-spectral UAV, and satellite imagery to help citrus farmers manage their inputs better, save costs and increase their yields in a sustainable manner. Supervised image classification using a support vector machine (SVM) was applied to map and classify a citrus farm in the Eastern Cape. The approach aided the identification of Phytophthora spp in the section of interest and implies that remotely sensed data can be used to detect changes in citrus health. Guidelines for applying geospatial technologies at farm level were developed to provide a framework for enabling growers to enhance data driven farm management strategies. , Thesis (MSc) -- Faculty of Science, Geography, 2024
- Full Text:
- Authors: Nish, Declan Mark
- Date: 2024-10-11
- Subjects: Geospatial technology , Agricultural innovations , Precision farming South Africa Eastern Cape , Citrus orchard , Citrus fruit industry , Drone aircraft , Remote sensing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465080 , vital:76571
- Description: Citrus production is an input-intensive farming practice that carries a high cost of production. A multitude of both local and global factors continue to put pressure on farmers to produce enough food for local consumption as well as international exports. Despite these challenges production and exports continue to increase, fighting to meet the growing rise in global demand for citrus (Genis, 2018). Growers are continuously in search of anything that may provide them with the ‘edge’ or an advantage to overcoming some of these challenges (Jupp, 2018). One way in which these issues could be addressed is the use of precision agriculture (PA). Precision agriculture, particularly that of commercial, Unmanned Aerial Vehicle (UAV) based PA, provides growers with solutions to these issues in the form of high quality, near real-time data, and provides access and benefits from technology driven agriculture to growers at all levels (Sishodia et al. 2020). The aim of this research therefore was to investigate the potential of high resolution, multi-spectral UAV, and satellite imagery to help citrus farmers manage their inputs better, save costs and increase their yields in a sustainable manner. Supervised image classification using a support vector machine (SVM) was applied to map and classify a citrus farm in the Eastern Cape. The approach aided the identification of Phytophthora spp in the section of interest and implies that remotely sensed data can be used to detect changes in citrus health. Guidelines for applying geospatial technologies at farm level were developed to provide a framework for enabling growers to enhance data driven farm management strategies. , Thesis (MSc) -- Faculty of Science, Geography, 2024
- Full Text:
Aspects of the sustainability of the wild honeybush industry
- Authors: McGregor, Gillian Kathleen
- Date: 2024-10-11
- Subjects: Cyclopia intermedia , Renewable natural resources South Africa , Sustainability , Local ecological knowledge , Harvesting
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464266 , vital:76493 , DOI 10.21504/10962/464266
- Description: Honeybush products are uniquely South African, derived from plants of the fynbos genus, Cyclopia. Cyclopia intermedia is the most widespread species, distributed across 11 496 km2 of the Cape Fold Mountains, and provided the bulk of supply for the industry until 2022. While the industry is small, it is a locally significant industry affecting the livelihoods of harvesters, farmers and processors in the greater Langkloof region of the Eastern and Western Cape provinces of South Africa. The industry has evolved from a cottage one, to a commercial scale, and concerns have been raised over the sustainability of the wild resource specifically, and the industry in general. The research aimed to improve our understanding of aspects of the sustainability of the wild honeybush industry. A mixed methods design was adopted, which allowed for the inclusion of data collection approaches and analysis which tell a richer story than one with a singular modus. Four objectives were identified, which entailed: (i) mapping the resource to establish the distribution range of C. intermedia; (ii) recording of local ecological knowledge (LEK) and traditional ecological knowledge (TEK) around best practice harvesting; (iii) assessing the sustainability of harvest enterprise types through analysis of yield history and harvester loads; (iv) identifying differences between harvested and unharvested C. intermedia populations. Mapping of the resource drew on a variety of existing data sources, field mapping, GIS-based analysis, species distribution modelling and expert mapping to create a comprehensive and accurate map of the species distribution. The species is estimated to occupy a distribution range of 11 496 km2, 49% of which occurs in formally protected areas. Based on local scale mapping by experts, 100km2 is estimated to be in use for wild harvesting in the production area of the Langkloof. Information on best practice harvesting was collected through in-depth interviews with harvesters, harvest managers, processors and farmers (in the field at harvest events) and through questionnaire surveys and focus group discussions at a honeybush stakeholder workshop. In combination with harvest event surveys at which harvester practice was observed and recorded, and surveys were conducted of the harvest yield and of plants in the harvested population, the information was used to produce the first formal account of best practice for sustainable harvesting of wild honeybush. To assess the sustainability of harvest enterprises and associated harvester livelihoods, harvester managers were interviewed to create profiles of typical harvesting enterprises based on their practices and harvest yield histories. Of the three harvest enterprises considered, two showed sustained yields over time, while those of a large contract type enterprise were less sustainable with declining yields on three out of six farms. From a statistical analysis of the records it was found that the most effective team size was 10 or less harvesters in terms of livelihood sustainability. They could earn a fair livelihood (ZAR67 680.00) per annum, based on a 94 kg load per daily harvest event, sold to the processor at ZAR 5.00, for nine months of the year, working a four-day week. For a team to operate sustainably, it was found that it should consist of experienced harvesters harvesting conservatively, at intervals of at least four years, and be responsive to local environmental conditions. Detailed field surveys of C. intermedia plants at 38 sites representing harvested and unharvested populations were carried out to understand the impact of harvesting on the plants. A statistical analysis of the plant's dimensions related to the physical environment, fire and harvest history using generalised linear models revealed that while unharvested plants were slightly larger, only crown diameter and stem counts were significantly so. Seedlings were noticeably scarce at all sites, including recently burnt sites. A significant finding of the research was that in a fecundity survey, unharvested plants produced significantly more pods. The impact of this is unknown, but it has implications for management and the sustainable use of wild resources in the long term. Further understanding of the impact of harvesting came from surveys of cultivated stands of C. intermedia (different ages and harvest histories, but all harvested at three-year intervals) and surveys of a wild population, which was subjected to unregulated harvesting. For the cultivated stand: after 12 years, plants declined in all measured dimensions, while in the wild population, 45% of the plants died over a seven-year period. The surveys proved that a three-year interval or frequent, unregulated harvest is unsustainable. The research was used to produce the wild harvesting guidelines, which have become the accepted standard for the industry. It has demonstrated that under the right circumstances, harvesting of the wild C. intermedia resource is broadly sustainable. However, there needs to be informed management of the use of the resource in terms of harvest team types and their protocols, particularly with regard to harvest intervals and possible interventions to improve seed production to achieve sustainable use of the resource in social, economic and ecological terms. , Thesis (PhD) -- Faculty of Science, Geography, 2024
- Full Text:
- Authors: McGregor, Gillian Kathleen
- Date: 2024-10-11
- Subjects: Cyclopia intermedia , Renewable natural resources South Africa , Sustainability , Local ecological knowledge , Harvesting
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464266 , vital:76493 , DOI 10.21504/10962/464266
- Description: Honeybush products are uniquely South African, derived from plants of the fynbos genus, Cyclopia. Cyclopia intermedia is the most widespread species, distributed across 11 496 km2 of the Cape Fold Mountains, and provided the bulk of supply for the industry until 2022. While the industry is small, it is a locally significant industry affecting the livelihoods of harvesters, farmers and processors in the greater Langkloof region of the Eastern and Western Cape provinces of South Africa. The industry has evolved from a cottage one, to a commercial scale, and concerns have been raised over the sustainability of the wild resource specifically, and the industry in general. The research aimed to improve our understanding of aspects of the sustainability of the wild honeybush industry. A mixed methods design was adopted, which allowed for the inclusion of data collection approaches and analysis which tell a richer story than one with a singular modus. Four objectives were identified, which entailed: (i) mapping the resource to establish the distribution range of C. intermedia; (ii) recording of local ecological knowledge (LEK) and traditional ecological knowledge (TEK) around best practice harvesting; (iii) assessing the sustainability of harvest enterprise types through analysis of yield history and harvester loads; (iv) identifying differences between harvested and unharvested C. intermedia populations. Mapping of the resource drew on a variety of existing data sources, field mapping, GIS-based analysis, species distribution modelling and expert mapping to create a comprehensive and accurate map of the species distribution. The species is estimated to occupy a distribution range of 11 496 km2, 49% of which occurs in formally protected areas. Based on local scale mapping by experts, 100km2 is estimated to be in use for wild harvesting in the production area of the Langkloof. Information on best practice harvesting was collected through in-depth interviews with harvesters, harvest managers, processors and farmers (in the field at harvest events) and through questionnaire surveys and focus group discussions at a honeybush stakeholder workshop. In combination with harvest event surveys at which harvester practice was observed and recorded, and surveys were conducted of the harvest yield and of plants in the harvested population, the information was used to produce the first formal account of best practice for sustainable harvesting of wild honeybush. To assess the sustainability of harvest enterprises and associated harvester livelihoods, harvester managers were interviewed to create profiles of typical harvesting enterprises based on their practices and harvest yield histories. Of the three harvest enterprises considered, two showed sustained yields over time, while those of a large contract type enterprise were less sustainable with declining yields on three out of six farms. From a statistical analysis of the records it was found that the most effective team size was 10 or less harvesters in terms of livelihood sustainability. They could earn a fair livelihood (ZAR67 680.00) per annum, based on a 94 kg load per daily harvest event, sold to the processor at ZAR 5.00, for nine months of the year, working a four-day week. For a team to operate sustainably, it was found that it should consist of experienced harvesters harvesting conservatively, at intervals of at least four years, and be responsive to local environmental conditions. Detailed field surveys of C. intermedia plants at 38 sites representing harvested and unharvested populations were carried out to understand the impact of harvesting on the plants. A statistical analysis of the plant's dimensions related to the physical environment, fire and harvest history using generalised linear models revealed that while unharvested plants were slightly larger, only crown diameter and stem counts were significantly so. Seedlings were noticeably scarce at all sites, including recently burnt sites. A significant finding of the research was that in a fecundity survey, unharvested plants produced significantly more pods. The impact of this is unknown, but it has implications for management and the sustainable use of wild resources in the long term. Further understanding of the impact of harvesting came from surveys of cultivated stands of C. intermedia (different ages and harvest histories, but all harvested at three-year intervals) and surveys of a wild population, which was subjected to unregulated harvesting. For the cultivated stand: after 12 years, plants declined in all measured dimensions, while in the wild population, 45% of the plants died over a seven-year period. The surveys proved that a three-year interval or frequent, unregulated harvest is unsustainable. The research was used to produce the wild harvesting guidelines, which have become the accepted standard for the industry. It has demonstrated that under the right circumstances, harvesting of the wild C. intermedia resource is broadly sustainable. However, there needs to be informed management of the use of the resource in terms of harvest team types and their protocols, particularly with regard to harvest intervals and possible interventions to improve seed production to achieve sustainable use of the resource in social, economic and ecological terms. , Thesis (PhD) -- Faculty of Science, Geography, 2024
- Full Text:
Sediment and associated phosphorus dynamics in meandering floodplain wetlands in the Tsitsa River catchment
- Authors: Schlegel, Philippa Kirsten
- Date: 2024-10-11
- Subjects: Sediments (Geology) , Phosphorus , Sedimentation and deposition , Ecosystem services Law and legislation South Africa , Arid regions South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466860 , vital:76793 , DOI https://doi.org/10.21504/10962/466860
- Description: A key function of floodplain wetlands systems is their ability to remove and store sediments and associated particulates (such as nutrients, organic carbon, and contaminants) from water, thus improving water quality for downstream ecosystems and water users. Increases in sediment and nutrient inputs to drainage networks pose a serious challenge to integrated resource management. These issues can be partly mitigated through natural buffering solutions along drainage networks, such as preserving essential wetland systems like floodplains. However, their trapping efficiency and storage timescales are uncertain. Although a large body of international knowledge and literature has advanced our understanding of river-floodplain systems and the ecosystem services that they provide, the factors determining their likelihood and effectiveness in supplying those regulatory ecosystem services have not been extensively and scientifically tested in floodplain systems in South Africa. This research aimed to describe and quantify the regulatory ecosystem services related to sediment and phosphorus buffering dynamics of two meandering floodplain systems in the Eastern Cape, South Africa. The study examined the geomorphology, sedimentology, and historical rates of sediment and associated phosphorus accumulation and release in the two floodplain systems. These systems varied in their morphometric features, size, catchment location, and predominant land use, providing a diverse range of characteristics. A comparative analysis was conducted between the two systems to understand the influence of local and catchment-scale factors. Time-averaged suspended sediment samples from the two wetlands were used to compare suspended sediment and associated total phosphorous fluxes over annual scales. Although both floodplains were net depositional during the study period, contemporary suspended sediment mass balance calculations suggested that the relatively larger Minnehaha floodplain system (~1.5 km²) situated in a significantly smaller catchment (~40 km²) had notably higher sediment and associated phosphorus trapping efficiencies of 44 % and 49 % respectively, compared to 16 % and 8 % for the relatively small Gatberg floodplain system (~0.3 km2) situated in a much larger catchment (~135 km²). This variability is attributed to the interaction between annual rainfall regimes, sediment supply, sediment composition, relative wetland size to catchment area and wetland geomorphic character. To test the hypothesis that the suspended sediments and associated total phosphorus were retained by the adjacent floodplain system and to determine which parts of the two floodplains were most effective for retaining suspended sediments and phosphorus, concurrent measurements of sediment accretion were made at 6 sites in different geomorphic features in each of the floodplains. This was achieved using Cesium-137 and Lead-210 (Hereinafter referred to as ¹³⁷Cs and ²¹⁰Pb) dating techniques. In-field observations suggested that all geomorphic units are still active and are frequently inundated during overbank flood flows. The average overbank sediment deposition and total phosphorus accumulation rates were 9376.9 g-sediment m¯² yr¯¹, 0.8 g-TP m¯² yr¯¹ for the Gatberg floodplain and 11802.8 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain. Deposition rates were temporally and spatially highly variable and dependent on the sediment supply, microtopographic relief, sinuosity, distance from the channel, the mode of inundation, and the extent of retention pondage. Overall, high average deposition rates were associated closest to the channel within the proximal floodplain zone (9712.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Gatberg floodplain; 13541.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain) where the highest D₅₀ particle sizes (25.4 μm for the Gatberg and 32.8 μm for the Minnehaha) and percentage sand fractions (15 % and 21 %, respectively) were found. This may reflect the coarse nature of the sediment and the frequent connectivity to the channel, suggesting rapid accumulation is linked to a larger particle size which was deposited more readily in this zone. In the Gatberg system, the backswamp zone had one of the highest sedimentation rates and second highest phosphorus accumulation rates (13806.8 g-sediment m¯² yr¯¹, 0.9 g-TP m¯² yr¯¹). This was attributed to the additional coarse sediment inputs from the uncapped gravel forestry road that runs adjacent to the floodplain margin. In contrast, the backswamp zone within the Minnehaha River floodplain system had the lowest sedimentation rates (2005.9 g-sediment m¯² yr¯¹, 0.1 g-TP m¯² yr¯¹, which is what would be expected for the zone furthest away from the channel. In both floodplains, oxbows were important fine-sediment and phosphorus retention features (7126.0 g-sediment m¯² yr¯¹, 0.6 g-TP m¯² yr¯¹ for the Gatberg floodplain; 10101.0 g-sediment m¯² yr¯¹, 1.1 g-TP m¯² yr¯¹). Phosphorus distribution patterns were mainly attributed to variations in organic matter content and iron concentrations in fine-grained sediment deposits, while particle size distributions were less important. Using a mass balance approach the trapping efficiencies of the two floodplain systems were estimated. The average trapping efficiency for the Gatberg River floodplain accounts for 16 % of the suspended sediment yield (1317.5 tonnes-sediment yr¯¹) and 8 % of the suspended sediment-associated total phosphorus yield (0.093 tonnes-TP yr¯¹). Deposition on the Minnehaha floodplain accounts for an average of 44 % (1073.6 tonnes-sediment yr¯¹) and 49 % of the suspended sediment-associated total phosphorus yield (0.098 tonnes-TP yr¯¹). Within the Gatberg and Minnehaha River floodplain systems, the sediment sinks (oxbow and backswamp geomorphic zones) accounted for 13 % and 6 % (1070.6 tonnes-sediment yr¯¹ and 0.069 tonnes-TP yr¯¹); and 28 % and 33 % (683.2 tonnes-sediment yr¯¹ and 0.066 tonnes-TP yr¯¹), respectively, of the mean proportion of the total sediment and associated phosphorus yield. The zone of potential exchange (the proximal floodplain geomorphic zone) within the Gatberg floodplain system was calculated to trap 3 % (247.1 tonnes-yr¯¹) of the mean proportion of the total sediment yield and 2 % (0.023-tonnes yr¯¹) of the mean proportion of the total associated-phosphorus yield. Within the Minnehaha floodplain, this zone was estimated to trap 16 % (390.4 tonnes-sediment yr¯¹ and 0.032 tonnes-TP yr¯¹) of the mean proportion of both the total sediment and associated total phosphorus yield. These results indicate the importance of the distal floodplain reaches and oxbows as sediment and phosphorus storage hotspots. While floodplains mainly result from the accumulation of sediment, they're often modified and altered by erosion processes. Channel erosion and avulsions (e.g. meander bend cutoff events) are natural dynamic processes and form two of the principal processes of meandering river migration. During two wet seasons, both Gatberg and Minnehaha River floodplain areas experienced a mix of deposition and erosion, with slightly higher erosion observed in the Gatberg River reach. Channel bed scouring was prevalent in most cross-sections, suggesting limited sediment accumulation within the main channel beds. Volumetric estimates of sediment loss from meander migration were calculated by analysing cross-sectional data from 2019 and 2021 surveys to determine median and maximum eroded volumes, which were then converted to mass and scaled to tonnes per year for each river's eroded meander bends. The eroded sediment volumes were estimated as 520 tonnes yr¯¹ for the Gatberg and 360 tonnes yr¯¹ for the Minnehaha. The time sequence analysis using historical aerial images (between 1958, 1966, 1993, and 2015) revealed a few channel planform changes due to meander bend cutoff events in both river reaches. These events influence river morphology, increasing local channel slope, reducing sinuosity, and limiting floodplain access while impacting sediment and phosphorus flux. In the Gatberg system, changes in land use, such as increased road density from commercial forestry activities, likely drove channel straightening to accommodate higher sediment and bed loads. In the Minnehaha system, agricultural practices and livestock tracks likely increased sediment loads and hillslope-channel connectivity, driving channel changes. The results from the geochronology of two nested oxbows on the Gatberg floodplain estimated lateral migration rates of ~0.03 m yr¯¹. The floodplain reworking rates of the Gatberg River floodplain are low compared to other systems in humid regions around the world, although, the Gatberg system compares well with migration rates of rivers in dryland regions. This study highlights the potential for floodplains undergoing regular flooding to be effective natural buffers along the sediment and phosphorus cascade in dryland landscapes. It enhances our comprehension of how sediment accumulates over time on floodplains within South African river systems, shedding light on both spatial and temporal patterns. These insights can contribute to better methodologies for evaluating the services provided by floodplain wetlands. These results can inform management decisions by offering a deeper understanding and allowing for the quantification of the cost-benefit of floodplain restoration and preservation actions in South Africa. , Thesis (PhD) -- Faculty of Science, Faculty of Science, Geography, 2024
- Full Text:
- Authors: Schlegel, Philippa Kirsten
- Date: 2024-10-11
- Subjects: Sediments (Geology) , Phosphorus , Sedimentation and deposition , Ecosystem services Law and legislation South Africa , Arid regions South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466860 , vital:76793 , DOI https://doi.org/10.21504/10962/466860
- Description: A key function of floodplain wetlands systems is their ability to remove and store sediments and associated particulates (such as nutrients, organic carbon, and contaminants) from water, thus improving water quality for downstream ecosystems and water users. Increases in sediment and nutrient inputs to drainage networks pose a serious challenge to integrated resource management. These issues can be partly mitigated through natural buffering solutions along drainage networks, such as preserving essential wetland systems like floodplains. However, their trapping efficiency and storage timescales are uncertain. Although a large body of international knowledge and literature has advanced our understanding of river-floodplain systems and the ecosystem services that they provide, the factors determining their likelihood and effectiveness in supplying those regulatory ecosystem services have not been extensively and scientifically tested in floodplain systems in South Africa. This research aimed to describe and quantify the regulatory ecosystem services related to sediment and phosphorus buffering dynamics of two meandering floodplain systems in the Eastern Cape, South Africa. The study examined the geomorphology, sedimentology, and historical rates of sediment and associated phosphorus accumulation and release in the two floodplain systems. These systems varied in their morphometric features, size, catchment location, and predominant land use, providing a diverse range of characteristics. A comparative analysis was conducted between the two systems to understand the influence of local and catchment-scale factors. Time-averaged suspended sediment samples from the two wetlands were used to compare suspended sediment and associated total phosphorous fluxes over annual scales. Although both floodplains were net depositional during the study period, contemporary suspended sediment mass balance calculations suggested that the relatively larger Minnehaha floodplain system (~1.5 km²) situated in a significantly smaller catchment (~40 km²) had notably higher sediment and associated phosphorus trapping efficiencies of 44 % and 49 % respectively, compared to 16 % and 8 % for the relatively small Gatberg floodplain system (~0.3 km2) situated in a much larger catchment (~135 km²). This variability is attributed to the interaction between annual rainfall regimes, sediment supply, sediment composition, relative wetland size to catchment area and wetland geomorphic character. To test the hypothesis that the suspended sediments and associated total phosphorus were retained by the adjacent floodplain system and to determine which parts of the two floodplains were most effective for retaining suspended sediments and phosphorus, concurrent measurements of sediment accretion were made at 6 sites in different geomorphic features in each of the floodplains. This was achieved using Cesium-137 and Lead-210 (Hereinafter referred to as ¹³⁷Cs and ²¹⁰Pb) dating techniques. In-field observations suggested that all geomorphic units are still active and are frequently inundated during overbank flood flows. The average overbank sediment deposition and total phosphorus accumulation rates were 9376.9 g-sediment m¯² yr¯¹, 0.8 g-TP m¯² yr¯¹ for the Gatberg floodplain and 11802.8 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain. Deposition rates were temporally and spatially highly variable and dependent on the sediment supply, microtopographic relief, sinuosity, distance from the channel, the mode of inundation, and the extent of retention pondage. Overall, high average deposition rates were associated closest to the channel within the proximal floodplain zone (9712.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Gatberg floodplain; 13541.1 g-sediment m¯² yr¯¹, 1.0 g-TP m¯² yr¯¹ for the Minnehaha floodplain) where the highest D₅₀ particle sizes (25.4 μm for the Gatberg and 32.8 μm for the Minnehaha) and percentage sand fractions (15 % and 21 %, respectively) were found. This may reflect the coarse nature of the sediment and the frequent connectivity to the channel, suggesting rapid accumulation is linked to a larger particle size which was deposited more readily in this zone. In the Gatberg system, the backswamp zone had one of the highest sedimentation rates and second highest phosphorus accumulation rates (13806.8 g-sediment m¯² yr¯¹, 0.9 g-TP m¯² yr¯¹). This was attributed to the additional coarse sediment inputs from the uncapped gravel forestry road that runs adjacent to the floodplain margin. In contrast, the backswamp zone within the Minnehaha River floodplain system had the lowest sedimentation rates (2005.9 g-sediment m¯² yr¯¹, 0.1 g-TP m¯² yr¯¹, which is what would be expected for the zone furthest away from the channel. In both floodplains, oxbows were important fine-sediment and phosphorus retention features (7126.0 g-sediment m¯² yr¯¹, 0.6 g-TP m¯² yr¯¹ for the Gatberg floodplain; 10101.0 g-sediment m¯² yr¯¹, 1.1 g-TP m¯² yr¯¹). Phosphorus distribution patterns were mainly attributed to variations in organic matter content and iron concentrations in fine-grained sediment deposits, while particle size distributions were less important. Using a mass balance approach the trapping efficiencies of the two floodplain systems were estimated. The average trapping efficiency for the Gatberg River floodplain accounts for 16 % of the suspended sediment yield (1317.5 tonnes-sediment yr¯¹) and 8 % of the suspended sediment-associated total phosphorus yield (0.093 tonnes-TP yr¯¹). Deposition on the Minnehaha floodplain accounts for an average of 44 % (1073.6 tonnes-sediment yr¯¹) and 49 % of the suspended sediment-associated total phosphorus yield (0.098 tonnes-TP yr¯¹). Within the Gatberg and Minnehaha River floodplain systems, the sediment sinks (oxbow and backswamp geomorphic zones) accounted for 13 % and 6 % (1070.6 tonnes-sediment yr¯¹ and 0.069 tonnes-TP yr¯¹); and 28 % and 33 % (683.2 tonnes-sediment yr¯¹ and 0.066 tonnes-TP yr¯¹), respectively, of the mean proportion of the total sediment and associated phosphorus yield. The zone of potential exchange (the proximal floodplain geomorphic zone) within the Gatberg floodplain system was calculated to trap 3 % (247.1 tonnes-yr¯¹) of the mean proportion of the total sediment yield and 2 % (0.023-tonnes yr¯¹) of the mean proportion of the total associated-phosphorus yield. Within the Minnehaha floodplain, this zone was estimated to trap 16 % (390.4 tonnes-sediment yr¯¹ and 0.032 tonnes-TP yr¯¹) of the mean proportion of both the total sediment and associated total phosphorus yield. These results indicate the importance of the distal floodplain reaches and oxbows as sediment and phosphorus storage hotspots. While floodplains mainly result from the accumulation of sediment, they're often modified and altered by erosion processes. Channel erosion and avulsions (e.g. meander bend cutoff events) are natural dynamic processes and form two of the principal processes of meandering river migration. During two wet seasons, both Gatberg and Minnehaha River floodplain areas experienced a mix of deposition and erosion, with slightly higher erosion observed in the Gatberg River reach. Channel bed scouring was prevalent in most cross-sections, suggesting limited sediment accumulation within the main channel beds. Volumetric estimates of sediment loss from meander migration were calculated by analysing cross-sectional data from 2019 and 2021 surveys to determine median and maximum eroded volumes, which were then converted to mass and scaled to tonnes per year for each river's eroded meander bends. The eroded sediment volumes were estimated as 520 tonnes yr¯¹ for the Gatberg and 360 tonnes yr¯¹ for the Minnehaha. The time sequence analysis using historical aerial images (between 1958, 1966, 1993, and 2015) revealed a few channel planform changes due to meander bend cutoff events in both river reaches. These events influence river morphology, increasing local channel slope, reducing sinuosity, and limiting floodplain access while impacting sediment and phosphorus flux. In the Gatberg system, changes in land use, such as increased road density from commercial forestry activities, likely drove channel straightening to accommodate higher sediment and bed loads. In the Minnehaha system, agricultural practices and livestock tracks likely increased sediment loads and hillslope-channel connectivity, driving channel changes. The results from the geochronology of two nested oxbows on the Gatberg floodplain estimated lateral migration rates of ~0.03 m yr¯¹. The floodplain reworking rates of the Gatberg River floodplain are low compared to other systems in humid regions around the world, although, the Gatberg system compares well with migration rates of rivers in dryland regions. This study highlights the potential for floodplains undergoing regular flooding to be effective natural buffers along the sediment and phosphorus cascade in dryland landscapes. It enhances our comprehension of how sediment accumulates over time on floodplains within South African river systems, shedding light on both spatial and temporal patterns. These insights can contribute to better methodologies for evaluating the services provided by floodplain wetlands. These results can inform management decisions by offering a deeper understanding and allowing for the quantification of the cost-benefit of floodplain restoration and preservation actions in South Africa. , Thesis (PhD) -- Faculty of Science, Faculty of Science, Geography, 2024
- Full Text:
Investigating changes in pineapple (Ananas comosus) cultivation in the Eastern Cape, South Africa, from 1984 to 2020
- Authors: Marriner, Paul Joseph
- Date: 2024-04-04
- Subjects: Pineapple South Africa Eastern Cape , Land use and land cover , Land cover , Remote sensing , Image classification
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435354 , vital:73150
- Description: Land use and land cover change (LULCC) resulting from agricultural activities have significantly impacted landscape transformation and fragmentation. The Albany Thicket Biome in the Eastern Cape Province stands out for its exceptional vegetation diversity and remarkable rates of species endemism. However, the relationship between agricultural activities and the Albany Thicket Biome has not received sufficient attention in the literature, creating a significant gap in understanding the extent of landscape transformation and the vegetation's recovery rate. This study aims to address this gap by utilising remote sensing technologies to investigate the LULCC specifically caused by pineapple cultivation in the Lower Albany area between 1984 and 2020. Analysis, using remotely sensed imagery and spatial analytical tools, provide accurate identification of pineapple fields and enable monitoring of their effects on LULCC dynamics across a wide spatial and temporal scale. Complementary field assessments examined the impacts of pineapple cultivation on land use and cover. Twelve image classifiers were tested to identify the most appropriate technique for mapping pineapple fields, and the Supervised Pixel-based Support Vector Machine (SVM) image classifier was found to be the most suitable. Utilising Landsat 4, 5, 7, and 8 satellite imagery, 27 land cover maps were created, spanning the period from 1984 to 2020. Additionally, field verification was conducted at 59 randomly generated sites to validate the findings. Spatial analysis of the data revealed that the pineapple industry in the study area has expanded by 733 hectares since 1984. Significant land use changes were observed, including converting land to wildlife ranches, grazing areas, and alternative agricultural practices. The land cover analysis identified the emergence of pioneer species in former pineapple fields, suggesting the potential for Albany Thicket regrowth if appropriately managed. This research contributes to a better understanding of the impacts of pineapple cultivation on the Albany Thicket Biome and provides valuable insights for land use planning and monitoring efforts. A comprehensive assessment of LULCC dynamics can be achieved by utilising remote sensing techniques, informing sustainable land management practices in the study area and beyond. , Thesis (MSc) -- Faculty of Science, Geography, 2024
- Full Text:
- Authors: Marriner, Paul Joseph
- Date: 2024-04-04
- Subjects: Pineapple South Africa Eastern Cape , Land use and land cover , Land cover , Remote sensing , Image classification
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435354 , vital:73150
- Description: Land use and land cover change (LULCC) resulting from agricultural activities have significantly impacted landscape transformation and fragmentation. The Albany Thicket Biome in the Eastern Cape Province stands out for its exceptional vegetation diversity and remarkable rates of species endemism. However, the relationship between agricultural activities and the Albany Thicket Biome has not received sufficient attention in the literature, creating a significant gap in understanding the extent of landscape transformation and the vegetation's recovery rate. This study aims to address this gap by utilising remote sensing technologies to investigate the LULCC specifically caused by pineapple cultivation in the Lower Albany area between 1984 and 2020. Analysis, using remotely sensed imagery and spatial analytical tools, provide accurate identification of pineapple fields and enable monitoring of their effects on LULCC dynamics across a wide spatial and temporal scale. Complementary field assessments examined the impacts of pineapple cultivation on land use and cover. Twelve image classifiers were tested to identify the most appropriate technique for mapping pineapple fields, and the Supervised Pixel-based Support Vector Machine (SVM) image classifier was found to be the most suitable. Utilising Landsat 4, 5, 7, and 8 satellite imagery, 27 land cover maps were created, spanning the period from 1984 to 2020. Additionally, field verification was conducted at 59 randomly generated sites to validate the findings. Spatial analysis of the data revealed that the pineapple industry in the study area has expanded by 733 hectares since 1984. Significant land use changes were observed, including converting land to wildlife ranches, grazing areas, and alternative agricultural practices. The land cover analysis identified the emergence of pioneer species in former pineapple fields, suggesting the potential for Albany Thicket regrowth if appropriately managed. This research contributes to a better understanding of the impacts of pineapple cultivation on the Albany Thicket Biome and provides valuable insights for land use planning and monitoring efforts. A comprehensive assessment of LULCC dynamics can be achieved by utilising remote sensing techniques, informing sustainable land management practices in the study area and beyond. , Thesis (MSc) -- Faculty of Science, Geography, 2024
- Full Text:
High-resolution hydraulic modelling as an approach to planning rehabilitation interventions in unchanneled valley-bottom palmiet wetlands: a case study of the Kromme River
- Authors: Langner, Wiebke
- Date: 2023-10-13
- Subjects: Hydraulic models , Prionium serratum , Wetland conservation South Africa Kromme River (Eastern Cape) , LiDAR , Fluvial geomorphology
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424610 , vital:72168
- Description: This study employs high-resolution hydraulic modelling techniques to inform the planning of rehabilitation interventions in unchanneled valley-bottom palmiet wetlands, using the upper Kromme River wetlands as a case study. It investigates the impact of geomorphic processes on the morphology of the valley, how changes in valley morphology affect the flow characteristics (velocity, stream power, depth) of the river, and how these changes affect the geomorphic dynamics of the wetlands. An aerial LiDAR survey was conducted for a 23km-long reach of the upper Kromme River where the wetlands are situated. A high-resolution (5 m) DTM was created from the LiDAR data to examine the valley morphology. Focusing on three major wetland basins, the relationship between valley morphology and geomorphic processes was examined using high-resolution imagery that accompanied the LiDAR survey and Google Satellite imagery. The hydraulic modelling software HEC-RAS was used to investigate the spatial variation in velocity, stream power, and water depth down the surveyed length of the river. The model outputs provide insight into the effect of valley morphology on flow characteristics. The river appears to have a graded longitudinal profile, such that there is a systematic reduction in slope down its length. Water flowing down the river works, through the processes of erosion and deposition, to control the longitudinal slope, channel planform, and geometry to create a valley with a gentle longitudinal slope (approximately 1%) and a broad, near-horizontal valley-bottom in the mountainous landscape of the Cape Fold Mountains. The overall form of the Kromme River valley and wetlands is primarily a consequence of repeated cycles of cutting and filling. Tributary alluvial fans control the initiation of gully erosion in the wetlands, but their effect is diminished in a downstream direction. Despite a 10-fold increase in discharge down the 23km length of river for a given flood magnitude, there is no significant increase in flow velocity, stream power, or depth in a downstream direction. Consequently, the kinetic energy of the water in the lower wetland basin is surprisingly low. These conditions favour the establishment of palmiet. Flows in eroded reaches are much higher than in non-eroded reaches where discharge is spread across a broad valley bottom. In terms of palmiet establishment and regeneration, this means that areas dominated by depositional processes are best suited to the establishment of palmiet. Based on this information, optimal sites to trial new wetland rehabilitation strategies that employ palmiet were selected. This work supports the importance of understanding the role of geomorphology in wetland structure and dynamics when approaching wetland rehabilitation and is likely to be more sympathetic to natural processes than current interventions. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
- Authors: Langner, Wiebke
- Date: 2023-10-13
- Subjects: Hydraulic models , Prionium serratum , Wetland conservation South Africa Kromme River (Eastern Cape) , LiDAR , Fluvial geomorphology
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424610 , vital:72168
- Description: This study employs high-resolution hydraulic modelling techniques to inform the planning of rehabilitation interventions in unchanneled valley-bottom palmiet wetlands, using the upper Kromme River wetlands as a case study. It investigates the impact of geomorphic processes on the morphology of the valley, how changes in valley morphology affect the flow characteristics (velocity, stream power, depth) of the river, and how these changes affect the geomorphic dynamics of the wetlands. An aerial LiDAR survey was conducted for a 23km-long reach of the upper Kromme River where the wetlands are situated. A high-resolution (5 m) DTM was created from the LiDAR data to examine the valley morphology. Focusing on three major wetland basins, the relationship between valley morphology and geomorphic processes was examined using high-resolution imagery that accompanied the LiDAR survey and Google Satellite imagery. The hydraulic modelling software HEC-RAS was used to investigate the spatial variation in velocity, stream power, and water depth down the surveyed length of the river. The model outputs provide insight into the effect of valley morphology on flow characteristics. The river appears to have a graded longitudinal profile, such that there is a systematic reduction in slope down its length. Water flowing down the river works, through the processes of erosion and deposition, to control the longitudinal slope, channel planform, and geometry to create a valley with a gentle longitudinal slope (approximately 1%) and a broad, near-horizontal valley-bottom in the mountainous landscape of the Cape Fold Mountains. The overall form of the Kromme River valley and wetlands is primarily a consequence of repeated cycles of cutting and filling. Tributary alluvial fans control the initiation of gully erosion in the wetlands, but their effect is diminished in a downstream direction. Despite a 10-fold increase in discharge down the 23km length of river for a given flood magnitude, there is no significant increase in flow velocity, stream power, or depth in a downstream direction. Consequently, the kinetic energy of the water in the lower wetland basin is surprisingly low. These conditions favour the establishment of palmiet. Flows in eroded reaches are much higher than in non-eroded reaches where discharge is spread across a broad valley bottom. In terms of palmiet establishment and regeneration, this means that areas dominated by depositional processes are best suited to the establishment of palmiet. Based on this information, optimal sites to trial new wetland rehabilitation strategies that employ palmiet were selected. This work supports the importance of understanding the role of geomorphology in wetland structure and dynamics when approaching wetland rehabilitation and is likely to be more sympathetic to natural processes than current interventions. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
Maintaining the façade: the disconnect between policy and practice in heritage resources management in Makhanda, South Africa
- Authors: Dlongolo, Zandile Nombulelo
- Date: 2023-10-13
- Subjects: Heritage management , Urban development , Cultural property South Africa Makhanda , Cultural resources management , Heritage tourism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424576 , vital:72165
- Description: Cultural heritage is globally acknowledged as having the potential to contribute to positive economic, environmental, political, and social impacts (Graham, 2002). In the South African context, cultural heritage management is rooted in colonial and apartheid narratives that mark a large part of the country's history. Post-apartheid transformation processes have driven new approaches to managing heritage to represent the shared collective narrative of a democratic South Africa. This transformation includes the formation of the three-tiered South African heritage management system by the National Heritage Resources Agency (NHRA) in 1999 and a rethinking of what heritage constitutes and whose heritage matters. Despite the extensive cultural heritage resources in the country, literature concerning the management of these assets in the context of the urban environment and urban planning and management is limited (Donaldson, 2001; Donaldson et al., 2013; Buchanan & Donaldson, 2021; Kruger & Donaldson, 2021). This research explores the built environment heritage resources in Makhanda (formerly Grahamstown) in the Eastern Cape province. Makhanda possesses a rich and varied cultural heritage landscape, including over 70 Provincial Heritage Resources in the form of built environment heritage. The case study provides a perfect laboratory for investigating the various threats and opportunities in the local context that severely affect heritage management. The research used a mixed-method approach to generate data. Primary data were collected through a field survey of built environment heritage resources, semi-structured interviews, and focus groups. Secondary data sources comprised government policy documents, by-laws, reports, research papers and newspaper articles. In the localised context, findings illustrated several challenges affecting local heritage management, centring mainly on the balance between heritage resource management and overall urban management. Findings identified challenges included a poor acknowledgement of the nuances in local history, questions on the effectiveness of legislation, governance and management issues, conflicting demands for social services and urban development, and building maintenance. Heritage resources are acknowledged as a potential tool to meet the local community's needs, and opportunities for developing the heritage sector were also identified. These suggestions include information sharing and cooperation between the municipality, community and various role players, community education, tourism product development, institutional development through skills development, the incorporation of intangible heritage, and the acknowledgement of more inclusive forms of cultural heritage. Overall, the findings indicate that the disconnection in heritage management, urban management practices, and municipal dysfunction in Makhanda threatens the built environment heritage and the local sense of place. The study argues that for local heritage management to succeed, there needs to be a balanced approach to heritage management and urban management through improvements in stakeholder relationships, governance, institutional capacity, knowledge sharing and community involvement in decision-making processes. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
- Authors: Dlongolo, Zandile Nombulelo
- Date: 2023-10-13
- Subjects: Heritage management , Urban development , Cultural property South Africa Makhanda , Cultural resources management , Heritage tourism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424576 , vital:72165
- Description: Cultural heritage is globally acknowledged as having the potential to contribute to positive economic, environmental, political, and social impacts (Graham, 2002). In the South African context, cultural heritage management is rooted in colonial and apartheid narratives that mark a large part of the country's history. Post-apartheid transformation processes have driven new approaches to managing heritage to represent the shared collective narrative of a democratic South Africa. This transformation includes the formation of the three-tiered South African heritage management system by the National Heritage Resources Agency (NHRA) in 1999 and a rethinking of what heritage constitutes and whose heritage matters. Despite the extensive cultural heritage resources in the country, literature concerning the management of these assets in the context of the urban environment and urban planning and management is limited (Donaldson, 2001; Donaldson et al., 2013; Buchanan & Donaldson, 2021; Kruger & Donaldson, 2021). This research explores the built environment heritage resources in Makhanda (formerly Grahamstown) in the Eastern Cape province. Makhanda possesses a rich and varied cultural heritage landscape, including over 70 Provincial Heritage Resources in the form of built environment heritage. The case study provides a perfect laboratory for investigating the various threats and opportunities in the local context that severely affect heritage management. The research used a mixed-method approach to generate data. Primary data were collected through a field survey of built environment heritage resources, semi-structured interviews, and focus groups. Secondary data sources comprised government policy documents, by-laws, reports, research papers and newspaper articles. In the localised context, findings illustrated several challenges affecting local heritage management, centring mainly on the balance between heritage resource management and overall urban management. Findings identified challenges included a poor acknowledgement of the nuances in local history, questions on the effectiveness of legislation, governance and management issues, conflicting demands for social services and urban development, and building maintenance. Heritage resources are acknowledged as a potential tool to meet the local community's needs, and opportunities for developing the heritage sector were also identified. These suggestions include information sharing and cooperation between the municipality, community and various role players, community education, tourism product development, institutional development through skills development, the incorporation of intangible heritage, and the acknowledgement of more inclusive forms of cultural heritage. Overall, the findings indicate that the disconnection in heritage management, urban management practices, and municipal dysfunction in Makhanda threatens the built environment heritage and the local sense of place. The study argues that for local heritage management to succeed, there needs to be a balanced approach to heritage management and urban management through improvements in stakeholder relationships, governance, institutional capacity, knowledge sharing and community involvement in decision-making processes. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
Relating vegetation distribution to cycles of erosion and deposition in the Kromme River wetlands
- Authors: Jarvis, Samuel Cameron
- Date: 2023-10-13
- Subjects: Biogeomorphology South Africa Kromme Estuary (Eastern Cape) , Earth observation , Remote sensing , Niche construction , Wetland ecology , Geomorphology , Ecological succession , Optical radar , Prionium serratum
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424582 , vital:72166
- Description: The role of geomorphic disturbance has been increasingly recognized as fundamental in the creation and functioning of wetlands. This is true of the Kromme River wetland which has been formed through repeated cycles of erosion and deposition. However, the response – and influence – of wetland plants to these sorts of disturbance has not been investigated. This study sought to fill this knowledge gap by classifying vegetation communities over a range of hydrological and geomorphic disturbance regimes that have happened over the last few decades, and relating those vegetation communities to environmental factors. The study identified seven vegetation communities based on their species composition and abundance, which were related to geomorphic disturbance events. A conceptual model that accounts for vegetation distribution in the Kromme wetland was developed. Soil saturation was the most important factor explaining vegetation community distribution, which, in turn, is influenced by cycles of erosion and deposition. Following an erosional event on the valley floor, Prionium serratum dominated wetland is converted to a number of other vegetation communities. On the floodplain surface adjacent to the eroded gully, the Prionium serratum dominated wetland is transformed over time to Cynodon dactylon and Sporobolus fimbriatus communities. Prionium serratum clumps immediately adjacent to the recently incised gullies are able to persist, having sufficient access to water. Within the newly formed gullies, Juncus lomatophyllus colonizes the gully beds flooded to a shallow depth, Miscanthus capensis colonizes the gully bars and Setaria incrassata colonizes the exposed gully banks. Localised depositional features close to the thalweg in the gully are colonized by Prionium serratum seedlings and vegetative propagules. These plants represent the regenerating phase of Prionium serratum wetland, which also colonizes depositional floodouts downstream of the newly-formed gully. The Stenotaphrum secundatum community dominates drier, more elevated areas of the floodout. Over time, as the gully fills, Prionium serratum expands beyond the gully onto the valley floor, to replace the floodplain communities Cynodon dactylon and Sporobolus fimbriatus. Over time, Prionium serratum is thought to colonize the valley floor as the gully fills, stabilising it and promoting diffuse flow. Many restoration efforts in damaged palmiet wetlands have been focused on the preservation of intact palmiet communities upstream of erosional headcuts, with limited understanding of vegetation dynamics associated with the cut-and-fill cycles that naturally occur in these wetlands. Understanding the regeneration of Prionium serratum following erosional events is thus important for wetland restoration, as it should focus more attention on promoting palmiet restoration on depositional floodouts downstream of eroded gullies. A secondary aim of this study was to explore the possibility of mapping palmiet communities in Kromme River wetland using remote sensing techniques. Using a combination of ground-truthed data from this and previous studies in the Kromme River wetland, together with raster layers derived from a LiDAR survey, an overlay analysis was developed to effectively map the distribution of the Prionium serratum dominated community. The overlay was created using a machine learning library in RStudios known as Rpart. The results found that the model were 91% effective in classifying the distribution of the Prionium serratum community. A secondary finding was that the inclusion of a Relative Elevation Model in the overlay analysis allowed for the identification of Prionium serratum communities vulnerable to degradation following previous geomorphic disturbance events and those Prionium serratum communities that are likely to persist following a geomorphic disturbance event. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
- Authors: Jarvis, Samuel Cameron
- Date: 2023-10-13
- Subjects: Biogeomorphology South Africa Kromme Estuary (Eastern Cape) , Earth observation , Remote sensing , Niche construction , Wetland ecology , Geomorphology , Ecological succession , Optical radar , Prionium serratum
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424582 , vital:72166
- Description: The role of geomorphic disturbance has been increasingly recognized as fundamental in the creation and functioning of wetlands. This is true of the Kromme River wetland which has been formed through repeated cycles of erosion and deposition. However, the response – and influence – of wetland plants to these sorts of disturbance has not been investigated. This study sought to fill this knowledge gap by classifying vegetation communities over a range of hydrological and geomorphic disturbance regimes that have happened over the last few decades, and relating those vegetation communities to environmental factors. The study identified seven vegetation communities based on their species composition and abundance, which were related to geomorphic disturbance events. A conceptual model that accounts for vegetation distribution in the Kromme wetland was developed. Soil saturation was the most important factor explaining vegetation community distribution, which, in turn, is influenced by cycles of erosion and deposition. Following an erosional event on the valley floor, Prionium serratum dominated wetland is converted to a number of other vegetation communities. On the floodplain surface adjacent to the eroded gully, the Prionium serratum dominated wetland is transformed over time to Cynodon dactylon and Sporobolus fimbriatus communities. Prionium serratum clumps immediately adjacent to the recently incised gullies are able to persist, having sufficient access to water. Within the newly formed gullies, Juncus lomatophyllus colonizes the gully beds flooded to a shallow depth, Miscanthus capensis colonizes the gully bars and Setaria incrassata colonizes the exposed gully banks. Localised depositional features close to the thalweg in the gully are colonized by Prionium serratum seedlings and vegetative propagules. These plants represent the regenerating phase of Prionium serratum wetland, which also colonizes depositional floodouts downstream of the newly-formed gully. The Stenotaphrum secundatum community dominates drier, more elevated areas of the floodout. Over time, as the gully fills, Prionium serratum expands beyond the gully onto the valley floor, to replace the floodplain communities Cynodon dactylon and Sporobolus fimbriatus. Over time, Prionium serratum is thought to colonize the valley floor as the gully fills, stabilising it and promoting diffuse flow. Many restoration efforts in damaged palmiet wetlands have been focused on the preservation of intact palmiet communities upstream of erosional headcuts, with limited understanding of vegetation dynamics associated with the cut-and-fill cycles that naturally occur in these wetlands. Understanding the regeneration of Prionium serratum following erosional events is thus important for wetland restoration, as it should focus more attention on promoting palmiet restoration on depositional floodouts downstream of eroded gullies. A secondary aim of this study was to explore the possibility of mapping palmiet communities in Kromme River wetland using remote sensing techniques. Using a combination of ground-truthed data from this and previous studies in the Kromme River wetland, together with raster layers derived from a LiDAR survey, an overlay analysis was developed to effectively map the distribution of the Prionium serratum dominated community. The overlay was created using a machine learning library in RStudios known as Rpart. The results found that the model were 91% effective in classifying the distribution of the Prionium serratum community. A secondary finding was that the inclusion of a Relative Elevation Model in the overlay analysis allowed for the identification of Prionium serratum communities vulnerable to degradation following previous geomorphic disturbance events and those Prionium serratum communities that are likely to persist following a geomorphic disturbance event. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
Remote sensing as a monitoring solution for water hyacinth (Pontederia crassipes) in the context of the biological control programme at Hartbeespoort Dam
- Authors: Kinsler, David Louis
- Date: 2023-10-13
- Subjects: Remote sensing , Water hyacinth South Africa Hartbeespoort , Aquatic weeds Biological control South Africa Hartbeespoort , Megamelus scutellaris , Eutrophication
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424599 , vital:72167
- Description: Water hyacinth (Pontederia crassipes (C.Mart.) Solms (Pontederiaceae)) is a significant aquatic weed both globally and in South Africa. Despite notable success with biological control of other invasive macrophytes, the plant remains as a problematic weed in many aquatic systems in South Africa, particularly due to the eutrophic status of many of its water systems, as well as the plant’s tolerance to cooler climatic conditions than most of its existing biological control agents. Hartbeespoort Dam, located about 30 kilometres west of Pretoria, South Africa, has been infamously infested with water hyacinth for decades, which impacts the important socioeconomic utility of the dam and functioning of natural ecological processes in the system. The dam has a long history of efforts to control water hyacinth, which include widespread herbicidal spray, mechanical removal and classical biological control programmes since the early 1990s - mostly with limited or short-lived success. However, after the introduction of a new, cold-tolerant biological control agent, Megamelus scutellaris Berg (Hemiptera: Delphacidae) in 2018 with an inundative release strategy, the water hyacinth dropped significantly from a maximum cover of about 45 percent (819 hectares) down to less than two percent (40 hectares) over a three-month period (November 2019 – January 2020). This was significant, as it marked the first successful biological control of water hyacinth in a eutrophic, temperate system in South Africa. However, due to the scale of Hartbeespoort Dam (1820 hectares) and the high spatiotemporal variation of the floating mats across time and space, quantifying and monitoring these rapid changes has proved difficult. In response to this problem, this thesis proposed a remote sensing solution to address the need for accurate, timely and readily accessible monitoring data of the water hyacinth population on the dam. Leveraging the temporally frequent (< 5 days revisit time) Sentinel-2 multispectral satellite data, as well as the powerful cloud-computing resources of Google Earth Engine, this thesis developed and deployed a relatively simple and robust index-based decision tree classification method to demonstrate the value of these technologies as an effective monitoring and analysis tool for monitoring large macrophyte infestations. To this end, several challenges had to be overcome in order to produce easily accessible data that was accurate and reliable. For example, due to the size of the Sentinel-2 Level-1C image dataset from August 2015 to March 2021 (n = 654), an automated process of filtering out clouded images was required. Additionally, the co-presence of algal and cyanobacterial blooms necessitated the development of a novel index, coined the Algae Resistant Macrophyte Index (ARMI), to deal with the challenges of accurate macrophyte detection. The high spatiotemporal variability of the floating mats meant that a typical, location-based confusion matrix as a means of assessing the accuracy of the decision tree classifier required a different approach which compared the total classified areas with higher resolution images. This thesis aims to demonstrate the utility of remote sensing tools to provide effective monitoring information to managers, researchers and other stakeholders. There is scope to expand to more areas in South Africa and beyond and may prove an invaluable tool to augment and support on-going and future macrophyte monitoring programmes. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
- Authors: Kinsler, David Louis
- Date: 2023-10-13
- Subjects: Remote sensing , Water hyacinth South Africa Hartbeespoort , Aquatic weeds Biological control South Africa Hartbeespoort , Megamelus scutellaris , Eutrophication
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424599 , vital:72167
- Description: Water hyacinth (Pontederia crassipes (C.Mart.) Solms (Pontederiaceae)) is a significant aquatic weed both globally and in South Africa. Despite notable success with biological control of other invasive macrophytes, the plant remains as a problematic weed in many aquatic systems in South Africa, particularly due to the eutrophic status of many of its water systems, as well as the plant’s tolerance to cooler climatic conditions than most of its existing biological control agents. Hartbeespoort Dam, located about 30 kilometres west of Pretoria, South Africa, has been infamously infested with water hyacinth for decades, which impacts the important socioeconomic utility of the dam and functioning of natural ecological processes in the system. The dam has a long history of efforts to control water hyacinth, which include widespread herbicidal spray, mechanical removal and classical biological control programmes since the early 1990s - mostly with limited or short-lived success. However, after the introduction of a new, cold-tolerant biological control agent, Megamelus scutellaris Berg (Hemiptera: Delphacidae) in 2018 with an inundative release strategy, the water hyacinth dropped significantly from a maximum cover of about 45 percent (819 hectares) down to less than two percent (40 hectares) over a three-month period (November 2019 – January 2020). This was significant, as it marked the first successful biological control of water hyacinth in a eutrophic, temperate system in South Africa. However, due to the scale of Hartbeespoort Dam (1820 hectares) and the high spatiotemporal variation of the floating mats across time and space, quantifying and monitoring these rapid changes has proved difficult. In response to this problem, this thesis proposed a remote sensing solution to address the need for accurate, timely and readily accessible monitoring data of the water hyacinth population on the dam. Leveraging the temporally frequent (< 5 days revisit time) Sentinel-2 multispectral satellite data, as well as the powerful cloud-computing resources of Google Earth Engine, this thesis developed and deployed a relatively simple and robust index-based decision tree classification method to demonstrate the value of these technologies as an effective monitoring and analysis tool for monitoring large macrophyte infestations. To this end, several challenges had to be overcome in order to produce easily accessible data that was accurate and reliable. For example, due to the size of the Sentinel-2 Level-1C image dataset from August 2015 to March 2021 (n = 654), an automated process of filtering out clouded images was required. Additionally, the co-presence of algal and cyanobacterial blooms necessitated the development of a novel index, coined the Algae Resistant Macrophyte Index (ARMI), to deal with the challenges of accurate macrophyte detection. The high spatiotemporal variability of the floating mats meant that a typical, location-based confusion matrix as a means of assessing the accuracy of the decision tree classifier required a different approach which compared the total classified areas with higher resolution images. This thesis aims to demonstrate the utility of remote sensing tools to provide effective monitoring information to managers, researchers and other stakeholders. There is scope to expand to more areas in South Africa and beyond and may prove an invaluable tool to augment and support on-going and future macrophyte monitoring programmes. , Thesis (MSc) -- Faculty of Science, Geography, 2023
- Full Text:
The regeneration of palmiet (prionium serratum) following hydrogeomorphic disturbance: a case study of the Kromme River wetland
- Authors: Van Eck, Caydon Daniël
- Date: 2022-10-14
- Subjects: Biogeomorphology South Africa Kromme Estuary (Eastern Cape) , Wetland ecology , Prionium serratum Regeneration , Fluvial geomorphology , River channels
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/365555 , vital:65759
- Description: The Kromme River wetland in the Eastern Cape of South Africa occupies a broad valley (up to 350 m wide) with a gentle longitudinal slope of less than 2 % that has been formed by cut-and-fill cycles that are initiated by trunk-tributary interactions. These hydrogeomorphic disturbance events trigger gully erosion and generate sediments, the coarse fraction of which is deposited less than 2 km downstream, leading to depositional floodout features that fill gullies headwards. This process has been occurring at intervals for at least 10 000 years, and as such pre-dates the introduction of European farming practices in the area. Plants that regenerate by colonising these features are thought to have evolved adaptions necessary to colonise intermittently produced bare sandy sediments. This study aimed to examine the regeneration ecology of palmiet (Prionium serratum), the dominant vegetation community within these cut-and-fill wetlands, by relating its regeneration characteristics to environmental factors in a reach of the Kromme River wetland that has experienced a recent hydrogeomorphic disturbance event (approximately 10 years before the commencement of this study). Palmiet was found to be regenerating on sedimentary deposits on beds of gullies and on depositional bars on the margins of gully beds. The large depositional floodout downstream of a large gully also favoured palmiet regeneration, where it was found to be regenerating along not only the active channel, but also along old abandoned flow paths and sometimes areas well elevated above the channel. The geomorphic features that favoured palmiet regeneration were characterised by coarse-grained sediments (mean particle size approximately 310 μm) with low organic matter content (0.61 %), a low depth to the water table and low elevation above the thalweg (mean depth to water table is approximately 0.6 m), and a relatively close distance to the thalweg (< 10 m). This understanding of palmiet’s regeneration characteristics was viewed in relation to existing literature on undisturbed palmiet wetland plant communities and its reported contribution to conditions that favour wetland formation through gully filling, which allowed for the creation of a conceptual model of palmiet regeneration, colonisation and long-term persistence. This model was based on the Fluvial Biogeomorphic Succession concept. It suggests that palmiet’s interaction with the hydrogeomorphic environment throughout the different stages of its life cycle results in self-organising biogeomorphic landforms. Over hundreds of years, the reciprocal interactions between palmiet, sediments and water, fills gullies and restores valley bottoms, ultimately leading to the formation of a wetland landform. It is further proposed that through continued accretion, the geomorphic wetland landscape becomes more and more disconnected from the hydrogeomorphic dynamics of the fluvial system, such that the prevailing conditions begin to favour fynbos establishment, which may outcompete palmiet. , Thesis (MSc) -- Faculty of Science, Geography, 2022
- Full Text:
- Authors: Van Eck, Caydon Daniël
- Date: 2022-10-14
- Subjects: Biogeomorphology South Africa Kromme Estuary (Eastern Cape) , Wetland ecology , Prionium serratum Regeneration , Fluvial geomorphology , River channels
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/365555 , vital:65759
- Description: The Kromme River wetland in the Eastern Cape of South Africa occupies a broad valley (up to 350 m wide) with a gentle longitudinal slope of less than 2 % that has been formed by cut-and-fill cycles that are initiated by trunk-tributary interactions. These hydrogeomorphic disturbance events trigger gully erosion and generate sediments, the coarse fraction of which is deposited less than 2 km downstream, leading to depositional floodout features that fill gullies headwards. This process has been occurring at intervals for at least 10 000 years, and as such pre-dates the introduction of European farming practices in the area. Plants that regenerate by colonising these features are thought to have evolved adaptions necessary to colonise intermittently produced bare sandy sediments. This study aimed to examine the regeneration ecology of palmiet (Prionium serratum), the dominant vegetation community within these cut-and-fill wetlands, by relating its regeneration characteristics to environmental factors in a reach of the Kromme River wetland that has experienced a recent hydrogeomorphic disturbance event (approximately 10 years before the commencement of this study). Palmiet was found to be regenerating on sedimentary deposits on beds of gullies and on depositional bars on the margins of gully beds. The large depositional floodout downstream of a large gully also favoured palmiet regeneration, where it was found to be regenerating along not only the active channel, but also along old abandoned flow paths and sometimes areas well elevated above the channel. The geomorphic features that favoured palmiet regeneration were characterised by coarse-grained sediments (mean particle size approximately 310 μm) with low organic matter content (0.61 %), a low depth to the water table and low elevation above the thalweg (mean depth to water table is approximately 0.6 m), and a relatively close distance to the thalweg (< 10 m). This understanding of palmiet’s regeneration characteristics was viewed in relation to existing literature on undisturbed palmiet wetland plant communities and its reported contribution to conditions that favour wetland formation through gully filling, which allowed for the creation of a conceptual model of palmiet regeneration, colonisation and long-term persistence. This model was based on the Fluvial Biogeomorphic Succession concept. It suggests that palmiet’s interaction with the hydrogeomorphic environment throughout the different stages of its life cycle results in self-organising biogeomorphic landforms. Over hundreds of years, the reciprocal interactions between palmiet, sediments and water, fills gullies and restores valley bottoms, ultimately leading to the formation of a wetland landform. It is further proposed that through continued accretion, the geomorphic wetland landscape becomes more and more disconnected from the hydrogeomorphic dynamics of the fluvial system, such that the prevailing conditions begin to favour fynbos establishment, which may outcompete palmiet. , Thesis (MSc) -- Faculty of Science, Geography, 2022
- Full Text:
Wild Honeybush (Cyclopia intermedia) augmentation
- Authors: Michau, Paul-Luc
- Date: 2022-04-06
- Subjects: Herbal teas South Africa Joubertina , Tea trade South Africa Joubertina , Legumes Harvesting South Africa Joubertina , Legumes Planting South Africa Joubertina , Sustainable development South Africa Joubertina , Economic development Environmental aspects South Africa Joubertina , Natural resources Management South Africa Joubertina , Wild Honeybush (Cyclopia intermedia)
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232635 , vital:50009
- Description: Honeybush (Cyclopia spp.) is an endemic legume to the fynbos region of South Africa, and certain species of the genus are used to make health tonics. There are growing international markets for such products and, currently, wild populations of the species Cyclopia intermedia are disproportionately relied upon to support this increase. Due to the sensitivity and ecological complexity of the resource, serious concerns about sustainability and regulation have arisen. The social landscape of the resource is equally as complex, and solutions for alleviating pressure on wild populations, such as reducing or banning harvesting, and switching to commercial cultivation are untenable in every case. A possible option, which has been used in the wildflower industry, is to augment (increase) wild populations by planting seeds or seedlings directly into the veld. The main focus of this research was to explore the viability of using augmentation to boost wild populations of C. intermedia through field trials. In support of this broad aim, research objectives addressed understanding the ecological habitat conditions of the species, quantifying the economic potential of augmentation, characterizing wild populations and conducting seed germination tests. GIS methods were used to locate sites most representative of natural conditions on different post-fire aged veld on a farm in the Kouga mountains. The study characterized habitat conditions by collecting soil and vegetation samples at plots where honeybush was present and absent within close proximity. Vegetation diversity was only slightly higher in presence plots, and no clear pattern between absence and presence plots was observed for soil properties. However, post-fire site age did significantly influence certain nutrient levels. The augmentation trial results indicate that seedlings have a much higher survival rate than seeds on average. Survival success varied unpredictably between plots where wild honeybush was already present and adjacent plots where it was absent. Post-fire site age influenced seedling growth and seed survival positively with the newly burnt plots showing the best growth rates overall. The cost-benefit analysis reveals that seeds are a better option as they require low-cost inputs and carry less risk, unlike seedlings which may have higher survival but are more expensive. The study recommends using trials to assess survival before choosing an option. Out of five natural populations of honeybush that were assessed only one showed seedling recruitment and three young plants were found between two of the other sites. Growth characteristics of populations showed expected variability based on site conditions and disturbance history. Growth appears to be rapid in the first-year post disturbance, thereafter slowing down. Average stem numbers and basal circumference increased concurrently for both harvested and unharvested populations. Due to the influence of natural conditions such as slope aspect and soil properties on plant morphology, it is best to compare harvested and unharvested individuals from the same site and preferably within close proximity to minimize such differences. Using seed sourced from the same parent population is critical to preserving genetic integrity and little is understood about germination characteristics from wild C. intermedia populations. The study tested germination rates between green and brown seed and alternative collection methods. When comparisons were done within farms on two occasions collection and seed colour did have a significant influence. Overall, the influence of which farm the seeds were collected from appeared to play the biggest role in determining germination. , Thesis (MSc) -- Faculty of Science, Geography, 2022
- Full Text:
- Authors: Michau, Paul-Luc
- Date: 2022-04-06
- Subjects: Herbal teas South Africa Joubertina , Tea trade South Africa Joubertina , Legumes Harvesting South Africa Joubertina , Legumes Planting South Africa Joubertina , Sustainable development South Africa Joubertina , Economic development Environmental aspects South Africa Joubertina , Natural resources Management South Africa Joubertina , Wild Honeybush (Cyclopia intermedia)
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232635 , vital:50009
- Description: Honeybush (Cyclopia spp.) is an endemic legume to the fynbos region of South Africa, and certain species of the genus are used to make health tonics. There are growing international markets for such products and, currently, wild populations of the species Cyclopia intermedia are disproportionately relied upon to support this increase. Due to the sensitivity and ecological complexity of the resource, serious concerns about sustainability and regulation have arisen. The social landscape of the resource is equally as complex, and solutions for alleviating pressure on wild populations, such as reducing or banning harvesting, and switching to commercial cultivation are untenable in every case. A possible option, which has been used in the wildflower industry, is to augment (increase) wild populations by planting seeds or seedlings directly into the veld. The main focus of this research was to explore the viability of using augmentation to boost wild populations of C. intermedia through field trials. In support of this broad aim, research objectives addressed understanding the ecological habitat conditions of the species, quantifying the economic potential of augmentation, characterizing wild populations and conducting seed germination tests. GIS methods were used to locate sites most representative of natural conditions on different post-fire aged veld on a farm in the Kouga mountains. The study characterized habitat conditions by collecting soil and vegetation samples at plots where honeybush was present and absent within close proximity. Vegetation diversity was only slightly higher in presence plots, and no clear pattern between absence and presence plots was observed for soil properties. However, post-fire site age did significantly influence certain nutrient levels. The augmentation trial results indicate that seedlings have a much higher survival rate than seeds on average. Survival success varied unpredictably between plots where wild honeybush was already present and adjacent plots where it was absent. Post-fire site age influenced seedling growth and seed survival positively with the newly burnt plots showing the best growth rates overall. The cost-benefit analysis reveals that seeds are a better option as they require low-cost inputs and carry less risk, unlike seedlings which may have higher survival but are more expensive. The study recommends using trials to assess survival before choosing an option. Out of five natural populations of honeybush that were assessed only one showed seedling recruitment and three young plants were found between two of the other sites. Growth characteristics of populations showed expected variability based on site conditions and disturbance history. Growth appears to be rapid in the first-year post disturbance, thereafter slowing down. Average stem numbers and basal circumference increased concurrently for both harvested and unharvested populations. Due to the influence of natural conditions such as slope aspect and soil properties on plant morphology, it is best to compare harvested and unharvested individuals from the same site and preferably within close proximity to minimize such differences. Using seed sourced from the same parent population is critical to preserving genetic integrity and little is understood about germination characteristics from wild C. intermedia populations. The study tested germination rates between green and brown seed and alternative collection methods. When comparisons were done within farms on two occasions collection and seed colour did have a significant influence. Overall, the influence of which farm the seeds were collected from appeared to play the biggest role in determining germination. , Thesis (MSc) -- Faculty of Science, Geography, 2022
- Full Text:
Application of environmental magnetism to trace sediment sources contributing to Kruger National Park reservoirs
- Authors: Miller, Jordan Katherine
- Date: 2021-10-29
- Subjects: Geomagnetism South Africa Kruger National Park , Sediments (Geology) South Africa Kruger National Park , Sedimentation and deposition South Africa Kruger National Park , Petrology South Africa Kruger National Park , Sediments (Geology) Magnetic properties South Africa Kruger National Park
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192842 , vital:45269 , 10.21504/10962/192842
- Description: Sediment source fingerprinting using environmental magnetism has successfully differentiated between sediment sources in different regions of South Africa. The method was applied in the natural landscape of the Kruger National Park to trace sediment sources delivered to four reservoirs (Hartbeesfontein, Marheya, Nhlanganzwani, Silolweni) whose contributing catchments were underlain by a range of igneous, metamorphic, and sedimentary rocks. This research attempted to evaluate the impact of vegetation, lithology, and particle size controls on the ability of magnetic signatures to discriminate between lithology-defined potential sources. Potential source samples were collected from each lithology present in all catchments, except for the Lugmag catchment where the lithology was uniform, but the vegetation type varied significantly between woodland and grassland. One sediment core was taken in each of the four catchment reservoirs where there was more than one lithology present in order to unmix and apportion contributing sediment sources. Sampling time in the field was often restricted to short periods, dependent on anti-poaching activities and movement of free-roaming wildlife across the Park. This occasionally led to the sub-optimal collection of enough source samples to capture source signature variability. Mineral magnetic parameters were unable to discriminate between vegetation-defined sediment sources in the Lugmag catchment (homogenous underlying lithology) but were able to discriminate between lithology-defined sediment sources (to varying degrees) in the other four catchments. The contributions of each lithology-defined sediment source were estimated using a straightforward statistical protocol frequently used in published literature that included a Mann-Whitney U or Kruskal-Wallis H test, mass conservation test, discriminant function analysis, and an (un)mixing model. A contribution from each lithology source to reservoir sediment was estimated. Connectivity was a significant factor in understanding erosion in each of the catchments. Both longitudinal (e.g., drainage density) and lateral connectivity (e.g., floodplain - river) were important. Travel distance of eroded sediment to reservoirs was also an essential element in two of the four catchments. There are no defined floodplains, so channel bank soils are very similar to the catchment soils. Therefore, channel bank storage potential would be similar to the storage potential within the catchment. Vegetation played a crucial role in protecting soils, by reducing ii erosion potential as well as trapping and storing sediment, thereby interrupting lateral connectivity. Underlying geology and soils are determining factors of vegetation type and density. A published study estimated catchment area-specific sediment yields for different KNP catchments, including the Hartbeesfontein, Marheya, Nhlanganzwani and Silolweni catchments. The published data was used in combination with the (un)mixing model source contribution estimates of this thesis to determine specific sediment yields by lithology, i.e., for each catchment source. The polymodal particle size characteristics of the sample material led to an investigation into particle size controls on the ability of magnetic signatures to discriminate between potential sources. Due to time constraints, only the Hartbeesfontein and Marheya catchments were tested for grain size differences. For each catchment, one bulk sample was created for each lithology source. This bulk sample was divided into 10 subsamples. The samples were then fractionated into four particle size fraction groups: coarse (250 – 500 μm), medium (125 – 250 μm), fine (63 – 125 μm), and very fine (<63 μm). Reservoir samples were also bulked to create 10 down-core samples for each reservoir, and the samples were also fractionated into the four fraction groups. The same statistical protocol was applied to the fractionated samples and contribution estimates were obtained by lithology for each particle size fraction group. The goodness of fit and uncertainty of the (un)mixing model varied in each catchment, with the two measures of accuracy often showing an inverse relationship. The fractionated modelling estimated the same primary source in the two catchments as in the unfractionated modelling. However, additional information on the secondary and tertiary sources was obtained. Connectivity remained a significant factor in interpreting the results of the fractionated analysis. Specific sediment yields were estimated for each catchment source per particle size fraction group. These sediment yields provided a deeper understanding of sediment transport through a catchment and which particle size groups are most important in catchment erosion. An original contribution to research was made by estimating source contribution estimates for the four reservoirs, quantifying sediment yields for each catchment lithology and then for each catchment lithology by particle size. Mineral magnetic tracing of the catchments was applied for the first time in this region of South Africa. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: Miller, Jordan Katherine
- Date: 2021-10-29
- Subjects: Geomagnetism South Africa Kruger National Park , Sediments (Geology) South Africa Kruger National Park , Sedimentation and deposition South Africa Kruger National Park , Petrology South Africa Kruger National Park , Sediments (Geology) Magnetic properties South Africa Kruger National Park
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/192842 , vital:45269 , 10.21504/10962/192842
- Description: Sediment source fingerprinting using environmental magnetism has successfully differentiated between sediment sources in different regions of South Africa. The method was applied in the natural landscape of the Kruger National Park to trace sediment sources delivered to four reservoirs (Hartbeesfontein, Marheya, Nhlanganzwani, Silolweni) whose contributing catchments were underlain by a range of igneous, metamorphic, and sedimentary rocks. This research attempted to evaluate the impact of vegetation, lithology, and particle size controls on the ability of magnetic signatures to discriminate between lithology-defined potential sources. Potential source samples were collected from each lithology present in all catchments, except for the Lugmag catchment where the lithology was uniform, but the vegetation type varied significantly between woodland and grassland. One sediment core was taken in each of the four catchment reservoirs where there was more than one lithology present in order to unmix and apportion contributing sediment sources. Sampling time in the field was often restricted to short periods, dependent on anti-poaching activities and movement of free-roaming wildlife across the Park. This occasionally led to the sub-optimal collection of enough source samples to capture source signature variability. Mineral magnetic parameters were unable to discriminate between vegetation-defined sediment sources in the Lugmag catchment (homogenous underlying lithology) but were able to discriminate between lithology-defined sediment sources (to varying degrees) in the other four catchments. The contributions of each lithology-defined sediment source were estimated using a straightforward statistical protocol frequently used in published literature that included a Mann-Whitney U or Kruskal-Wallis H test, mass conservation test, discriminant function analysis, and an (un)mixing model. A contribution from each lithology source to reservoir sediment was estimated. Connectivity was a significant factor in understanding erosion in each of the catchments. Both longitudinal (e.g., drainage density) and lateral connectivity (e.g., floodplain - river) were important. Travel distance of eroded sediment to reservoirs was also an essential element in two of the four catchments. There are no defined floodplains, so channel bank soils are very similar to the catchment soils. Therefore, channel bank storage potential would be similar to the storage potential within the catchment. Vegetation played a crucial role in protecting soils, by reducing ii erosion potential as well as trapping and storing sediment, thereby interrupting lateral connectivity. Underlying geology and soils are determining factors of vegetation type and density. A published study estimated catchment area-specific sediment yields for different KNP catchments, including the Hartbeesfontein, Marheya, Nhlanganzwani and Silolweni catchments. The published data was used in combination with the (un)mixing model source contribution estimates of this thesis to determine specific sediment yields by lithology, i.e., for each catchment source. The polymodal particle size characteristics of the sample material led to an investigation into particle size controls on the ability of magnetic signatures to discriminate between potential sources. Due to time constraints, only the Hartbeesfontein and Marheya catchments were tested for grain size differences. For each catchment, one bulk sample was created for each lithology source. This bulk sample was divided into 10 subsamples. The samples were then fractionated into four particle size fraction groups: coarse (250 – 500 μm), medium (125 – 250 μm), fine (63 – 125 μm), and very fine (<63 μm). Reservoir samples were also bulked to create 10 down-core samples for each reservoir, and the samples were also fractionated into the four fraction groups. The same statistical protocol was applied to the fractionated samples and contribution estimates were obtained by lithology for each particle size fraction group. The goodness of fit and uncertainty of the (un)mixing model varied in each catchment, with the two measures of accuracy often showing an inverse relationship. The fractionated modelling estimated the same primary source in the two catchments as in the unfractionated modelling. However, additional information on the secondary and tertiary sources was obtained. Connectivity remained a significant factor in interpreting the results of the fractionated analysis. Specific sediment yields were estimated for each catchment source per particle size fraction group. These sediment yields provided a deeper understanding of sediment transport through a catchment and which particle size groups are most important in catchment erosion. An original contribution to research was made by estimating source contribution estimates for the four reservoirs, quantifying sediment yields for each catchment lithology and then for each catchment lithology by particle size. Mineral magnetic tracing of the catchments was applied for the first time in this region of South Africa. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
Biodiversity conservation of South Africa’s Wild Coast through the years: Exploring the tensions between western-style and local traditional conservation practices
- Authors: De Villiers, Deon Johan
- Date: 2021-10-29
- Subjects: Biodiversity conservation South Africa Eastern Cape , Political ecology South Africa Eastern Cape , Dwesa Nature Reserve (South Africa) , Mkambati Nature Reserve (South Africa) , Hluleka Nature Reserve (South Africa) , Environmental policy South Africa , Natural resources Co-management South Africa Eastern Cape , Land use Environmental aspects South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190646 , vital:45013 , 10.21504/10962/190646
- Description: The Transkei Wild Coast is a unique and diverse biophysical environment stretching some 280 kilometres between the Great Kei and Mtamvuna Rivers along South Africa’s eastern coastline. Its extensive indigenous forests were recognised for their biological and economic importance by the colonial government and granted protection from the late 1800s, with forced removal of indigenous people who resided within them. The state restricted and controlled the utilisation of the forest resources, particularly by Black people, through promulgation and enforcement of legislation. Similar conservation methods were employed for protection of the Wild Coast’s soils, grasslands and marine resources, usually without any consultation with local Black leadership or communities who relied upon these resources. Previous studies have focussed on the impacts of Western-style conservation legislation and the promulgation of protected areas on local people. These have suggested that local communities have been denied access to natural resources through a fences and fines approach, often accompanied by heavy-handed, strict law enforcement measures. Very little research has been conducted to document the actual reasons for and the history of conservation efforts along the Wild Coast. The aim of this study was to explore the history of natural resource management and conservation along the Wild Coast from a Western and African perspective, and to examine the conflicts that have arisen as a result thereof. The importance of utilisation of natural resources to sustain livelihoods and the conservation methods applied to protect these resources were examined, mainly by means of a literature review and face-to-face interviews with local traditional leaders and environmental managers. The successes, challenges and conflicts that resulted from conservation efforts were examined through detailed analysis of the conservation history of three case study areas: Dwesa-Cwebe, Hluleka and Mkambati nature reserves. The study concludes that traditional leaders, foresters and conservation managers have largely been ignored during previous research on management and conservation of the Wild Coast; however, they were very eager to express their views on this subject. The interviews revealed that traditional leaders and conservationists from each case study area want to protect the Wild Coast and its natural resources, albeit for different reasons. Conservationists recognise the importance of the region’s biodiversity and the need for protected areas, particularly where there is rich endemism such as at Mkambati and Dwesa-Cwebe. Traditional leaders recognise the potential for jobs for their people where protected areas preserve the aesthetic beauty of the coast and attract tourists. For them, employment opportunities are a priority, as is access to utilisation of natural resources to sustain livelihoods. The traditional customs and culture of the people living along the Wild Coast are also seen as being of critical importance. This has not been adequately considered by past conservation planners and managers, but traditional leaders express value in conserving the amaXhosa and amaMpondo way of life. Nowhere is this more evident than in relation to grazing land for cattle. Another significant finding is that the support shown by traditional leaders for conservation of the terrestrial environment is not necessarily mirrored when it comes to protection of marine resources. The Wild Coast has a rich variety of marine flora and fauna and a high percentage of endemic species. Local people have relied upon marine resources for sustenance, but conservationists acknowledge that access to these resources has historically been restricted without consultation with traditional leaders or local communities. It is concluded that these restrictions can be linked to many land claims on protected areas on the Wild Coast since 1994. While this study suggests that both traditional leaders and conservationists want to protect the Wild Coast and its natural resources, there is still mistrust based on a history of unjust forced removals from forests, restrictions on the use of natural resources through the manifestation of colonial and apartheid power, and broken promises relating to benefit sharing from proceeds of wildlife and tourism ventures, as well as those benefits linked to land claim settlement agreements in the post-apartheid era. The study concludes that, despite past conflicts relating to conservation management, the Wild Coast’s protected areas have widespread support amongst traditional leaders. There is agreement that co-management is the preferred option but the state has to assist in curbing lawlessness that threatens over-exploitation of natural resources. It is largely acknowledged by conservationists that local people should be permitted to sustainably use certain natural resources and that there have to be increased economic benefits from tourism. Although protected area managers cannot be expected to carry the responsibility of failed tourism models and economic ventures on nature reserves, this study found that they are often the only government officials available on the ground for traditional leaders and local communities to consult with. For co-management to be successful on the protected areas, regular communication about all matters pertaining to management is considered important. While it is accepted that traditional leaders no longer have the administrative powers that they historically possessed, the study found that they are still widely respected along the Wild Coast. It is therefore concluded that regular consultation between environmental managers and traditional leaders is essential for the future conservation of the Wild Coast. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: De Villiers, Deon Johan
- Date: 2021-10-29
- Subjects: Biodiversity conservation South Africa Eastern Cape , Political ecology South Africa Eastern Cape , Dwesa Nature Reserve (South Africa) , Mkambati Nature Reserve (South Africa) , Hluleka Nature Reserve (South Africa) , Environmental policy South Africa , Natural resources Co-management South Africa Eastern Cape , Land use Environmental aspects South Africa Eastern Cape
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/190646 , vital:45013 , 10.21504/10962/190646
- Description: The Transkei Wild Coast is a unique and diverse biophysical environment stretching some 280 kilometres between the Great Kei and Mtamvuna Rivers along South Africa’s eastern coastline. Its extensive indigenous forests were recognised for their biological and economic importance by the colonial government and granted protection from the late 1800s, with forced removal of indigenous people who resided within them. The state restricted and controlled the utilisation of the forest resources, particularly by Black people, through promulgation and enforcement of legislation. Similar conservation methods were employed for protection of the Wild Coast’s soils, grasslands and marine resources, usually without any consultation with local Black leadership or communities who relied upon these resources. Previous studies have focussed on the impacts of Western-style conservation legislation and the promulgation of protected areas on local people. These have suggested that local communities have been denied access to natural resources through a fences and fines approach, often accompanied by heavy-handed, strict law enforcement measures. Very little research has been conducted to document the actual reasons for and the history of conservation efforts along the Wild Coast. The aim of this study was to explore the history of natural resource management and conservation along the Wild Coast from a Western and African perspective, and to examine the conflicts that have arisen as a result thereof. The importance of utilisation of natural resources to sustain livelihoods and the conservation methods applied to protect these resources were examined, mainly by means of a literature review and face-to-face interviews with local traditional leaders and environmental managers. The successes, challenges and conflicts that resulted from conservation efforts were examined through detailed analysis of the conservation history of three case study areas: Dwesa-Cwebe, Hluleka and Mkambati nature reserves. The study concludes that traditional leaders, foresters and conservation managers have largely been ignored during previous research on management and conservation of the Wild Coast; however, they were very eager to express their views on this subject. The interviews revealed that traditional leaders and conservationists from each case study area want to protect the Wild Coast and its natural resources, albeit for different reasons. Conservationists recognise the importance of the region’s biodiversity and the need for protected areas, particularly where there is rich endemism such as at Mkambati and Dwesa-Cwebe. Traditional leaders recognise the potential for jobs for their people where protected areas preserve the aesthetic beauty of the coast and attract tourists. For them, employment opportunities are a priority, as is access to utilisation of natural resources to sustain livelihoods. The traditional customs and culture of the people living along the Wild Coast are also seen as being of critical importance. This has not been adequately considered by past conservation planners and managers, but traditional leaders express value in conserving the amaXhosa and amaMpondo way of life. Nowhere is this more evident than in relation to grazing land for cattle. Another significant finding is that the support shown by traditional leaders for conservation of the terrestrial environment is not necessarily mirrored when it comes to protection of marine resources. The Wild Coast has a rich variety of marine flora and fauna and a high percentage of endemic species. Local people have relied upon marine resources for sustenance, but conservationists acknowledge that access to these resources has historically been restricted without consultation with traditional leaders or local communities. It is concluded that these restrictions can be linked to many land claims on protected areas on the Wild Coast since 1994. While this study suggests that both traditional leaders and conservationists want to protect the Wild Coast and its natural resources, there is still mistrust based on a history of unjust forced removals from forests, restrictions on the use of natural resources through the manifestation of colonial and apartheid power, and broken promises relating to benefit sharing from proceeds of wildlife and tourism ventures, as well as those benefits linked to land claim settlement agreements in the post-apartheid era. The study concludes that, despite past conflicts relating to conservation management, the Wild Coast’s protected areas have widespread support amongst traditional leaders. There is agreement that co-management is the preferred option but the state has to assist in curbing lawlessness that threatens over-exploitation of natural resources. It is largely acknowledged by conservationists that local people should be permitted to sustainably use certain natural resources and that there have to be increased economic benefits from tourism. Although protected area managers cannot be expected to carry the responsibility of failed tourism models and economic ventures on nature reserves, this study found that they are often the only government officials available on the ground for traditional leaders and local communities to consult with. For co-management to be successful on the protected areas, regular communication about all matters pertaining to management is considered important. While it is accepted that traditional leaders no longer have the administrative powers that they historically possessed, the study found that they are still widely respected along the Wild Coast. It is therefore concluded that regular consultation between environmental managers and traditional leaders is essential for the future conservation of the Wild Coast. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
Spatial analysis of the impact of human activities on the marine environment in Algoa Bay, South Africa
- Authors: Maphoto, Tidimalo Mary Anne
- Date: 2021-10-29
- Subjects: Marine resources conservation Algoa Bay South Africa , Spatial analysis (Statistics) , Human ecology , Nature Effect of human beings on , Marine ecology Algoa Bay South Africa , Integrated coastal zone management Algoa Bay South Africa , Marine spatial planning Algoa Bay South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192086 , vital:45194
- Description: Background: Humans have a long history of using the marine environment in multiple ways and continued use has led to a decline in the ecosystem services provided by marine systems in many places. In addition, human activities have steadily increased with time and advances in technology, further increasing impacts on marine systems. To understand and manage these impacts, we need to assess the spatial distribution and intensity of human activities in the marine environment, and quantify, where possible, their cumulative impacts on marine ecosystems. The spatial consideration of human activities and their associated impacts is important for conservation planning, Integrated Ocean Management and Marine Spatial Planning (MSP) initiatives. The main deliverable of this research study was to develop a cumulative impacts layer of human activities in Algoa Bay, South Africa, to support the Algoa Bay Marine Spatial Planning Project. Objective and Relevance: This research analyses the spatial impacts of human activities on the Algoa Bay marine environment (excluding the seashore). Algoa Bay is located on the south coast of South Africa in the Eastern Cape. The research explores stakeholders' perceptions of their knowledge of the human activities that take place in the bay. This research is informed by an expert-based geographical information systems (GIS) approach and cumulative impact assessment in order to map the spatial impacts of the activities as part of marine spatial planning. "Experts" were defined as stakeholders that contributed valuable knowledge of the human activities and their impacts; this definition of expert included "professional" and "non-professional" contributors to knowledge. The spatial aspect of the research is a significant contribution to the field as it will help inform decision-making in the Algoa Bay Marine Spatial Planning Project. Design and Methods: A mixed-method approach was used to generate data. A snowball sampling approach was used to identify research participants from key informants. Primary data were collected through questionnaire surveys, interviews and a focus group. Secondary data sources consisted of GIS data and reports from scientific organizations. Findings and Conclusion: The research findings indicate that the top three pressures that cause the greatest impact on the Algoa Bay marine environment are fishing, pollution and shipping. The cumulative impact of these activities was highest near harbours in Algoa Bay. The marine ecosystems that were most impacted by pressures were the Agulhas Island and the Agulhas Mixed Shore. The Warm Temperate marine ecosystems had fairly low cumulative impacts. The research findings indicate that there is a complex mix of human activities that impact the marine environment. This research supports the findings of other researchers that reveal that the highest cumulative impact is in areas closer to the coast and harbours owing to high population densities. Value of Study: This study builds onto the existing data by expanding the knowledge base and including more stakeholders to integrate as many human activities as possible and bring a holistic picture of the ocean's uses to inform MSP in Algoa Bay. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: Maphoto, Tidimalo Mary Anne
- Date: 2021-10-29
- Subjects: Marine resources conservation Algoa Bay South Africa , Spatial analysis (Statistics) , Human ecology , Nature Effect of human beings on , Marine ecology Algoa Bay South Africa , Integrated coastal zone management Algoa Bay South Africa , Marine spatial planning Algoa Bay South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192086 , vital:45194
- Description: Background: Humans have a long history of using the marine environment in multiple ways and continued use has led to a decline in the ecosystem services provided by marine systems in many places. In addition, human activities have steadily increased with time and advances in technology, further increasing impacts on marine systems. To understand and manage these impacts, we need to assess the spatial distribution and intensity of human activities in the marine environment, and quantify, where possible, their cumulative impacts on marine ecosystems. The spatial consideration of human activities and their associated impacts is important for conservation planning, Integrated Ocean Management and Marine Spatial Planning (MSP) initiatives. The main deliverable of this research study was to develop a cumulative impacts layer of human activities in Algoa Bay, South Africa, to support the Algoa Bay Marine Spatial Planning Project. Objective and Relevance: This research analyses the spatial impacts of human activities on the Algoa Bay marine environment (excluding the seashore). Algoa Bay is located on the south coast of South Africa in the Eastern Cape. The research explores stakeholders' perceptions of their knowledge of the human activities that take place in the bay. This research is informed by an expert-based geographical information systems (GIS) approach and cumulative impact assessment in order to map the spatial impacts of the activities as part of marine spatial planning. "Experts" were defined as stakeholders that contributed valuable knowledge of the human activities and their impacts; this definition of expert included "professional" and "non-professional" contributors to knowledge. The spatial aspect of the research is a significant contribution to the field as it will help inform decision-making in the Algoa Bay Marine Spatial Planning Project. Design and Methods: A mixed-method approach was used to generate data. A snowball sampling approach was used to identify research participants from key informants. Primary data were collected through questionnaire surveys, interviews and a focus group. Secondary data sources consisted of GIS data and reports from scientific organizations. Findings and Conclusion: The research findings indicate that the top three pressures that cause the greatest impact on the Algoa Bay marine environment are fishing, pollution and shipping. The cumulative impact of these activities was highest near harbours in Algoa Bay. The marine ecosystems that were most impacted by pressures were the Agulhas Island and the Agulhas Mixed Shore. The Warm Temperate marine ecosystems had fairly low cumulative impacts. The research findings indicate that there is a complex mix of human activities that impact the marine environment. This research supports the findings of other researchers that reveal that the highest cumulative impact is in areas closer to the coast and harbours owing to high population densities. Value of Study: This study builds onto the existing data by expanding the knowledge base and including more stakeholders to integrate as many human activities as possible and bring a holistic picture of the ocean's uses to inform MSP in Algoa Bay. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
Understanding human‐wildlife conflict: a geographic study of the Pringle Bay chacma baboon troop
- Authors: Parsons, Wendy Jennifer
- Date: 2021-10-29
- Subjects: Chacma baboon South Africa Pringle Bay , Human-animal relationships South Africa Pringle Bay , Radio collars , Geographic information systems , Chacma baboon South Africa Pringle Bay Geographical distribution , Chacma baboon Behavior South Africa Pringle Bay , Chacma baboon Effect of human beings on South Africa Pringle Bay , Geospatial data , User-generated content
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/294828 , vital:57259
- Description: A better appreciation of the physical geography and environmental factors that play a role in the movement of the Chacma baboon troop in and around Pringle Bay (Overberg Municipality) and part of the Kogelberg Biosphere could lead to a better understanding of their movement. In turn, this insight may contribute to reducing the human‐wildlife conflict that has arisen in the town. Humanwildlife conflict escalated after the rapid urban development that followed the introduction of electricity in 1993. The baboon‐human conflict in Pringle Bay is, in part, due to habitat loss caused by urban development and the easy availability of food in the urban area. The wild animal’s natural behaviour (seeking food and fresh water) and the human way of living (food and waste management) has led to baboon habituation and increased raiding in the village. The objective of this geographic study was to understand the baboon troops spatial and temporal movements. Two methods are being used to track the baboon troop. The first method entails collection of data from GPS tracking collars which record the location of the baboons at 30 minute intervals. This is considered a reliable, but invasive and expensive method where the alpha male and female baboon had to be captured and fitted with tracking collars. The second method entails using volunteered geographic data, in this case, information from a WhatsApp baboon alert group. While this provided data at no real cost, the mining of the information was challenging and building a geodatabase was time consuming. However, this citizen science approach added valuable data and was able to identify human‐wildlife conflict sites in the urban area. The baboon location data was mapped using GIS. Primary and secondary spatial data was sourced and added to the geodatabase created in ArcMap 10.7. Various ArcMap tools were used in analysing the environmental factors (climate, vegetation, water sources and topography) together with the location data. Analysis of this data allowed the range of the baboons to be mapped, showing the maximum extent of the territory the baboons move in. The was refined by mapping their home range (defined as the area in which they spend 95% of the time) and their core area (in which they spend 50% of the time). High activity areas ‐ or hotspots ‐ were identified, as were the baboon sleep sites. The data allowed for habitat use and seasonal patterns of movement to be explored. A key finding of the research was that the baboons were observed outside of the urban area for 82% of the time. The baboons spent the majority of their time in mountain fynbos vegetation. Hotspot areas showing significant baboon activity were identified within the town and close correlation with their sleep sites and wetland areas was evident. No definitive seasonal or weather patterns were found that influence the baboon distribution. Baboon management is complex and difficult. The sustainability of the baboon troop is important for the biodiversity of the Kogelberg Biosphere Reserve. While the baboons should not be encouraged to enter the urban area, the residents should play a role in reducing the availability of food and baboonproofing their properties. The Overstrand Municipality also needs to address waste management and waste collection in the town. Understanding the biogeography of the baboons and implementing the above‐mentioned mitigating management measures would encourage human‐wildlife coexistence and inform future baboon management plans. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: Parsons, Wendy Jennifer
- Date: 2021-10-29
- Subjects: Chacma baboon South Africa Pringle Bay , Human-animal relationships South Africa Pringle Bay , Radio collars , Geographic information systems , Chacma baboon South Africa Pringle Bay Geographical distribution , Chacma baboon Behavior South Africa Pringle Bay , Chacma baboon Effect of human beings on South Africa Pringle Bay , Geospatial data , User-generated content
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/294828 , vital:57259
- Description: A better appreciation of the physical geography and environmental factors that play a role in the movement of the Chacma baboon troop in and around Pringle Bay (Overberg Municipality) and part of the Kogelberg Biosphere could lead to a better understanding of their movement. In turn, this insight may contribute to reducing the human‐wildlife conflict that has arisen in the town. Humanwildlife conflict escalated after the rapid urban development that followed the introduction of electricity in 1993. The baboon‐human conflict in Pringle Bay is, in part, due to habitat loss caused by urban development and the easy availability of food in the urban area. The wild animal’s natural behaviour (seeking food and fresh water) and the human way of living (food and waste management) has led to baboon habituation and increased raiding in the village. The objective of this geographic study was to understand the baboon troops spatial and temporal movements. Two methods are being used to track the baboon troop. The first method entails collection of data from GPS tracking collars which record the location of the baboons at 30 minute intervals. This is considered a reliable, but invasive and expensive method where the alpha male and female baboon had to be captured and fitted with tracking collars. The second method entails using volunteered geographic data, in this case, information from a WhatsApp baboon alert group. While this provided data at no real cost, the mining of the information was challenging and building a geodatabase was time consuming. However, this citizen science approach added valuable data and was able to identify human‐wildlife conflict sites in the urban area. The baboon location data was mapped using GIS. Primary and secondary spatial data was sourced and added to the geodatabase created in ArcMap 10.7. Various ArcMap tools were used in analysing the environmental factors (climate, vegetation, water sources and topography) together with the location data. Analysis of this data allowed the range of the baboons to be mapped, showing the maximum extent of the territory the baboons move in. The was refined by mapping their home range (defined as the area in which they spend 95% of the time) and their core area (in which they spend 50% of the time). High activity areas ‐ or hotspots ‐ were identified, as were the baboon sleep sites. The data allowed for habitat use and seasonal patterns of movement to be explored. A key finding of the research was that the baboons were observed outside of the urban area for 82% of the time. The baboons spent the majority of their time in mountain fynbos vegetation. Hotspot areas showing significant baboon activity were identified within the town and close correlation with their sleep sites and wetland areas was evident. No definitive seasonal or weather patterns were found that influence the baboon distribution. Baboon management is complex and difficult. The sustainability of the baboon troop is important for the biodiversity of the Kogelberg Biosphere Reserve. While the baboons should not be encouraged to enter the urban area, the residents should play a role in reducing the availability of food and baboonproofing their properties. The Overstrand Municipality also needs to address waste management and waste collection in the town. Understanding the biogeography of the baboons and implementing the above‐mentioned mitigating management measures would encourage human‐wildlife coexistence and inform future baboon management plans. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
Investigation of sediment buffering function of the Gatberg Floodplain Wetland in the upper Tsitsa River Catchment, South Africa
- Pakati, Sibuyisele Sweetness
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa
- Authors: Memela, Sinenhlanhla
- Date: 2021-04-28
- Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
- Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
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:
- 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:
The role of open government data in the repurposing of land administration in postapartheid South Africa : an exploration
- Authors: Manona, Siyabulela Sobantu
- Date: 2021-04
- Subjects: Transparency in government -- South Africa , Land reform -- South Africa , Qualitative research -- Methodology , Postcolonialism -- South Africa , Post-apartheid era -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994- , South Africa -- Politics and government -- 1994- , Open Government Data (OGD)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178397 , vital:42936 , 10.21504/10962/178397
- Description: Almost three decades after the official end of the apartheid, South Africa has been on a sturdy path that is characterised by deepening spatial economic inequalities. A plethora of policy instruments unleashed since 1994 had not only failed to stem the tide of poverty and inequality, but had deepened them. As part of this, South Africa’s most ambitious social engineering programme – land reform -- had disappointing outcomes. Premised on a view that these apartheid continuities were embedded in South Africa’s land administration system – which was incoherent and fragmented and requiring a systemic overhaul -- the study sought to explore the potential role of Open Government Data (OGD) in the repurposing of land administration system in the post-apartheid South Africa. To achieve this goal, the study was guided by the following objectives: to explore the ontology and the state of land governance and administration in the context of the post-apartheid South Africa; to undertake an evaluation or assessment of South Africa’s land data ecosystem; and to explore the potential role of OGD in the repurposing of land administration system in the postapartheid of South Africa. This study was steeped in qualitative research methods, underpinned by primary and secondary literature review. While the study was primarily pitched on a national scale – the combination of the systems and multiple scales approaches – yielded results which dislodges solutions that are required outside of the domain of a single state. This is one glaring example of land governance complexities that straddle beyond national scale – specifically in respect of new policy trajectories on trans-national boundaries and governance of water resources. Based on the holistic ontology of land, this study concludes that land administration and land governance overarching conceptual orientation -- concerned with land use decisions made by humans at various scales from a praxis and policy perspective –constitute two sides of the same coin, the former steeped towards practice and the latter steeped towards policy. Drawing from decolonial theories the study concludes that land does not only have multiple dimensions, but it also has multiple meanings, in a manner that calls for an ontological shift away from the western ontology, towards an inclusive and holistic conceptualisation. Historiography that is anchored in de-colonial thinking of South Africa’s land governance helps us understand how and why – colonial/apartheid norms acrimoniously found their way into the post-apartheid order -- the post-apartheid institutions of modernity rest on the same hierarchies of identities, classification and pathologisation. The study concludes that, while the colonial/apartheid administration may be gone, it’s underlying power matrices continue -- i.e. capitalism/European/patriachal/white – in a manner which explains the continuities of South Africa’s spatial inequalities and the associated economic inequalities. The organising principle for land relations (including opportunities) continues to be underpinned by gender, race and class, in ways that expose the mythical dimensions of the 'post-apartheid' underbelly. While identifying the need for homogenisation and rationalistion of colonial, apartheid and post-apartheid institutions (on a national scale) that is insufficient for the transformation of the colonial situation of what is in essence a part of the global system, the study advocates for the ‘repurposing of land governance and administration’ – underpinned by de-colonial thinking. Repurposing is seen as political imaginary that would entail uncoupling thought processes and praxis from the colonial matrices of power. The study goes on to conclude that there is a definite role for Open Government Data in repurposing of land administration in the post-apartheid South Africa – as a necessary, though in and of it’s own it is an insufficient condition to achieve that ideal -- but presents an opportunity to enhance transdisciplinarity approaches and efficiencies in internal government functioning and evidence-based decision making and policy formulation processes. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
- Authors: Manona, Siyabulela Sobantu
- Date: 2021-04
- Subjects: Transparency in government -- South Africa , Land reform -- South Africa , Qualitative research -- Methodology , Postcolonialism -- South Africa , Post-apartheid era -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994- , South Africa -- Politics and government -- 1994- , Open Government Data (OGD)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178397 , vital:42936 , 10.21504/10962/178397
- Description: Almost three decades after the official end of the apartheid, South Africa has been on a sturdy path that is characterised by deepening spatial economic inequalities. A plethora of policy instruments unleashed since 1994 had not only failed to stem the tide of poverty and inequality, but had deepened them. As part of this, South Africa’s most ambitious social engineering programme – land reform -- had disappointing outcomes. Premised on a view that these apartheid continuities were embedded in South Africa’s land administration system – which was incoherent and fragmented and requiring a systemic overhaul -- the study sought to explore the potential role of Open Government Data (OGD) in the repurposing of land administration system in the post-apartheid South Africa. To achieve this goal, the study was guided by the following objectives: to explore the ontology and the state of land governance and administration in the context of the post-apartheid South Africa; to undertake an evaluation or assessment of South Africa’s land data ecosystem; and to explore the potential role of OGD in the repurposing of land administration system in the postapartheid of South Africa. This study was steeped in qualitative research methods, underpinned by primary and secondary literature review. While the study was primarily pitched on a national scale – the combination of the systems and multiple scales approaches – yielded results which dislodges solutions that are required outside of the domain of a single state. This is one glaring example of land governance complexities that straddle beyond national scale – specifically in respect of new policy trajectories on trans-national boundaries and governance of water resources. Based on the holistic ontology of land, this study concludes that land administration and land governance overarching conceptual orientation -- concerned with land use decisions made by humans at various scales from a praxis and policy perspective –constitute two sides of the same coin, the former steeped towards practice and the latter steeped towards policy. Drawing from decolonial theories the study concludes that land does not only have multiple dimensions, but it also has multiple meanings, in a manner that calls for an ontological shift away from the western ontology, towards an inclusive and holistic conceptualisation. Historiography that is anchored in de-colonial thinking of South Africa’s land governance helps us understand how and why – colonial/apartheid norms acrimoniously found their way into the post-apartheid order -- the post-apartheid institutions of modernity rest on the same hierarchies of identities, classification and pathologisation. The study concludes that, while the colonial/apartheid administration may be gone, it’s underlying power matrices continue -- i.e. capitalism/European/patriachal/white – in a manner which explains the continuities of South Africa’s spatial inequalities and the associated economic inequalities. The organising principle for land relations (including opportunities) continues to be underpinned by gender, race and class, in ways that expose the mythical dimensions of the 'post-apartheid' underbelly. While identifying the need for homogenisation and rationalistion of colonial, apartheid and post-apartheid institutions (on a national scale) that is insufficient for the transformation of the colonial situation of what is in essence a part of the global system, the study advocates for the ‘repurposing of land governance and administration’ – underpinned by de-colonial thinking. Repurposing is seen as political imaginary that would entail uncoupling thought processes and praxis from the colonial matrices of power. The study goes on to conclude that there is a definite role for Open Government Data in repurposing of land administration in the post-apartheid South Africa – as a necessary, though in and of it’s own it is an insufficient condition to achieve that ideal -- but presents an opportunity to enhance transdisciplinarity approaches and efficiencies in internal government functioning and evidence-based decision making and policy formulation processes. , Thesis (PhD) -- Faculty of Science, Geography, 2021
- Full Text:
An assessment of the effectiveness of the Crossways Farm Village constructed wetland in the treatment of domestic wastewater
- Authors: Silbernagl, Ryan
- Date: 2020
- Subjects: Crossways Farm Village FWS wetland (South Africa)-- Management , Sewage -- Purification -- South Africa , Wetland management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145011 , vital:38400
- Description: A mass balance study was conducted comparing inflowing and outflowing solute loads in order to calculate the treatment efficiency of a free water surface (FWS) constructed wetland used to treat domestic wastewater following primary treatment in an anaerobic reactor and oxidation in a rotating biological contractor. Water samples were taken at six locations down the length of the treatment system and analysed for nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N), ammonia nitrogen (NH4-N) and phosphorus as phosphate (PO4-P). Flow was determined using two V notch weirs combined with pressure transducers based on an empirically derived stage-discharge relationship. The concentration of each solute (g.m-3) multiplied by flow (m3.day-1) provides a measurement of the mass of each solute entering and leaving the treatment wetland such that the difference (inflow – outflow) indicates the nett storage in, or loss from, the wetland. In order to determine the water balance, apart from measuring surface inflows and outflows, rainfall was measured using an onsite rain gauge. Evapotranspirational losses were determined using the Penman-Monteith equation based on weather data collected at an onsite weather station. Other than water that entered the wetland via the primary water treatment works, surface inflows could be ignored as the wetland was sealed with a plastic liner, which also prevented groundwater inflow and outflow. Wetland outputs via surface outflow and evapotranspiration were then subtracted from wetland inputs to determine the water balance over the study period. Approximately 10.5% of water inputs into the hydrological mass balance calculation was not accounted for, which is considered to be accounted for by inaccuracy associated with the estimation of evapotranspiration and possibly by differences in water levels in the wetland at the start and end of the experiment. Total input, output and storage of NO3-N, NO2-N, NH4-N and PO4-P was calculated from April 2016 to September 2016 to give the treatment efficiency of the FWS wetland system. Results showed a 91.5% reduction in NO3-N, 76.6% reduction in NH4-N, and 88.8% reduction in PO4P between the inflow and outflow. Wetland sediment and vegetation (Typha capensis) samples were also analysed for nitrogen and phosphorus content to give an estimate of nutrient stocks/storage accumulated in plant tissues and sediments over the lifespan of the wetland. Standing stock calculations showed that a total of 450.1kg of nitrogen is stored in the wetlands, of which 69.3kg is stored in wetland sediments. Wetland phosphorus retention was found to be significantly lower with a total of 57.1kg of phosphorus, of which 77.4% was stored in sediments, indicating that wetland sediments comprise the largest store and therefore removal pathway of nutrients in the Crossways Farm Village FWS wetland.
- Full Text:
- Authors: Silbernagl, Ryan
- Date: 2020
- Subjects: Crossways Farm Village FWS wetland (South Africa)-- Management , Sewage -- Purification -- South Africa , Wetland management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145011 , vital:38400
- Description: A mass balance study was conducted comparing inflowing and outflowing solute loads in order to calculate the treatment efficiency of a free water surface (FWS) constructed wetland used to treat domestic wastewater following primary treatment in an anaerobic reactor and oxidation in a rotating biological contractor. Water samples were taken at six locations down the length of the treatment system and analysed for nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N), ammonia nitrogen (NH4-N) and phosphorus as phosphate (PO4-P). Flow was determined using two V notch weirs combined with pressure transducers based on an empirically derived stage-discharge relationship. The concentration of each solute (g.m-3) multiplied by flow (m3.day-1) provides a measurement of the mass of each solute entering and leaving the treatment wetland such that the difference (inflow – outflow) indicates the nett storage in, or loss from, the wetland. In order to determine the water balance, apart from measuring surface inflows and outflows, rainfall was measured using an onsite rain gauge. Evapotranspirational losses were determined using the Penman-Monteith equation based on weather data collected at an onsite weather station. Other than water that entered the wetland via the primary water treatment works, surface inflows could be ignored as the wetland was sealed with a plastic liner, which also prevented groundwater inflow and outflow. Wetland outputs via surface outflow and evapotranspiration were then subtracted from wetland inputs to determine the water balance over the study period. Approximately 10.5% of water inputs into the hydrological mass balance calculation was not accounted for, which is considered to be accounted for by inaccuracy associated with the estimation of evapotranspiration and possibly by differences in water levels in the wetland at the start and end of the experiment. Total input, output and storage of NO3-N, NO2-N, NH4-N and PO4-P was calculated from April 2016 to September 2016 to give the treatment efficiency of the FWS wetland system. Results showed a 91.5% reduction in NO3-N, 76.6% reduction in NH4-N, and 88.8% reduction in PO4P between the inflow and outflow. Wetland sediment and vegetation (Typha capensis) samples were also analysed for nitrogen and phosphorus content to give an estimate of nutrient stocks/storage accumulated in plant tissues and sediments over the lifespan of the wetland. Standing stock calculations showed that a total of 450.1kg of nitrogen is stored in the wetlands, of which 69.3kg is stored in wetland sediments. Wetland phosphorus retention was found to be significantly lower with a total of 57.1kg of phosphorus, of which 77.4% was stored in sediments, indicating that wetland sediments comprise the largest store and therefore removal pathway of nutrients in the Crossways Farm Village FWS wetland.
- Full Text: