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:
- Date Issued: 2022-04-06
- 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:
- Date Issued: 2022-04-06
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:
- Date Issued: 2021-10-29
- 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:
- Date Issued: 2021-10-29
The zoogeography of the cetaceans in Algoa Bay
- Authors: Melly, Brigitte Leigh
- Date: 2011
- Subjects: Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4858 , http://hdl.handle.net/10962/d1005534 , Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Description: The most recent study on cetaceans in Algoa Bay, South Africa, was conducted over 14 years ago. Consequently, knowledge of the cetacean species visiting this bay is currently based on incidental observations and stranding data. A number of developments in recent years: a deepwater port, proposed oil refinery, increased boating and fishing (commercial and recreational), a proposed Marine Protected Area, and the release of a whale-watching permit, all of which may impact these animals in some way, highlight the need for a baseline study on cetaceans. Therefore, the aim of this study was to determine the spatial and temporal distribution, and habitat preference of cetaceans in Algoa Bay. Boat-based surveys were conducted monthly between March 2009 and July 2010. At each sighting the GPS location, species, group size and composition, and behaviour were recorded. Using GIS, the sighting data was related to data layers of geographical variables such as sea surface temperature, depth and sea-floor substrate. Approximately 365 hours of search effort were completed over 57 surveys, with a total of 346 sightings. Species observed were: southern right whales (Eubalaena australis), humpback whales (Megaptera novaeangliae), Bryde’s whales (Balaenoptera brydei), Indian Ocean bottlenose dolphins (Tursiops aduncus), Indo-Pacific humpback dolphins (Sousa chinensis), and longbeaked common dolphins (Delphinus capensis). Southern right whales were observed during austral winter, utilising the shallow, protected areas of the bay as a mating and nursery ground. Humpback whales were also recorded extensively during winter, in more offshore waters, with a significant number of mother-calf pairs sighted. Bryde’s whales were recorded in offshore waters during summer and autumn, where they were primarily observed travelling and foraging. Bottlenose dolphins were the most prolific species sighted. They were recorded year-round throughout the inshore waters of the bay, with large group sizes (up to 500 animals), and displayed a wide variety of behaviours. Humpback dolphins were observed in extremely shallow and inshore waters (mean bottom depth of 6.6 m) along the south-west corner of the bay, in small groups of approximately three individuals. Common dolphins were the least observed species, and were mainly observed foraging in large groups of up to 800 individuals. The results of this study indicate how cetaceans utilise the bay in significantly different ways. Geographical and anthropogenic factors have influenced the spatial and temporal distribution of these animals and have resulted in habitat preferences, as well as potential key habitats, in the bay. Thus, this study has provided baseline information for future research and for better informed conservation and management strategies in Algoa Bay.
- Full Text:
- Date Issued: 2011
- Authors: Melly, Brigitte Leigh
- Date: 2011
- Subjects: Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4858 , http://hdl.handle.net/10962/d1005534 , Cetacea -- South Africa -- Algoa Bay , Cetacea -- Behavior -- South Africa -- Algoa Bay , Cetacea -- South Africa -- Algoa Bay -- Geographical distribution , Cetacea -- Counting -- South Africa -- Algoa Bay
- Description: The most recent study on cetaceans in Algoa Bay, South Africa, was conducted over 14 years ago. Consequently, knowledge of the cetacean species visiting this bay is currently based on incidental observations and stranding data. A number of developments in recent years: a deepwater port, proposed oil refinery, increased boating and fishing (commercial and recreational), a proposed Marine Protected Area, and the release of a whale-watching permit, all of which may impact these animals in some way, highlight the need for a baseline study on cetaceans. Therefore, the aim of this study was to determine the spatial and temporal distribution, and habitat preference of cetaceans in Algoa Bay. Boat-based surveys were conducted monthly between March 2009 and July 2010. At each sighting the GPS location, species, group size and composition, and behaviour were recorded. Using GIS, the sighting data was related to data layers of geographical variables such as sea surface temperature, depth and sea-floor substrate. Approximately 365 hours of search effort were completed over 57 surveys, with a total of 346 sightings. Species observed were: southern right whales (Eubalaena australis), humpback whales (Megaptera novaeangliae), Bryde’s whales (Balaenoptera brydei), Indian Ocean bottlenose dolphins (Tursiops aduncus), Indo-Pacific humpback dolphins (Sousa chinensis), and longbeaked common dolphins (Delphinus capensis). Southern right whales were observed during austral winter, utilising the shallow, protected areas of the bay as a mating and nursery ground. Humpback whales were also recorded extensively during winter, in more offshore waters, with a significant number of mother-calf pairs sighted. Bryde’s whales were recorded in offshore waters during summer and autumn, where they were primarily observed travelling and foraging. Bottlenose dolphins were the most prolific species sighted. They were recorded year-round throughout the inshore waters of the bay, with large group sizes (up to 500 animals), and displayed a wide variety of behaviours. Humpback dolphins were observed in extremely shallow and inshore waters (mean bottom depth of 6.6 m) along the south-west corner of the bay, in small groups of approximately three individuals. Common dolphins were the least observed species, and were mainly observed foraging in large groups of up to 800 individuals. The results of this study indicate how cetaceans utilise the bay in significantly different ways. Geographical and anthropogenic factors have influenced the spatial and temporal distribution of these animals and have resulted in habitat preferences, as well as potential key habitats, in the bay. Thus, this study has provided baseline information for future research and for better informed conservation and management strategies in Algoa Bay.
- Full Text:
- Date Issued: 2011
The use of remote sensing and Geographic Information System (GIS) techniques, to interpret savanna ecosystem patterns in the Sabi Sand Game Reserve, Mpumalanga province
- Fortescue, Alexander Kenneth John
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
The use of Landsat ETM imagery as a suitable data capture source for alien acacia species for the WFW programme
- Authors: Cobbing, Benedict Louis
- Date: 2007
- Subjects: Geographic information systems , Global Positioning System , Landsat satellites , Agriculture -- Remote sensing , Geography -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4856 , http://hdl.handle.net/10962/d1005532 , Geographic information systems , Global Positioning System , Landsat satellites , Agriculture -- Remote sensing , Geography -- Remote sensing
- Description: Geographic Information System technology today allows for the rapid analysis of vast amounts of spatial and non-spatial data. The power of a GIS can only be effected with the rapid collection of accurate input data. This is particularly true in the case of the South African National Working for Water (WFW) Programme where large volumes of spatial data on alien vegetation infestations are captured throughout the country. Alien vegetation clearing contracts cannot be generated, for WFW, without this data, so that the accurate capture of such data is crucial to the success of the programme. Mapping Invasive Alien Plant (IAP) data within WFW is a perennial problem (Coetzee, pers com, 2002), because not enough mapping is being done to meet the annual requirements of the programme in the various provinces. This is re-iterated by Richardson, 2004, who states that there is a shortage of accurate data on IAP abundance in South Africa. Therefore there is a need to investigate alternate methods of data capture; such as remote sensing, whilst working within the existing WFW data capture standards. The aim of this research was to investigate the use of Landsat ETM imagery as a data capture source for mapping alien vegetation for the WFW Programme in terms of their approved mapping methods, for both automated and manual classification techniques. The automated and manual classification results were compared to control data captured by differential Global Positioning Systems (DGPS). The research tested the various methods of data capture using Landsat ETM images over a range of study sites of varying complexity: a simple grassland area, a medium complexity grassy fynbos site and a complicated indigenous forest site. An important component of the research was to develop a mapping (classification) Ranking System based upon variables identified by WFW as fundamental in data capture decision making: spatial and positional accuracy, time constraints and cost constraints for three typical alien invaded areas. The mapping Ranking System compared the results of the various mapping methods for each factor for the study sites against each other. This provided an indication of which mapping method is the most efficient or suitable for a particular area.
- Full Text:
- Date Issued: 2007
- Authors: Cobbing, Benedict Louis
- Date: 2007
- Subjects: Geographic information systems , Global Positioning System , Landsat satellites , Agriculture -- Remote sensing , Geography -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4856 , http://hdl.handle.net/10962/d1005532 , Geographic information systems , Global Positioning System , Landsat satellites , Agriculture -- Remote sensing , Geography -- Remote sensing
- Description: Geographic Information System technology today allows for the rapid analysis of vast amounts of spatial and non-spatial data. The power of a GIS can only be effected with the rapid collection of accurate input data. This is particularly true in the case of the South African National Working for Water (WFW) Programme where large volumes of spatial data on alien vegetation infestations are captured throughout the country. Alien vegetation clearing contracts cannot be generated, for WFW, without this data, so that the accurate capture of such data is crucial to the success of the programme. Mapping Invasive Alien Plant (IAP) data within WFW is a perennial problem (Coetzee, pers com, 2002), because not enough mapping is being done to meet the annual requirements of the programme in the various provinces. This is re-iterated by Richardson, 2004, who states that there is a shortage of accurate data on IAP abundance in South Africa. Therefore there is a need to investigate alternate methods of data capture; such as remote sensing, whilst working within the existing WFW data capture standards. The aim of this research was to investigate the use of Landsat ETM imagery as a data capture source for mapping alien vegetation for the WFW Programme in terms of their approved mapping methods, for both automated and manual classification techniques. The automated and manual classification results were compared to control data captured by differential Global Positioning Systems (DGPS). The research tested the various methods of data capture using Landsat ETM images over a range of study sites of varying complexity: a simple grassland area, a medium complexity grassy fynbos site and a complicated indigenous forest site. An important component of the research was to develop a mapping (classification) Ranking System based upon variables identified by WFW as fundamental in data capture decision making: spatial and positional accuracy, time constraints and cost constraints for three typical alien invaded areas. The mapping Ranking System compared the results of the various mapping methods for each factor for the study sites against each other. This provided an indication of which mapping method is the most efficient or suitable for a particular area.
- Full Text:
- Date Issued: 2007
The suspended sediment yield and provenance of the Inxu River Catchment, Eastern Cape
- Authors: Nyamela, Namso
- Date: 2019
- Subjects: Suspended sediments -- South Africa -- Inxu River , Sedimentation and deposition -- South Africa -- Inxu River , Watershed management -- South Africa -- Inxu River , Erosion -- South Africa -- Inxu River , Soil erosion -- South Africa -- Inxu River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72150 , vital:30010
- Description: The excessive deposition and accumulation of suspended sediment leads to the degradation of water resources such as dams and rivers. For the purpose of preserving and protecting these resources, suspended sediment needs to be managed, and its management should be catchment-wide and catchment-specific. This is certainly the case for the eroded Inxu River Catchment, which has been identified as a major contributor of sediment to the planned Lalini Dam on the Tsitsa River (a tributary of the Mzimvubu River). Knowledge of suspended sediment flux and catchment sources will aid the design of relevant strategies to manage suspended sediment production. Suspended sediment flux was determined from sediment samples that were collected using citizen-based monitoring techniques at calendar- and event-based sampling frequency, along with discharges estimated using stage-discharge relationships. Sediment source areas were identified by determining the suspended sediment contribution from major sub-catchments and observing similarities in the characteristics of the sub-catchments that produced the most sediment. The Inxu River Catchment produced 5.5 t/ha/yr between 01 May 2016 and 30 April 2017. When compared to modelled sediment yield (7 t/ha/yr) from Le Roux et al. (2015), modelled output was not far off from the measured results and both measured and modelled results identified similar sediment source areas. Q-SSC relationships observed at the Inxu River Outlet indicated that sediment was eroded from local areas and sub-catchment sediment contribution confirmed that most of the sediment was from the lower Inxu River Catchment. Within this area, the Ncolosi and Qwakele River Sub-catchments were major sediment source areas and were subject to widespread gully erosion. Gully erosion was prominent on gentle slopes, foot slopes and valley-bottoms that have concave slope curvature and lie on the Tarkastad Formation. This Formation is associated with some of the most dispersive soils in the area. Moreover, the catchment is vulnerable to erosion due to cultivation and subsequent land abandonment, continuous grazing and dense rural populations. Other studies in the Mzimvubu catchment identified similar catchment characteristics that contribute to excessive erosion. This study has successfully measured sediment yield and identified areas that should be targeted and prioritised for rehabilitation within the Inxu River Catchment. The findings could be applied to a wider catchment scale. The study has successfully demonstrated the use of citizen-based monitoring and desktop techniques and has also identified some pitfalls of this approach.
- Full Text:
- Date Issued: 2019
- Authors: Nyamela, Namso
- Date: 2019
- Subjects: Suspended sediments -- South Africa -- Inxu River , Sedimentation and deposition -- South Africa -- Inxu River , Watershed management -- South Africa -- Inxu River , Erosion -- South Africa -- Inxu River , Soil erosion -- South Africa -- Inxu River
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72150 , vital:30010
- Description: The excessive deposition and accumulation of suspended sediment leads to the degradation of water resources such as dams and rivers. For the purpose of preserving and protecting these resources, suspended sediment needs to be managed, and its management should be catchment-wide and catchment-specific. This is certainly the case for the eroded Inxu River Catchment, which has been identified as a major contributor of sediment to the planned Lalini Dam on the Tsitsa River (a tributary of the Mzimvubu River). Knowledge of suspended sediment flux and catchment sources will aid the design of relevant strategies to manage suspended sediment production. Suspended sediment flux was determined from sediment samples that were collected using citizen-based monitoring techniques at calendar- and event-based sampling frequency, along with discharges estimated using stage-discharge relationships. Sediment source areas were identified by determining the suspended sediment contribution from major sub-catchments and observing similarities in the characteristics of the sub-catchments that produced the most sediment. The Inxu River Catchment produced 5.5 t/ha/yr between 01 May 2016 and 30 April 2017. When compared to modelled sediment yield (7 t/ha/yr) from Le Roux et al. (2015), modelled output was not far off from the measured results and both measured and modelled results identified similar sediment source areas. Q-SSC relationships observed at the Inxu River Outlet indicated that sediment was eroded from local areas and sub-catchment sediment contribution confirmed that most of the sediment was from the lower Inxu River Catchment. Within this area, the Ncolosi and Qwakele River Sub-catchments were major sediment source areas and were subject to widespread gully erosion. Gully erosion was prominent on gentle slopes, foot slopes and valley-bottoms that have concave slope curvature and lie on the Tarkastad Formation. This Formation is associated with some of the most dispersive soils in the area. Moreover, the catchment is vulnerable to erosion due to cultivation and subsequent land abandonment, continuous grazing and dense rural populations. Other studies in the Mzimvubu catchment identified similar catchment characteristics that contribute to excessive erosion. This study has successfully measured sediment yield and identified areas that should be targeted and prioritised for rehabilitation within the Inxu River Catchment. The findings could be applied to a wider catchment scale. The study has successfully demonstrated the use of citizen-based monitoring and desktop techniques and has also identified some pitfalls of this approach.
- Full Text:
- Date Issued: 2019
The spatial planning of racial residential segregation in King William's Town : 1826-1991
- Authors: Zituta, Heyman Mandlakayise
- Date: 1997
- Subjects: Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:4855 , http://hdl.handle.net/10962/d1005531 , Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
- Description: This study investigates the spatial planning of racial residential segregation in King William's Town, induding its former homeland township of Zwelitsha, from 1826 to 1991. The first settlement in the 'white' King William's Town, Brownlee Mission Station, was established in 1826.The town of King William's Town was developed from this settlement. The racial laws which were applied to segregate blacks nationally and locally came to an end in 1991. Primary sources of information were used to determine whether King William's Town was planned along racial lines and to determine the major role players who formulated and implemented the policy. Key sources were archival material, newspapers, maps, interviews, Deeds Office files and the work of other scholars. The establishment of the towm from its genesis as a mission station and a military base is traced and the effects of this legacy on racial separation is detailed. It was found that racial planning of residential areas in King William's Town had been practised in this small town for a long time (prior to the Group Areas Act). The implementation of this policy was marked by forced removal of blacks from areas which were regarded as being for whites. These predominently African concentrations on the east bank of the Buffalo River were relocated to the west bank which was regarded as a black area.An anomalous incident was discovered in this study namely that these racial removals took place before the central state introduced national policy which compelled all local states to plan their residential areas along ethnic considerations. In parallel with the practice of segregation in King William's Town, the township of Zwelitsha was developed adjacent to the town by the government. As this thesis reveals, the development of Zwelitsha was intimately related to that of King William's Town. The major role players in planning residential areas on racial basis were identified as the municipal Council of King William's Town. They were involved in planning racially segregated areas before and after the Group Areas Act. They (the Council) succeeded in closing all freehold locations in the town (1940) and forced the residents to become their tenants who rented dwellings in the west bank municipal location. There were attempts to incorporate this municipal location into the neighbouring homeland township of Zwelitsha. This move was eventually accomplished when all townships in the vicinity of King William's Town were amalgamated to form King William's Town Transitional Local Council in terms of the Local Government Transition Act of 1994 (Government Gazette No. 15468 of 2nd February 1994).
- Full Text:
- Date Issued: 1997
- Authors: Zituta, Heyman Mandlakayise
- Date: 1997
- Subjects: Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:4855 , http://hdl.handle.net/10962/d1005531 , Apartheid -- South Africa -- King William's Town , City planning -- South Africa -- King William's Town , King William's Town (South Africa) -- History
- Description: This study investigates the spatial planning of racial residential segregation in King William's Town, induding its former homeland township of Zwelitsha, from 1826 to 1991. The first settlement in the 'white' King William's Town, Brownlee Mission Station, was established in 1826.The town of King William's Town was developed from this settlement. The racial laws which were applied to segregate blacks nationally and locally came to an end in 1991. Primary sources of information were used to determine whether King William's Town was planned along racial lines and to determine the major role players who formulated and implemented the policy. Key sources were archival material, newspapers, maps, interviews, Deeds Office files and the work of other scholars. The establishment of the towm from its genesis as a mission station and a military base is traced and the effects of this legacy on racial separation is detailed. It was found that racial planning of residential areas in King William's Town had been practised in this small town for a long time (prior to the Group Areas Act). The implementation of this policy was marked by forced removal of blacks from areas which were regarded as being for whites. These predominently African concentrations on the east bank of the Buffalo River were relocated to the west bank which was regarded as a black area.An anomalous incident was discovered in this study namely that these racial removals took place before the central state introduced national policy which compelled all local states to plan their residential areas along ethnic considerations. In parallel with the practice of segregation in King William's Town, the township of Zwelitsha was developed adjacent to the town by the government. As this thesis reveals, the development of Zwelitsha was intimately related to that of King William's Town. The major role players in planning residential areas on racial basis were identified as the municipal Council of King William's Town. They were involved in planning racially segregated areas before and after the Group Areas Act. They (the Council) succeeded in closing all freehold locations in the town (1940) and forced the residents to become their tenants who rented dwellings in the west bank municipal location. There were attempts to incorporate this municipal location into the neighbouring homeland township of Zwelitsha. This move was eventually accomplished when all townships in the vicinity of King William's Town were amalgamated to form King William's Town Transitional Local Council in terms of the Local Government Transition Act of 1994 (Government Gazette No. 15468 of 2nd February 1994).
- Full Text:
- Date Issued: 1997
The sedimentology and palaeoenvironmental significance of vlei sediments on the Winterberg range, South Africa
- Authors: Dewey, Felicity Joy
- Date: 1989
- Subjects: Geology, Stratigraphic -- Holocene Sedimentology Sediments (Geology) -- South Africa -- Eastern Cape -- Winterberg range Geology, Stratigraphic -- Pleistocene Paleoecology -- South Africa -- Eastern Cape -- Winterberg range
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4797 , http://hdl.handle.net/10962/d1001897
- Description: Palaeoenvironmental reconstruction of the late Pleistocene and Holocene geological periods for central and southern Africa has been hampered by the erratic distribution of suitable sites, incomplete and inaccurately dated sequences and the limited nature of published data. One geomorphological feature which has supplied valuable evidence for fluctuations in past environmental conditions, is the vlei or dambo. The type-site of these waterlogged features is in south central Africa, but similar features have been described on other continents. The clastic and organic sediments contained within these features are affected by, and therefore reflect to some degree, the environment under which they were formed. The characteristics of the sediments supply information as to their transport and mechanisms of deposition. From these processes, the environmental conditions at the time of vlei formation can be inferred. The environmental history of the Eastern Cape region has been considerably neglected, and is far less well understood than other countries such as Malawi, Zambia and Zimbabwe. A study site in the Winterberg Range (Eastern Cape) was selected which permitted the comparison of two vleis, the objective being to establish an accurate late Pleistocene sediment chronology for the entire plateau area. Radiocarbon dates from organic layers indicate that these sediments span the last 12 000 years BP, suggesting that organic accumulation at this site began at roughly the same time as at sites further afield. The vlei sediments are analysed in terms of their morphology, particle slze distribution, and other physical and chemical characteristics. These data facilitate the construction of detailed stratigraphic diagrams and a chronological summary of sediment accumulation, from which the period and governing processes of vlei development under changing environments may be described. It is found that the Winterberg vleis contain sediments which respond to changes in the prevailing environment. This makes these sediments useful indices from which to trace such changes during the late Pleistocene and Holocene times. These features are found to be similar in many respects to those described elsewhere in Southern Africa. The study attempts to provide greater understanding of contemporary vlei processes and emphasises the necessity of their preservation, as finite and valuable resources, by future generations
- Full Text:
- Date Issued: 1989
- Authors: Dewey, Felicity Joy
- Date: 1989
- Subjects: Geology, Stratigraphic -- Holocene Sedimentology Sediments (Geology) -- South Africa -- Eastern Cape -- Winterberg range Geology, Stratigraphic -- Pleistocene Paleoecology -- South Africa -- Eastern Cape -- Winterberg range
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4797 , http://hdl.handle.net/10962/d1001897
- Description: Palaeoenvironmental reconstruction of the late Pleistocene and Holocene geological periods for central and southern Africa has been hampered by the erratic distribution of suitable sites, incomplete and inaccurately dated sequences and the limited nature of published data. One geomorphological feature which has supplied valuable evidence for fluctuations in past environmental conditions, is the vlei or dambo. The type-site of these waterlogged features is in south central Africa, but similar features have been described on other continents. The clastic and organic sediments contained within these features are affected by, and therefore reflect to some degree, the environment under which they were formed. The characteristics of the sediments supply information as to their transport and mechanisms of deposition. From these processes, the environmental conditions at the time of vlei formation can be inferred. The environmental history of the Eastern Cape region has been considerably neglected, and is far less well understood than other countries such as Malawi, Zambia and Zimbabwe. A study site in the Winterberg Range (Eastern Cape) was selected which permitted the comparison of two vleis, the objective being to establish an accurate late Pleistocene sediment chronology for the entire plateau area. Radiocarbon dates from organic layers indicate that these sediments span the last 12 000 years BP, suggesting that organic accumulation at this site began at roughly the same time as at sites further afield. The vlei sediments are analysed in terms of their morphology, particle slze distribution, and other physical and chemical characteristics. These data facilitate the construction of detailed stratigraphic diagrams and a chronological summary of sediment accumulation, from which the period and governing processes of vlei development under changing environments may be described. It is found that the Winterberg vleis contain sediments which respond to changes in the prevailing environment. This makes these sediments useful indices from which to trace such changes during the late Pleistocene and Holocene times. These features are found to be similar in many respects to those described elsewhere in Southern Africa. The study attempts to provide greater understanding of contemporary vlei processes and emphasises the necessity of their preservation, as finite and valuable resources, by future generations
- Full Text:
- Date Issued: 1989
The role of salinity as an abiotic driver of ecological condition in a rural agricultural catchment
- Authors: Lerotholi, Sekhonyana
- Date: 2006
- Subjects: Soils, Salts in -- South Africa -- Kat River , Water salinization -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , Salinization -- Control -- South Africa -- Kat River , Agricultural pollution -- South Africa -- Kat River , Aquatic ecology -- South Africa -- Kat River , Salinity -- South Africa -- Kat River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4852 , http://hdl.handle.net/10962/d1005528 , Soils, Salts in -- South Africa -- Kat River , Water salinization -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , Salinization -- Control -- South Africa -- Kat River , Agricultural pollution -- South Africa -- Kat River , Aquatic ecology -- South Africa -- Kat River , Salinity -- South Africa -- Kat River
- Description: The Kat River is an agricultural catchment that drains salt rich geology. Potential salinity impacts on ecological condition of the river were investigated. Monthly salt concentrations and flow discharges were monitored at ten sites along the Kat River below the Kat Dam. Monthly salt loads were computed to relate salinity to land use and ionic data used to assess the toxicity of major salts using the TIMS model. Concentration duration curves for sodium chloride were derived from flow concentration relationships, representing sodium chloride concentrations to which the aquatic ecosystem had been exposed. The ecological condition was assessed at nineteen sites using SASS5 biotic index over four seasons. Finally, the modelled instream salt concentrations and bioasessments were evaluated in terms of the modelled level of species protection afforded at different salt concentrations. Species Sensitivity Distributions (SSDs) were used for this exercise. There was a general downstream increase in salinity with the minimum concentrations recorded at the Fairbain tributary (84 mg/L) and maximum levels at the sewage outfall in Fort Beaufort (1222 mg/L). There was evidence that citrus irrigation upstream of Fort Beaufort increased salinisation. Sodium chloride, and to a lesser extent magnesium sulphate, were the dominant salts in the Kat River catchment, with the latter being more toxic. However these had little or no impact on the aquatic ecosystem. Flow-derived sodium chloride concentrations showed that both the Balfour and Blinkwater tributaries were in a fair/ poor condition. However with regard to ecological condition, it was demonstrated that the river is generally in a good state except for the Blinkwater River and the lower catchment. Degraded habitat condition at the Blinkwater was responsible for poor ecological condition. Integrating SSD derived classes, sodium chloride classes and ecological condition indicated that sodium chloride is a driver of ecological condition at the sewage treatment works and the subsequent site (only two of nineteen biomonitoring sites).
- Full Text:
- Date Issued: 2006
- Authors: Lerotholi, Sekhonyana
- Date: 2006
- Subjects: Soils, Salts in -- South Africa -- Kat River , Water salinization -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , Salinization -- Control -- South Africa -- Kat River , Agricultural pollution -- South Africa -- Kat River , Aquatic ecology -- South Africa -- Kat River , Salinity -- South Africa -- Kat River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4852 , http://hdl.handle.net/10962/d1005528 , Soils, Salts in -- South Africa -- Kat River , Water salinization -- South Africa -- Kat River , Water quality -- South Africa -- Kat River , Salinization -- Control -- South Africa -- Kat River , Agricultural pollution -- South Africa -- Kat River , Aquatic ecology -- South Africa -- Kat River , Salinity -- South Africa -- Kat River
- Description: The Kat River is an agricultural catchment that drains salt rich geology. Potential salinity impacts on ecological condition of the river were investigated. Monthly salt concentrations and flow discharges were monitored at ten sites along the Kat River below the Kat Dam. Monthly salt loads were computed to relate salinity to land use and ionic data used to assess the toxicity of major salts using the TIMS model. Concentration duration curves for sodium chloride were derived from flow concentration relationships, representing sodium chloride concentrations to which the aquatic ecosystem had been exposed. The ecological condition was assessed at nineteen sites using SASS5 biotic index over four seasons. Finally, the modelled instream salt concentrations and bioasessments were evaluated in terms of the modelled level of species protection afforded at different salt concentrations. Species Sensitivity Distributions (SSDs) were used for this exercise. There was a general downstream increase in salinity with the minimum concentrations recorded at the Fairbain tributary (84 mg/L) and maximum levels at the sewage outfall in Fort Beaufort (1222 mg/L). There was evidence that citrus irrigation upstream of Fort Beaufort increased salinisation. Sodium chloride, and to a lesser extent magnesium sulphate, were the dominant salts in the Kat River catchment, with the latter being more toxic. However these had little or no impact on the aquatic ecosystem. Flow-derived sodium chloride concentrations showed that both the Balfour and Blinkwater tributaries were in a fair/ poor condition. However with regard to ecological condition, it was demonstrated that the river is generally in a good state except for the Blinkwater River and the lower catchment. Degraded habitat condition at the Blinkwater was responsible for poor ecological condition. Integrating SSD derived classes, sodium chloride classes and ecological condition indicated that sodium chloride is a driver of ecological condition at the sewage treatment works and the subsequent site (only two of nineteen biomonitoring sites).
- Full Text:
- Date Issued: 2006
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:
- Date Issued: 2021-04
- 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:
- Date Issued: 2021-04
The response of the two interrelated river components, geomorphology and riparian vegetation, to interbasin water transfers in the Orange-Fish-Sundays River Interbasin Transfer Scheme
- Authors: du Plessis, A J E
- Date: 2000
- Subjects: Skoenmakers River (South Africa) , Riparian ecology -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4850 , http://hdl.handle.net/10962/d1005526
- Description: The Skoenmakers River (located in the semi-arid Karoo region of the Eastern Cape) is being used as a transfer route for water transferred by the Orange-Fish-Sundays River Interbasin Transfer Scheme. The change in the hydrological regime of this once ephemeral stream to a much bigger perennial river led to dramatic changes to both the physical structure and riparian vegetation structure of the river system. These changes differ for each of the three river sections, the upper,middle and lower reaches. Qualitative, descriptive geomorphological data was gathered by means of field observations and this was then compared to the quantitative data collected by means of surveyed cross-sectional profiles at selected sites along the length of both the regulated Skoenmakers River and a nonregulated tributary of equivalent size, the Volkers River. Riparian vegetation data was gathered by means of plot sampling along belt transects at each site. A qualitative assessment of the vegetation conditions was also made at each site and then added to the quantitative data from the plot sampling. At each site the different morphological units were identified along the cross-section and changes in the vegetation and sediment composition were recorded. Aerial photographs were used as additional sources of data and observations made from these were compared to data gathered in the field. The pre-IBT channel in this river section was formed by low frequency flood flows but the hydrological regime has now been converted to base flows much higher than normal flood flows. Severe incision, erosion and degradation of both the channel bed and banks occurred. In the lower reaches, post-IBT base flows are lower than pre-IBT flood flows and, due to the increased catchment area, the impact of the IBT was better ‘absorbed’ by the river system. Aggradation and deposition increased for the regulated river in comparison to the non-regulated river due to more sediment introduced The IBT had the greatest impact in the upper reaches of the regulated river due to more sediment introduced at the top of the system.
- Full Text:
- Date Issued: 2000
- Authors: du Plessis, A J E
- Date: 2000
- Subjects: Skoenmakers River (South Africa) , Riparian ecology -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4850 , http://hdl.handle.net/10962/d1005526
- Description: The Skoenmakers River (located in the semi-arid Karoo region of the Eastern Cape) is being used as a transfer route for water transferred by the Orange-Fish-Sundays River Interbasin Transfer Scheme. The change in the hydrological regime of this once ephemeral stream to a much bigger perennial river led to dramatic changes to both the physical structure and riparian vegetation structure of the river system. These changes differ for each of the three river sections, the upper,middle and lower reaches. Qualitative, descriptive geomorphological data was gathered by means of field observations and this was then compared to the quantitative data collected by means of surveyed cross-sectional profiles at selected sites along the length of both the regulated Skoenmakers River and a nonregulated tributary of equivalent size, the Volkers River. Riparian vegetation data was gathered by means of plot sampling along belt transects at each site. A qualitative assessment of the vegetation conditions was also made at each site and then added to the quantitative data from the plot sampling. At each site the different morphological units were identified along the cross-section and changes in the vegetation and sediment composition were recorded. Aerial photographs were used as additional sources of data and observations made from these were compared to data gathered in the field. The pre-IBT channel in this river section was formed by low frequency flood flows but the hydrological regime has now been converted to base flows much higher than normal flood flows. Severe incision, erosion and degradation of both the channel bed and banks occurred. In the lower reaches, post-IBT base flows are lower than pre-IBT flood flows and, due to the increased catchment area, the impact of the IBT was better ‘absorbed’ by the river system. Aggradation and deposition increased for the regulated river in comparison to the non-regulated river due to more sediment introduced The IBT had the greatest impact in the upper reaches of the regulated river due to more sediment introduced at the top of the system.
- Full Text:
- Date Issued: 2000
The remote sensing of fires and their effects on soil properties in the uKhahlamba Drakensberg Park
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
The relationship between daily and monthly pan evaporation and rainfall totals in Southern Africa
- Authors: Watkins, Deidre Ann
- Date: 1994
- Subjects: Evaporation (Meteorology) -- South Africa , Rain and rainfall -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4849 , http://hdl.handle.net/10962/d1005525 , Evaporation (Meteorology) -- South Africa , Rain and rainfall -- South Africa
- Description: Recent droughts in South Africa have highlighted the vulnerability of the economy to water restrictions. However, the degree of surface aridity in southern Africa is not only a function of precipitation, but also one of evaporation. The quantitative assessment of evaporative loss is important since it is a major component of the water budget. For example, in southern Africa, evaporation accounts for 79.5% of the hydrological water budget. As the cost of water resource development increases, so there has been an increasing demand for hydrological modelling to optimise project planning. Reliable estimates of evaporation are essential to significant improvements in the practice of hydrology and particularly in a country like South Africa which is prone to the adverse effects of drought. It is difficult to adequately measure potential evaporation over an area as large and as sparsely populated as southern Africa. Despite the research that has been undertaken to estimate evaporation from related meteorological and physical variables, generally, the estimation of evaporation in southern Africa has been unsatisfactory. There are a number of methods for estimating potential evaporation. However, a major problem tends to be the incompatibility between the data requirements of some of the more physically-based models, and the actual data that is available and collected on a routine basis at a sufficient number of stations. In existing water resources estimation models, evaporation is often incorporated as a time series input of pan evaporation, using daily or monthly values. The lack of a nearby record of pan evaporation often necessitates the use of published regionalised mean monthly pan values. This technique of using the mean monthly evaporation values in water resources estimation models tends to overestimate or underestimate the actual evaporation that is occurring, depending on the actual amount of rain occurring in a specific month. This is because no attempt has been made to correct these mean evaporation values for the amount of rainfall that occurs in a specific month, in a specific region. The regional rainfall/evaporation relationships (that vary spatially and temporally) are not taken into account. A need was identified for an assessment of the value of grouping data by rainfall as a better tool for estimating evaporation. Here, the monthly evaporation and the mean monthly evaporation for a specific rainfall group category will be estimated using daily data. Due to data availability, the most appropriate time scale to use is one day. Therefore, in this study an attempt has been made to relate rainfall amounts to evaporation values and to develop rainfall/evaporation relationships, identifying variations by season and region. It is important to identify and quantify these relationships and assess the possibility of incorporating these variations into existing Water Resource Estimation Models. The ability to derive and develop meaningful relationships between daily rainfall and daily evaporation for each season, and for a number of sites considered representative of the climatological zones for southern Africa was assessed. The first approach was to compare daily evaporation plotted against daily rainfall, and in the process develop a quantitative rainfall/evaporation relationship. Unfortunately, no direct linear relationships were identified. The second approach was to test the performance of the water resource estimation model using the following possible choices, (i) a real daily input (COREVAP1) - here the estimated monthly evaporation is the sum of the product number of days within each month * mean daily evaporation for each specified raingroup category, (ii) a distributed mean monthly input (COREVAP2) - here evaporation is estimated using a random sampling procedure to draw samples from a restricted part of the daily evaporation distribution for each raingroup and is defined by the mean and standard deviation, and (iii) a distributed mean monthly input and correction (COREVAP3) - here samples are drawn from the full distribution of daily evaporation for each raingroup category. The performance of the COREVAP programs was analyzed in terms of the improvement effected by estimating evaporation using the mean monthly evaporation regardless of rain. COREVAP1 produced the best simulations of monthly evaporation. This was expected as the program uses the straight-forward mean evaporation value multiplied by the number of days to simulate the monthly evaporation values. However, the COREVAP programs did not perform well when using the monthly evaporation data based on daily infilled values using the transformed parameters. Any regionalisation of parameter files would mean that a range of parameters in a region would now be represented by a single value. The need to assess the effect of this change from a regional range of values to a single representative value was identified. This was done by conducting a sensitivity analysis, in terms of what effect a percentage increase or decrease in the lambda, mean evaporation and mean rainfall values would have on the resultant simulated monthly evaporation and coefficient of efficiency values. A sensitivity analysis was conducted on COREVAP1 to determine which parameters of the model had the greatest influence on the simulations. This was done with reference to the percentage error of monthly evaporation and the monthly and accumulative coefficient of efficiency values. Generally, the percentage increase/decrease in mean evaporation values that are acceptable for the representative stations are low. In contrast, fairly high percentage changes in mean rainfall values are tolerated. The objective of the regionalisation of parameters was to determine whether general characteristics can be applied to some stations that are significantly different compared to other stations, so that the stations may be combined to represent a separate region. The demarcation of regions was conducted on the basis of the regional relative mean evaporation values (per raingroup, per season), the daily mean evaporation values per month and the average number of days within each raingroup, per season. Intra-station and inter-region variability was analysed using the Kruskal-Wallis H test and the Friedman Fr test. The regional parameters were then used as input into the COREVAP programs and the simulation results were analysed in terms of whether the simulations still produce positive accumulative coefficient of efficiency values. The results obtained when substituting the regional parameters were not good. Based on these results, it has been concluded that the hypothesis that grouping data by rainfall may be a better tool for estimating evaporation compared to simply using the mean monthly evaporation, may be rejected.
- Full Text:
- Date Issued: 1994
- Authors: Watkins, Deidre Ann
- Date: 1994
- Subjects: Evaporation (Meteorology) -- South Africa , Rain and rainfall -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4849 , http://hdl.handle.net/10962/d1005525 , Evaporation (Meteorology) -- South Africa , Rain and rainfall -- South Africa
- Description: Recent droughts in South Africa have highlighted the vulnerability of the economy to water restrictions. However, the degree of surface aridity in southern Africa is not only a function of precipitation, but also one of evaporation. The quantitative assessment of evaporative loss is important since it is a major component of the water budget. For example, in southern Africa, evaporation accounts for 79.5% of the hydrological water budget. As the cost of water resource development increases, so there has been an increasing demand for hydrological modelling to optimise project planning. Reliable estimates of evaporation are essential to significant improvements in the practice of hydrology and particularly in a country like South Africa which is prone to the adverse effects of drought. It is difficult to adequately measure potential evaporation over an area as large and as sparsely populated as southern Africa. Despite the research that has been undertaken to estimate evaporation from related meteorological and physical variables, generally, the estimation of evaporation in southern Africa has been unsatisfactory. There are a number of methods for estimating potential evaporation. However, a major problem tends to be the incompatibility between the data requirements of some of the more physically-based models, and the actual data that is available and collected on a routine basis at a sufficient number of stations. In existing water resources estimation models, evaporation is often incorporated as a time series input of pan evaporation, using daily or monthly values. The lack of a nearby record of pan evaporation often necessitates the use of published regionalised mean monthly pan values. This technique of using the mean monthly evaporation values in water resources estimation models tends to overestimate or underestimate the actual evaporation that is occurring, depending on the actual amount of rain occurring in a specific month. This is because no attempt has been made to correct these mean evaporation values for the amount of rainfall that occurs in a specific month, in a specific region. The regional rainfall/evaporation relationships (that vary spatially and temporally) are not taken into account. A need was identified for an assessment of the value of grouping data by rainfall as a better tool for estimating evaporation. Here, the monthly evaporation and the mean monthly evaporation for a specific rainfall group category will be estimated using daily data. Due to data availability, the most appropriate time scale to use is one day. Therefore, in this study an attempt has been made to relate rainfall amounts to evaporation values and to develop rainfall/evaporation relationships, identifying variations by season and region. It is important to identify and quantify these relationships and assess the possibility of incorporating these variations into existing Water Resource Estimation Models. The ability to derive and develop meaningful relationships between daily rainfall and daily evaporation for each season, and for a number of sites considered representative of the climatological zones for southern Africa was assessed. The first approach was to compare daily evaporation plotted against daily rainfall, and in the process develop a quantitative rainfall/evaporation relationship. Unfortunately, no direct linear relationships were identified. The second approach was to test the performance of the water resource estimation model using the following possible choices, (i) a real daily input (COREVAP1) - here the estimated monthly evaporation is the sum of the product number of days within each month * mean daily evaporation for each specified raingroup category, (ii) a distributed mean monthly input (COREVAP2) - here evaporation is estimated using a random sampling procedure to draw samples from a restricted part of the daily evaporation distribution for each raingroup and is defined by the mean and standard deviation, and (iii) a distributed mean monthly input and correction (COREVAP3) - here samples are drawn from the full distribution of daily evaporation for each raingroup category. The performance of the COREVAP programs was analyzed in terms of the improvement effected by estimating evaporation using the mean monthly evaporation regardless of rain. COREVAP1 produced the best simulations of monthly evaporation. This was expected as the program uses the straight-forward mean evaporation value multiplied by the number of days to simulate the monthly evaporation values. However, the COREVAP programs did not perform well when using the monthly evaporation data based on daily infilled values using the transformed parameters. Any regionalisation of parameter files would mean that a range of parameters in a region would now be represented by a single value. The need to assess the effect of this change from a regional range of values to a single representative value was identified. This was done by conducting a sensitivity analysis, in terms of what effect a percentage increase or decrease in the lambda, mean evaporation and mean rainfall values would have on the resultant simulated monthly evaporation and coefficient of efficiency values. A sensitivity analysis was conducted on COREVAP1 to determine which parameters of the model had the greatest influence on the simulations. This was done with reference to the percentage error of monthly evaporation and the monthly and accumulative coefficient of efficiency values. Generally, the percentage increase/decrease in mean evaporation values that are acceptable for the representative stations are low. In contrast, fairly high percentage changes in mean rainfall values are tolerated. The objective of the regionalisation of parameters was to determine whether general characteristics can be applied to some stations that are significantly different compared to other stations, so that the stations may be combined to represent a separate region. The demarcation of regions was conducted on the basis of the regional relative mean evaporation values (per raingroup, per season), the daily mean evaporation values per month and the average number of days within each raingroup, per season. Intra-station and inter-region variability was analysed using the Kruskal-Wallis H test and the Friedman Fr test. The regional parameters were then used as input into the COREVAP programs and the simulation results were analysed in terms of whether the simulations still produce positive accumulative coefficient of efficiency values. The results obtained when substituting the regional parameters were not good. Based on these results, it has been concluded that the hypothesis that grouping data by rainfall may be a better tool for estimating evaporation compared to simply using the mean monthly evaporation, may be rejected.
- Full Text:
- Date Issued: 1994
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:
- Date Issued: 2022-10-14
- 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:
- Date Issued: 2022-10-14
The origin of bedrock depression wetlands in the southern Cape of South Africa: a changing perspective
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
- Authors: Ellery, Steven
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Geomorphology -- South Africa -- Eastern Cape , Physical geography -- South Africa -- Eastern Cape , Erosion -- South Africa -- Eastern Cape , Evolutionary paleoecology -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/67833 , vital:29152
- Description: The predominant theory of the origin of depression wetlands in southern Africa was developed by Goudie and Thomas (1985) and focuses primarily on mechanisms relating to deflation and erosion as the main drivers of wetland formation. This theory is based on wind driven deflation of animal watering areas where heavy grazing and trampling of vegetation promotes removal of sediment over short periods of time by wind, to create local depressions and impoundment of water. However, this theory applies in arid and semi-arid areas where grazing can reduce vegetation sufficiently to lead to deflation but does not fully explain the origins of depression wetlands that have formed in moist climates or on ancient erosion surfaces such as the African Erosion Surface (AES). This study investigates the origin of a depression wetland that has formed on sandstone bedrock through weathering and dissolution on the AES in South Africa. Wetlands like this act as groundwater recharge zones such that water flows away from the centre of the depression, taking with it any dissolved solutes derived from weathering of the bed of the depression. Fluctuations between wet and dry periods create both highly reducing conditions (during wet phases) and highly oxidising conditions (during dry phases) beneath the margins of these depression wetlands. Some of the main constituents of the sandstone in this wetland are iron(III) oxides, which are highly sensitive to redox conditions and have therefore been transported to and trapped in the margins of the depression. The redistribution of iron(III) oxides from the centre towards the margins of the depression has caused a net volume loss in the centre of the depression, causing sagging, and a net volume gain at the margins of the depression associated with swelling. This process occurs over periods upwards of a million years and explains the presence of depression wetlands in moist climates.
- Full Text:
- Date Issued: 2019
The morphology and sedimentology of two unconsolidated quaternary debris slope deposits in the Alexandria district, Cape Province
- Authors: Illgner, Peter Mark
- Date: 1995
- Subjects: Slopes (Physical geography) -- South Africa , Weathering -- South Africa , Geomorphology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4843 , http://hdl.handle.net/10962/d1005519
- Description: Research on hillslope surface processes and hillslope stratigraphy has been neglected in southern Africa. The amount of published literature on hillslope stratigraphy in southern Africa is very limited. Hillslope sediments provide a record of past environmental conditions and may be especially useful in calculating the recurrence interval of extreme environmental conditions such as earthquakes and intense rainfall events. The characteristics of hillslope sediments provide information as to their origin, transport and mechanisms of deposition. No published work could be found that had been undertaken on hillslope surface processes or stratigraphy in the eastern Cape coastal region. This study attempted to fill this gap in the geomorphic literature for southern Africa. The surface processes acting on hillslopes at Burchleigh and Spring Grove in the Alexandria district of the eastern Cape were examined in terms of slope morphology, surface sediment characteristics and the internal geometry of the hillslope sedimentary deposits. The late Quaternary hillslope sedimentary deposits at the two study sites are composed of fine grained colluvial sediments intercalated with highly lenticular diamicts. The fine grained colluvial sediments were emplaced by overland flow processes while the diamicts were deposited by debris flows. The sedimentary sequences at both study sites have a basal conglomerate interpreted as a channel lag deposit. Most slope failures preceding debris flow events were probably triggered by intense or extended periods of rainfall associated with cold fronts or cut-of flows. Seismic events may also have triggered slope failure, with or without the hillslope sediments being saturated. The results of this study indicate that a continuum exists between the slopewash dominated processes of the presently summer rainfall regions of Natal to the present winter rainfall regions of the western Cape where mass movement processes are significant. Hillslope deposits, therefore, provide a record of environmental conditions which may greatly facilitate proper management of the landscape.
- Full Text:
- Date Issued: 1995
- Authors: Illgner, Peter Mark
- Date: 1995
- Subjects: Slopes (Physical geography) -- South Africa , Weathering -- South Africa , Geomorphology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4843 , http://hdl.handle.net/10962/d1005519
- Description: Research on hillslope surface processes and hillslope stratigraphy has been neglected in southern Africa. The amount of published literature on hillslope stratigraphy in southern Africa is very limited. Hillslope sediments provide a record of past environmental conditions and may be especially useful in calculating the recurrence interval of extreme environmental conditions such as earthquakes and intense rainfall events. The characteristics of hillslope sediments provide information as to their origin, transport and mechanisms of deposition. No published work could be found that had been undertaken on hillslope surface processes or stratigraphy in the eastern Cape coastal region. This study attempted to fill this gap in the geomorphic literature for southern Africa. The surface processes acting on hillslopes at Burchleigh and Spring Grove in the Alexandria district of the eastern Cape were examined in terms of slope morphology, surface sediment characteristics and the internal geometry of the hillslope sedimentary deposits. The late Quaternary hillslope sedimentary deposits at the two study sites are composed of fine grained colluvial sediments intercalated with highly lenticular diamicts. The fine grained colluvial sediments were emplaced by overland flow processes while the diamicts were deposited by debris flows. The sedimentary sequences at both study sites have a basal conglomerate interpreted as a channel lag deposit. Most slope failures preceding debris flow events were probably triggered by intense or extended periods of rainfall associated with cold fronts or cut-of flows. Seismic events may also have triggered slope failure, with or without the hillslope sediments being saturated. The results of this study indicate that a continuum exists between the slopewash dominated processes of the presently summer rainfall regions of Natal to the present winter rainfall regions of the western Cape where mass movement processes are significant. Hillslope deposits, therefore, provide a record of environmental conditions which may greatly facilitate proper management of the landscape.
- Full Text:
- Date Issued: 1995
The influence of landscape dis-connectivity on the structure and function of the Krom River, Eastern Cape, South Africa
- Authors: McNamara, Shaun
- Date: 2018
- Subjects: Wetland ecology -- South Africa -- Kromme River (Eastern Cape) , Alluvial fans -- South Africa -- Kromme River (Eastern Cape) , Sedimentation and deposition -- South Africa -- Kromme River (Eastern Cape) , Fluvial geomorphology -- South Africa -- Kromme River (Eastern Cape) , Soil erosion -- South Africa -- Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63198 , vital:28380
- Description: Given that a broad valley and low longitudinal slope are important pre-requisites for wetland formation in dryland environments, it has been proposed that cut-and-fill cycles are largely responsible for the geomorphic evolution of the Krom River valley-bottom wetlands. Research to support this suggestion has focused extensively on the role of phases of incision. As a result, little is known about where sediment mobilised during phases of incision is being deposited (filling phase). This study aimed to address this question to add to the understanding of how cut-and-fill cycles influence the structure and functioning of the Krom River and its wetlands. This was achieved through a reach-scale appraisal of the degree of longitudinal connectivity of the Krom River. The reach used for this appraisal contained an incised section along which the river channel exists as a large gully, and a section immediately downstream of the gully terminus where the Krom River is un-gullied, and flow is diffuse across most of the width of the valley floor. Quantification of the masses of sediment eroded and deposited within the selected reach of the Krom River during a single recent (2012) flood event revealed that the degree of longitudinal connectivity in the Krom River is generally low. During the flood, much of the sediment mobilised by the cutting of the Krom River channel was deposited immediately downstream of the gully terminus, forming a large floodout feature. Particle size analyses of core samples taken along the floodout feature showed that the coarsest fraction of previously mobilised sediment was deposited at the head of the floodout, while finer sediment fractions were deposited progressively further downstream. Field surveys revealed that the pattern of deposition within the floodout feature led to localised steepening of the studied reach of the Krom River downstream of the gully terminus. Surveys of the recently eroded gully revealed that following incision, the eroded stream bed had a lower longitudinal gradient than both the pre-erosional land surface and the regional slope of the Krom River. The results of this study suggest that floodout formation downstream of gullies may promote the transgression of geomorphic thresholds for erosion, such that the development of floodout features leads to likely initiation of new cutting phases in novel locations along the course of the Krom River. They further suggest that the Krom River is capable of intrinsic longitudinal self-recovery through ongoing cut-and-fill cycles. Finally, it would appear that the current cutting phases responsible for the “destruction” of wetlands within the system are part of a cycle that will lead to prolonged geomorphic stability, such that the system is made more suitable for the long-term re-establishment of wetlands.
- Full Text:
- Date Issued: 2018
- Authors: McNamara, Shaun
- Date: 2018
- Subjects: Wetland ecology -- South Africa -- Kromme River (Eastern Cape) , Alluvial fans -- South Africa -- Kromme River (Eastern Cape) , Sedimentation and deposition -- South Africa -- Kromme River (Eastern Cape) , Fluvial geomorphology -- South Africa -- Kromme River (Eastern Cape) , Soil erosion -- South Africa -- Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63198 , vital:28380
- Description: Given that a broad valley and low longitudinal slope are important pre-requisites for wetland formation in dryland environments, it has been proposed that cut-and-fill cycles are largely responsible for the geomorphic evolution of the Krom River valley-bottom wetlands. Research to support this suggestion has focused extensively on the role of phases of incision. As a result, little is known about where sediment mobilised during phases of incision is being deposited (filling phase). This study aimed to address this question to add to the understanding of how cut-and-fill cycles influence the structure and functioning of the Krom River and its wetlands. This was achieved through a reach-scale appraisal of the degree of longitudinal connectivity of the Krom River. The reach used for this appraisal contained an incised section along which the river channel exists as a large gully, and a section immediately downstream of the gully terminus where the Krom River is un-gullied, and flow is diffuse across most of the width of the valley floor. Quantification of the masses of sediment eroded and deposited within the selected reach of the Krom River during a single recent (2012) flood event revealed that the degree of longitudinal connectivity in the Krom River is generally low. During the flood, much of the sediment mobilised by the cutting of the Krom River channel was deposited immediately downstream of the gully terminus, forming a large floodout feature. Particle size analyses of core samples taken along the floodout feature showed that the coarsest fraction of previously mobilised sediment was deposited at the head of the floodout, while finer sediment fractions were deposited progressively further downstream. Field surveys revealed that the pattern of deposition within the floodout feature led to localised steepening of the studied reach of the Krom River downstream of the gully terminus. Surveys of the recently eroded gully revealed that following incision, the eroded stream bed had a lower longitudinal gradient than both the pre-erosional land surface and the regional slope of the Krom River. The results of this study suggest that floodout formation downstream of gullies may promote the transgression of geomorphic thresholds for erosion, such that the development of floodout features leads to likely initiation of new cutting phases in novel locations along the course of the Krom River. They further suggest that the Krom River is capable of intrinsic longitudinal self-recovery through ongoing cut-and-fill cycles. Finally, it would appear that the current cutting phases responsible for the “destruction” of wetlands within the system are part of a cycle that will lead to prolonged geomorphic stability, such that the system is made more suitable for the long-term re-establishment of wetlands.
- Full Text:
- Date Issued: 2018
The influence of Acacia Mearnsii invasion on soil properties in the Kouga Mountains, Eastern Cape, South Africa
- Van der Waal, Benjamin Wentsel
- Authors: Van der Waal, Benjamin Wentsel
- Date: 2010
- Subjects: Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4839 , http://hdl.handle.net/10962/d1005515 , Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Description: The invasion of Acacia mearnsii in the Kouga catchment, Eastern Cape, South Africa, has various negative impacts on the ecosystem. These impacts include: reduced species richness, increased water use, increased nutrients and increased N cycling rates. The native shrubby fynbos vegetation has adapted to the acidic nutrient poor soils and Mediterranean climate of the Kouga Mountains. Fynbos, however, is currently being out competed by the much taller Acacia mearnsii trees, due to their competitive nature and ability to fix nitrogen, thereby enriching the soil. The invaded sections of the valley bottoms and lower hill slopes are characterised by an almost complete monoculture of Acacia mearnsii, with very few fynbos species still present. The Department of Water and Environmental Affairs sponsored Working for Water programme started clearing Acacia mearnsii in 1996 in the Kouga Mountains. Cleared sites have remained bare for long periods, indicating that soil properties are not favourable for indigenous propagule re-establishment. The aim of this research was to assess how A. mearnsii invasion and clearing affect fynbos recovery through its impact on soils. This was done by characterising vegetation and soil properties on fynbos, infested and cleared slopes. Vegetation cover for various growth forms was determined and a species list was compiled for each plot. The slope angle, surface hardness, litter cover, bare ground cover and soil depth were measured in the field, whereas water repellency, particle size and the chemical composition were measured in the laboratory. Furthermore, the plant establishment capacity of soils from fynbos, infested and cleared slopes was calculated. This was done by germinating fynbos seeds and growing fynbos plants in soils from the various slopes. The effect that invasion and clearing has on soil erosion was quantified using erosion plots on fynbos, infested and cleared slopes. The invasion and clearing of Acacia mearnsii led to an increase in soil nutrients, especially nitrogen, phosphorus, potassium, carbon and manganese. Furthermore, soils became more acidic, with increased water repellency and reduced surface hardness. The vegetation changed to a tree-dominated structure, replacing the native species. Native plant germination was relatively unaffected by invasion and clearing, with an increase in germination just after clearing. Plant growth of a native grass, Themeda triandra, and herb, Helichrysum umbraculigerum, has increased on soils from cleared slopes. This study showed that soil movement increased on slopes which are invaded and cleared of Acacia mearnsii, with erosion rates doubling on invaded slopes
- Full Text:
- Date Issued: 2010
- Authors: Van der Waal, Benjamin Wentsel
- Date: 2010
- Subjects: Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4839 , http://hdl.handle.net/10962/d1005515 , Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Description: The invasion of Acacia mearnsii in the Kouga catchment, Eastern Cape, South Africa, has various negative impacts on the ecosystem. These impacts include: reduced species richness, increased water use, increased nutrients and increased N cycling rates. The native shrubby fynbos vegetation has adapted to the acidic nutrient poor soils and Mediterranean climate of the Kouga Mountains. Fynbos, however, is currently being out competed by the much taller Acacia mearnsii trees, due to their competitive nature and ability to fix nitrogen, thereby enriching the soil. The invaded sections of the valley bottoms and lower hill slopes are characterised by an almost complete monoculture of Acacia mearnsii, with very few fynbos species still present. The Department of Water and Environmental Affairs sponsored Working for Water programme started clearing Acacia mearnsii in 1996 in the Kouga Mountains. Cleared sites have remained bare for long periods, indicating that soil properties are not favourable for indigenous propagule re-establishment. The aim of this research was to assess how A. mearnsii invasion and clearing affect fynbos recovery through its impact on soils. This was done by characterising vegetation and soil properties on fynbos, infested and cleared slopes. Vegetation cover for various growth forms was determined and a species list was compiled for each plot. The slope angle, surface hardness, litter cover, bare ground cover and soil depth were measured in the field, whereas water repellency, particle size and the chemical composition were measured in the laboratory. Furthermore, the plant establishment capacity of soils from fynbos, infested and cleared slopes was calculated. This was done by germinating fynbos seeds and growing fynbos plants in soils from the various slopes. The effect that invasion and clearing has on soil erosion was quantified using erosion plots on fynbos, infested and cleared slopes. The invasion and clearing of Acacia mearnsii led to an increase in soil nutrients, especially nitrogen, phosphorus, potassium, carbon and manganese. Furthermore, soils became more acidic, with increased water repellency and reduced surface hardness. The vegetation changed to a tree-dominated structure, replacing the native species. Native plant germination was relatively unaffected by invasion and clearing, with an increase in germination just after clearing. Plant growth of a native grass, Themeda triandra, and herb, Helichrysum umbraculigerum, has increased on soils from cleared slopes. This study showed that soil movement increased on slopes which are invaded and cleared of Acacia mearnsii, with erosion rates doubling on invaded slopes
- Full Text:
- Date Issued: 2010
The image of agriculture in two Ciskeian communities
- Authors: Webb, Nigel L
- Date: 1980
- Subjects: Urban agriculture -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Agriculture -- South Africa -- Eastern Cape , Urban agriculture
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:4791 , http://hdl.handle.net/10962/d1001891
- Description: Agriculture is a complex cultural institution. This is particularly the case when studying subsistence conditions in a tribal system, because aspects requiring investigation include social, religious, political and economic factors (Dalton, 1967). These factors represent an extremely broad sphere of inquiry and the large number of relevant aspects has been the cause of problems plaguing attempts to develop subsistence agriculture (Grigg, 1973). The purpose of this study is to outline an environmental perception approach to agriculture and explore the contribution that the approach could make to agricultural improvement. As such it represents a pilot study which attempts to introduce behavioural science research into agricultural development. Foster (et all (1965) outline three research foci in this respect; the socio-cultural-psychological system of the recipient people (farmers), the system of the innovating organization, and the interaction of the two. This study deals with the first focus outlined by Foster, and aims to make a statement about the image that two semi-subsistence communities have of their agricultural system. In other words, how their agricultural system appears to them.
- Full Text:
- Date Issued: 1980
- Authors: Webb, Nigel L
- Date: 1980
- Subjects: Urban agriculture -- Eastern Cape , Land use, Urban -- South Africa -- Eastern Cape , Agriculture -- South Africa -- Eastern Cape , Urban agriculture
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:4791 , http://hdl.handle.net/10962/d1001891
- Description: Agriculture is a complex cultural institution. This is particularly the case when studying subsistence conditions in a tribal system, because aspects requiring investigation include social, religious, political and economic factors (Dalton, 1967). These factors represent an extremely broad sphere of inquiry and the large number of relevant aspects has been the cause of problems plaguing attempts to develop subsistence agriculture (Grigg, 1973). The purpose of this study is to outline an environmental perception approach to agriculture and explore the contribution that the approach could make to agricultural improvement. As such it represents a pilot study which attempts to introduce behavioural science research into agricultural development. Foster (et all (1965) outline three research foci in this respect; the socio-cultural-psychological system of the recipient people (farmers), the system of the innovating organization, and the interaction of the two. This study deals with the first focus outlined by Foster, and aims to make a statement about the image that two semi-subsistence communities have of their agricultural system. In other words, how their agricultural system appears to them.
- Full Text:
- Date Issued: 1980
The hydrogeomorphology of the Featherstone Kloof Catchment
- Authors: Ntakumba, Stanley Sixolile
- Date: 2013-05-29
- Subjects: Wetlands -- South Africa , Wetland restoration -- South Africa -- Featherstone Kloof Catchment , Wetland conservation -- South Africa -- Featherstone Kloof Catchment , Wetland management -- South Africa -- Featherstone Kloof Catchment , Wetland ecology -- South Africa -- Featherstone Kloof Catchment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4870 , http://hdl.handle.net/10962/d1007862 , Wetlands -- South Africa , Wetland restoration -- South Africa -- Featherstone Kloof Catchment , Wetland conservation -- South Africa -- Featherstone Kloof Catchment , Wetland management -- South Africa -- Featherstone Kloof Catchment , Wetland ecology -- South Africa -- Featherstone Kloof Catchment
- Description: Wetlands are an important part of the landscape as hydrogeomorphological ecosystems. Over the centuries their importance has not received relevant attention; instead they have been treated as wastelands impeding development for maximum economic benefits. Research evidence from different parts of the world has influenced the change of such negative perceptions to an extent that the issue of wetlands' rehabilitation/restoration, conservation and management is firmly on the global agenda and local agendas of various countries, as evidenced by the adoption of the Ramsar Convention in 1971, and the Working for Water and Working for Wetlands programmes of the South African government. The aim of this research was to investigate the hydrological and geomorphological functions of a headwater wetland located in the Featherstone Kloof Catchment near Grahamstown, South Africa. The research was based on the hypotheses that wetlands store sediments, attenuate floods, store water and prolong downstream flows. A literature survey was conducted to gauge the state of knowledge about wetlands, particularly their hydrogeomorphology. An attempt was made to locate the study area within the broad historical and spatial context using a number of methods, including the radiocarbon dating of wetland sediments, the review of relevant literature and the analysis of historical hydroclimatic data. The results revealed that the wetland has existed for approximately 2000 years - as the oldest radiocarbon date obtained was 1850±50 BP. An analysis of more than a century (+120 years) long Grahamstown rainfall series indicated a steady fluctuation of rainfall around the mean, with regular decada1 cycles of wet and dry spells. Years with more rain below average were more common than those with higher rainfall, and storms events were quite common in the III area over the period. The distribution of seasons in the area over a calendar year period was demonstrated through the use of evaporation data. An intensive monitoring of hydrological and geomorphological variables was carried out using a combination of methods. The topography of the instrumented site was determined using a Total Station from reference benchmarks. Hydrological measurements included a nest of forty-eight piezometers for water table monitoring, and streamflow gauges at the upstream and downstream limits of the study site. Soil stratigraphic analysis was carried out through field techniques and laboratory measurements. A survey of wetland sediments was carried out after the main floods events. Data generated were used to analyse relationships between various variables and their role on the functioning of the wetland. The water balance of the wetland was quantified. The results indicated that the wetland was able to perform the cited hydrogeomorphological functions to some extent. For example, one of the key findings of this research is that the wetland was important in sustaining base flows under normal circumstances. However, the wetland did little to attenuate large floods. The results also revealed some important questions that require further research, including the role played by extreme flood events in altering wetland characteristics, the contribution of each water balance component in the hydrological functioning of wetlands, and importance of quantifying sediment budgets of headwater wetlands. The study demonstrated the complex nature of the wetland hydro geomorphology and that certain questions about wetlands require direct field monitoring to be better understood. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Authors: Ntakumba, Stanley Sixolile
- Date: 2013-05-29
- Subjects: Wetlands -- South Africa , Wetland restoration -- South Africa -- Featherstone Kloof Catchment , Wetland conservation -- South Africa -- Featherstone Kloof Catchment , Wetland management -- South Africa -- Featherstone Kloof Catchment , Wetland ecology -- South Africa -- Featherstone Kloof Catchment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4870 , http://hdl.handle.net/10962/d1007862 , Wetlands -- South Africa , Wetland restoration -- South Africa -- Featherstone Kloof Catchment , Wetland conservation -- South Africa -- Featherstone Kloof Catchment , Wetland management -- South Africa -- Featherstone Kloof Catchment , Wetland ecology -- South Africa -- Featherstone Kloof Catchment
- Description: Wetlands are an important part of the landscape as hydrogeomorphological ecosystems. Over the centuries their importance has not received relevant attention; instead they have been treated as wastelands impeding development for maximum economic benefits. Research evidence from different parts of the world has influenced the change of such negative perceptions to an extent that the issue of wetlands' rehabilitation/restoration, conservation and management is firmly on the global agenda and local agendas of various countries, as evidenced by the adoption of the Ramsar Convention in 1971, and the Working for Water and Working for Wetlands programmes of the South African government. The aim of this research was to investigate the hydrological and geomorphological functions of a headwater wetland located in the Featherstone Kloof Catchment near Grahamstown, South Africa. The research was based on the hypotheses that wetlands store sediments, attenuate floods, store water and prolong downstream flows. A literature survey was conducted to gauge the state of knowledge about wetlands, particularly their hydrogeomorphology. An attempt was made to locate the study area within the broad historical and spatial context using a number of methods, including the radiocarbon dating of wetland sediments, the review of relevant literature and the analysis of historical hydroclimatic data. The results revealed that the wetland has existed for approximately 2000 years - as the oldest radiocarbon date obtained was 1850±50 BP. An analysis of more than a century (+120 years) long Grahamstown rainfall series indicated a steady fluctuation of rainfall around the mean, with regular decada1 cycles of wet and dry spells. Years with more rain below average were more common than those with higher rainfall, and storms events were quite common in the III area over the period. The distribution of seasons in the area over a calendar year period was demonstrated through the use of evaporation data. An intensive monitoring of hydrological and geomorphological variables was carried out using a combination of methods. The topography of the instrumented site was determined using a Total Station from reference benchmarks. Hydrological measurements included a nest of forty-eight piezometers for water table monitoring, and streamflow gauges at the upstream and downstream limits of the study site. Soil stratigraphic analysis was carried out through field techniques and laboratory measurements. A survey of wetland sediments was carried out after the main floods events. Data generated were used to analyse relationships between various variables and their role on the functioning of the wetland. The water balance of the wetland was quantified. The results indicated that the wetland was able to perform the cited hydrogeomorphological functions to some extent. For example, one of the key findings of this research is that the wetland was important in sustaining base flows under normal circumstances. However, the wetland did little to attenuate large floods. The results also revealed some important questions that require further research, including the role played by extreme flood events in altering wetland characteristics, the contribution of each water balance component in the hydrological functioning of wetlands, and importance of quantifying sediment budgets of headwater wetlands. The study demonstrated the complex nature of the wetland hydro geomorphology and that certain questions about wetlands require direct field monitoring to be better understood. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text: