Links between valley confinement, landforms and vegetation distribution in a semi-arid valley floor environment, Baviaanskloof, South Africa
- Authors: Smith-Adao, Lindie B
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/953 , vital:20006
- Description: Although a large body of international literature has advanced our understanding of river systems, a considerable amount of gaps exit in the knowledge of dryland systems. River systems reflect complex interactions between biophysical processes and patterns. Understanding how processes generate observed patterns and, in turn, how patterns influence processes is crucial to understanding river structure and function. It requires an interdisciplinary approach in both research and resulting applications. The aim of this thesis was to examine the relationship between valley confinement, fluvial style, valley floor morphology and vegetation in the semi-arid environment of the Baviaanskloof river catchment, South Africa. This interdisciplinary investigation used a mixed method approach that involved desktop analyses and field surveys to understand dynamics at multiple scales, from the whole catchment to local (site, reach and quadrat or sample plot) scales. The desktop analyses included historical rainfall patterns and climate extremes, aerial photograph time-series and remote sensing greenness indices, and the field surveys focussed on cross-valley landform profiles, groundwater depth levels, sediment size distribution and soil chemistry, and vegetation distribution patterns. Based on the integrative assessment of these techniques a framework was developed of the links between valley confinement, surface-groundwater interaction, hydrogeomorphic processes and landforms, vegetation and human activities. Study findings highlighted the fact that very strong links exist between these factors. In this semi-arid area water availability (groundwater and streamflow conditions) was the primary control on valley floor vegetation composition and patterning. One group of species was associated with the wetted channel reaches at confined and semi-confined valley settings, while the other was associated with dry bed channel reaches at unconfined valley settings. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants, in turn, also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi-confined and unconfined valley settings across the valley floor. Valley confinement was a primary control influencing hydrogeomorphic processes and their associated landforms. Alluvial fans and terraces acted as critical additional controls at especially the unconfined valley setting. Implications for restoration efforts in the catchment included strategies that took cognisance of: active revegetation on floodplain surfaces related to former agricultural fields; channel switching associated with the highly dynamic and unpredictable nature of geomorphic features; unstable multi-thread braided channels in the unconfined valley setting; and the selection of representative monitoring sites.
- Full Text:
- Date Issued: 2016
- Authors: Smith-Adao, Lindie B
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/953 , vital:20006
- Description: Although a large body of international literature has advanced our understanding of river systems, a considerable amount of gaps exit in the knowledge of dryland systems. River systems reflect complex interactions between biophysical processes and patterns. Understanding how processes generate observed patterns and, in turn, how patterns influence processes is crucial to understanding river structure and function. It requires an interdisciplinary approach in both research and resulting applications. The aim of this thesis was to examine the relationship between valley confinement, fluvial style, valley floor morphology and vegetation in the semi-arid environment of the Baviaanskloof river catchment, South Africa. This interdisciplinary investigation used a mixed method approach that involved desktop analyses and field surveys to understand dynamics at multiple scales, from the whole catchment to local (site, reach and quadrat or sample plot) scales. The desktop analyses included historical rainfall patterns and climate extremes, aerial photograph time-series and remote sensing greenness indices, and the field surveys focussed on cross-valley landform profiles, groundwater depth levels, sediment size distribution and soil chemistry, and vegetation distribution patterns. Based on the integrative assessment of these techniques a framework was developed of the links between valley confinement, surface-groundwater interaction, hydrogeomorphic processes and landforms, vegetation and human activities. Study findings highlighted the fact that very strong links exist between these factors. In this semi-arid area water availability (groundwater and streamflow conditions) was the primary control on valley floor vegetation composition and patterning. One group of species was associated with the wetted channel reaches at confined and semi-confined valley settings, while the other was associated with dry bed channel reaches at unconfined valley settings. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants, in turn, also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi-confined and unconfined valley settings across the valley floor. Valley confinement was a primary control influencing hydrogeomorphic processes and their associated landforms. Alluvial fans and terraces acted as critical additional controls at especially the unconfined valley setting. Implications for restoration efforts in the catchment included strategies that took cognisance of: active revegetation on floodplain surfaces related to former agricultural fields; channel switching associated with the highly dynamic and unpredictable nature of geomorphic features; unstable multi-thread braided channels in the unconfined valley setting; and the selection of representative monitoring sites.
- Full Text:
- Date Issued: 2016
Modelling the relationship between flow and water quality in South African rivers
- Authors: Slaughter, Andrew Robert
- Date: 2011
- Subjects: Water quality -- Measurement -- South Africa Water quality -- Mathematical models -- South Africa Streamflow -- South Africa Stream measurements -- Mathematical models -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6039 , http://hdl.handle.net/10962/d1006196
- Description: The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.
- Full Text:
- Date Issued: 2011
- Authors: Slaughter, Andrew Robert
- Date: 2011
- Subjects: Water quality -- Measurement -- South Africa Water quality -- Mathematical models -- South Africa Streamflow -- South Africa Stream measurements -- Mathematical models -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6039 , http://hdl.handle.net/10962/d1006196
- Description: The National Water Act (Act 36 of 1998) provides for an ecological Reserve as the quantity (flow) and quality of water needed to protect aquatic ecosystems. While there are methods available to quantify the ecological Reserve in terms of flow, methods of linking flow to water quality are lacking. Therefore, the research presented in this thesis investigated various modelling techniques to estimate the effect of flow on water quality. The aims of the research presented in this thesis were: Aim 1: Can the relationship between flow and water quality be accurately represented by simple statistical models? Aim 2: Can relatively simple models accurately represent the relationship between flow and water quality? Aim 3: Can the effect of diffuse sources be omitted from a water quality model and still obtain realistic simulations, and if so under what conditions? Aim 4: Can models that solely use historical monitoring data, accurately represent the relationships between flow and water quality? In Chapter 3, simple Q-C regressions of flow and water quality were investigated using Department of Water Affairs (DWA) historical monitoring data. It was found that while flow versus salinity regressions gave good regression fits in many cases, the Q-C regression approach is limited. A mechanistic/statistical model that attempted to estimate the point and diffuse signatures of nutrients in response to flow was developed in Chapter 4 using DWA historical monitoring data. The model was verified as accurate in certain case studies using observed point loading information. In Chapter 5, statistical models that link land cover information to diffuse nutrient signatures in response to flow using DWA historical data were developed. While the model estimations are uncertain due to a lack of data, they do provide an estimation of the diffuse signature within catchments where there is flow and land cover information available. Chapter 6 investigates the extension of an existing mass-balance salinity model to estimate the effect of saline irrigation return flow on in-stream salinity. The model gave accurate salinity estimates for a low order stream with little or no irrigation within its catchment, and for a permanently flowing river within a catchment used extensively for irrigation. Chapter 7 investigated a modelling method to estimate the reaction coefficients involved in nitrification using only DWA historical monitoring data. Here, the model used flow information to estimate the residence time of nutrients within the studied river reaches. While the model obtained good estimations of nitrification for the data it was applied to, very few DWA data sets were suitable for the model. Chapter 8 investigated the ability of the in-stream model QUAL2K to estimate nutrient concentrations downstream of point and diffuse inputs of nutrients. It was found that the QUAL2K model can give accurate results in cases where point sources dominate the total nutrient inputs into a river. However, the QUAL2K simulations are too uncertain in cases where there are large diffuse source inputs of nutrients as the load of the diffuse inputs is difficult to measure in the field. This research highlights the problem of data scarcity in terms of temporal resolution as well as the range of constituents measured within DWA historical monitoring data for water quality. This thesis in addition argues that the approach of applying a number of models is preferable to applying one model to investigate the research aims, as particular models would be suited to particular circumstances, and the development of new models allowed the research aims of this thesis to be explored more thoroughly. It is also argued that simpler models that simulate a few key processes that explain the variation in observed data, are more suitable for implementing Integrated Water Resource Management (IWRM) than large comprehensive water quality models. From this research, it is clear that simple statistical models are not adequate for modelling the relationship between flow and water quality, however, relatively simple mechanistic models that simulate a limited number of processes and water quality variables, can provide accurate representations of this relationship. Under conditions where diffuse sources are not a major factor within a catchment, models that omit diffuse sources can obtain realistic simulations of the relationship between flow and water quality. Most of the models investigated in this thesis demonstrate that accurate simulations of the relationships between flow and water quality can be obtained using solely historical monitoring data.
- Full Text:
- Date Issued: 2011
Developing self-regulated learning through the use of meta-cognitive strategies in adventure-based activities
- Authors: Galbraith, Ian William
- Date: 2006
- Subjects: Lilyfontein School Adventure education Education -- South Africa -- Curricula Competency-based education -- South Africa Educational psychology Cognitive learning
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1495 , http://hdl.handle.net/10962/d1003376
- Description: This research investigates the benefits of adventure-based activities used as a learning experience at school level. In order to scientifically investigate these benefits the study is located at a school where an adventure-based programme is being developed as part of the school's curriculum. This programme consists of a range of adventure type experiences including, rock climbing, abseiling, canoeing, mountain biking, group dynamic activities, survival camps, ropes courses and adventure racing. At Lilyfontein School these activities form part of the Life Orientation and life Skill programmes from grade 1 to grade 11. Specialized and qualified staff are used to conduct some of these programmes. Adventure-based activities are rigorous and contain elements of risk which require problem solving, good decision making and sound emotional management. These aspects present both physical and mental challenges to any participant. This study postulates that learners engaged in these adventure type activities are faced with using meta-cognitive strategies to help them through these mental and physical challenges. In doing these activities regularly learners will develop meta-cognitive strategies that will enable them to become better self-regulated learners. A self-regulated learner is able to use meta-cognitive strategies like problem solving, decision making, selfevaluation, self-monitoring, self-reflective thinking or emotional control in life generally. The aim of this research is to conduct an on-going action research study of the adventure-based programmes to determine their worth for the learners at Lilyfontein School and consequently the future of such experiences in a school's curriculum. This forms the primary goal of this research. The secondary goal is to gather valid and reliable evidence required to make an argument for the School's Governing Body (SGB) and Curriculum Development Committee (CDC) to be able to substantiate decisions relating to any such future programmes. This research regards the school context as the activity system which forms a primary case study. In order to extract maximum information from this educational system, embedded case studies will be conducted and monitored. These embedded case studies will be made up of the following groups of people: firstly the learners engaged in a variety of adventure-based experiences, secondly the educators as they observe and perceive the consequences of these experiences, and thirdly the parents as they identifY possible influences of adventure-based experiences on the behaviours, beliefs or habits of their children. In this research study data collecting techniques are used to extract infonnation from the embedded cases. Infonnation is elicited from parents and educators through the use of questionnaires and interviews. For learners, narratives and interviews are used to get a more qualitative sense of their beliefs and feelings on adventure-based experiences. However, in order to capture and document the learners' use of metacognitive strategies as they engage in the rigours of an adventure-based activity a more empirical approach is used. This approach uses in-depth observation, recording and measuring of the learners in action. Video footage is used to record the learners' reactions as they battle with fear, mental-strength, fatigue and decision making to accomplish their goal during an adventure activity. This study claims that an adventure-based experience helps to mediate the learning that will develop selfregulatory strategies in a learner. The limited research in the adventure-based learning field and more significantly the lack of empirical evidence of how meta-cognitive strategies fonn a crucial component of adventure-based activities has meant that the researcher has developed his own recording, measuring and analytical tools to serve this end. He has chosen to use Engestrom's third generation Activity Theory model which provides a useful underlying theory as well as an analytical and interpretive framework for this study. The research was conducted over a period of three years. Findings are considered in relation to the National Curriculum Statement for the GET and FET bands to ensure its relevance in the school context to the National Department of Education's expectations for the Life Orientation curriculum. The empirical findings of this study at Lilyfontein School and their relevance to the curriculum content of the National Curriculum Statement ought to provide convincing data for very important curriculum policy decisions at Lilyfontein School and in the broader educational context.
- Full Text:
- Date Issued: 2006
- Authors: Galbraith, Ian William
- Date: 2006
- Subjects: Lilyfontein School Adventure education Education -- South Africa -- Curricula Competency-based education -- South Africa Educational psychology Cognitive learning
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1495 , http://hdl.handle.net/10962/d1003376
- Description: This research investigates the benefits of adventure-based activities used as a learning experience at school level. In order to scientifically investigate these benefits the study is located at a school where an adventure-based programme is being developed as part of the school's curriculum. This programme consists of a range of adventure type experiences including, rock climbing, abseiling, canoeing, mountain biking, group dynamic activities, survival camps, ropes courses and adventure racing. At Lilyfontein School these activities form part of the Life Orientation and life Skill programmes from grade 1 to grade 11. Specialized and qualified staff are used to conduct some of these programmes. Adventure-based activities are rigorous and contain elements of risk which require problem solving, good decision making and sound emotional management. These aspects present both physical and mental challenges to any participant. This study postulates that learners engaged in these adventure type activities are faced with using meta-cognitive strategies to help them through these mental and physical challenges. In doing these activities regularly learners will develop meta-cognitive strategies that will enable them to become better self-regulated learners. A self-regulated learner is able to use meta-cognitive strategies like problem solving, decision making, selfevaluation, self-monitoring, self-reflective thinking or emotional control in life generally. The aim of this research is to conduct an on-going action research study of the adventure-based programmes to determine their worth for the learners at Lilyfontein School and consequently the future of such experiences in a school's curriculum. This forms the primary goal of this research. The secondary goal is to gather valid and reliable evidence required to make an argument for the School's Governing Body (SGB) and Curriculum Development Committee (CDC) to be able to substantiate decisions relating to any such future programmes. This research regards the school context as the activity system which forms a primary case study. In order to extract maximum information from this educational system, embedded case studies will be conducted and monitored. These embedded case studies will be made up of the following groups of people: firstly the learners engaged in a variety of adventure-based experiences, secondly the educators as they observe and perceive the consequences of these experiences, and thirdly the parents as they identifY possible influences of adventure-based experiences on the behaviours, beliefs or habits of their children. In this research study data collecting techniques are used to extract infonnation from the embedded cases. Infonnation is elicited from parents and educators through the use of questionnaires and interviews. For learners, narratives and interviews are used to get a more qualitative sense of their beliefs and feelings on adventure-based experiences. However, in order to capture and document the learners' use of metacognitive strategies as they engage in the rigours of an adventure-based activity a more empirical approach is used. This approach uses in-depth observation, recording and measuring of the learners in action. Video footage is used to record the learners' reactions as they battle with fear, mental-strength, fatigue and decision making to accomplish their goal during an adventure activity. This study claims that an adventure-based experience helps to mediate the learning that will develop selfregulatory strategies in a learner. The limited research in the adventure-based learning field and more significantly the lack of empirical evidence of how meta-cognitive strategies fonn a crucial component of adventure-based activities has meant that the researcher has developed his own recording, measuring and analytical tools to serve this end. He has chosen to use Engestrom's third generation Activity Theory model which provides a useful underlying theory as well as an analytical and interpretive framework for this study. The research was conducted over a period of three years. Findings are considered in relation to the National Curriculum Statement for the GET and FET bands to ensure its relevance in the school context to the National Department of Education's expectations for the Life Orientation curriculum. The empirical findings of this study at Lilyfontein School and their relevance to the curriculum content of the National Curriculum Statement ought to provide convincing data for very important curriculum policy decisions at Lilyfontein School and in the broader educational context.
- Full Text:
- Date Issued: 2006
A comparative study of L1 and EFL reading abilities amongst junior primary students using different reading schemes in black schools
- Authors: Duncan, Kenneth Foster
- Date: 1995
- Subjects: Black people -- Education (Primary) -- South Africa , English language -- Study and teaching (Primary) -- Foreign speakers -- South Africa , Native language and education , Reading (Primary) -- South Africa , Molteno Project
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2346 , http://hdl.handle.net/10962/d1002628 , Black people -- Education (Primary) -- South Africa , English language -- Study and teaching (Primary) -- Foreign speakers -- South Africa , Native language and education , Reading (Primary) -- South Africa , Molteno Project
- Description: This thesis examines the development of children's reading skills, in both the mother tongue and English as a foreign language, during their first four years of school. It is an attempt to enter the reading world of very young learners in underdeveloped, mainly rural communities in search of practical insights into the teaching of reading in the junior primary classroom. The research focuses specifically on two approaches to reading instruction. The first is the approach traditionally used in black South African schools, characterised by teacher-centredness and rote-recall techniques. The second is a more progressive and communicative approach encapsulated in the language courses of the Molteno Project. Both approaches, and their theoretical underpinnings, are described in some detail. The context of language-in-education policy in South Africa is also reviewed. The research then tests the hypothesis that a communicative approach to reading pedagogy produces measurably better results in pupils than more traditional methods. The research explores the use of quantitative methods of evaluation, giving justification for their use, and examines the practicability of standardised EFL tests at junior primary level. Existing tests are evaluated and found wanting. The process of developing and administering original hybrid-communicative tests is described. The results of these, which were administered over four years to a total of some 6 000 pupils across the first four years of school, are assessed. Implications for testers, teachers, educational administrators and educational NGOs are extrapolated.
- Full Text:
- Date Issued: 1995
- Authors: Duncan, Kenneth Foster
- Date: 1995
- Subjects: Black people -- Education (Primary) -- South Africa , English language -- Study and teaching (Primary) -- Foreign speakers -- South Africa , Native language and education , Reading (Primary) -- South Africa , Molteno Project
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2346 , http://hdl.handle.net/10962/d1002628 , Black people -- Education (Primary) -- South Africa , English language -- Study and teaching (Primary) -- Foreign speakers -- South Africa , Native language and education , Reading (Primary) -- South Africa , Molteno Project
- Description: This thesis examines the development of children's reading skills, in both the mother tongue and English as a foreign language, during their first four years of school. It is an attempt to enter the reading world of very young learners in underdeveloped, mainly rural communities in search of practical insights into the teaching of reading in the junior primary classroom. The research focuses specifically on two approaches to reading instruction. The first is the approach traditionally used in black South African schools, characterised by teacher-centredness and rote-recall techniques. The second is a more progressive and communicative approach encapsulated in the language courses of the Molteno Project. Both approaches, and their theoretical underpinnings, are described in some detail. The context of language-in-education policy in South Africa is also reviewed. The research then tests the hypothesis that a communicative approach to reading pedagogy produces measurably better results in pupils than more traditional methods. The research explores the use of quantitative methods of evaluation, giving justification for their use, and examines the practicability of standardised EFL tests at junior primary level. Existing tests are evaluated and found wanting. The process of developing and administering original hybrid-communicative tests is described. The results of these, which were administered over four years to a total of some 6 000 pupils across the first four years of school, are assessed. Implications for testers, teachers, educational administrators and educational NGOs are extrapolated.
- Full Text:
- Date Issued: 1995
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