A comprehensive approach to scalability assessment of ICTD projects : a case study of ICT4RED
- Authors: Baduza, Gugulethu Qhawekazi
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178435 , vital:42939
- Description: Access restricted until April 2023. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2021
- Full Text:
- Authors: Baduza, Gugulethu Qhawekazi
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178435 , vital:42939
- Description: Access restricted until April 2023. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2021
- Full Text:
Constraining simulation uncertainties in a hydrological model of the Congo River Basin including a combined modelling approach for channel-wetland exchanges
- Authors: Kabuya, Pierre Mulamba
- Date: 2021-04
- Subjects: Congo River Watershed , Watersheds -- Congo (Democratic Republic) , Hydrologic models , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Wetland hydrology
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177997 , vital:42897 , 10.21504/10962/177997
- Description: Compared to other large river basins of the world, such as the Amazon, the Congo River Basin appears to be the most ungauged and less studied. This is partly because the basin lacks sufficient observational hydro-climatic monitoring stations and appropriate information on physiographic basin properties at a spatial scale deemed for hydrological applications, making it difficult to estimate water resources at the scale of sub-basins (Chapter 3). In the same time, the basin is facing the challenges related to rapid population growth, uncontrolled urbanisation as well as climate change. Adequate quantification of hydrological processes across different spatial and temporal scales in the basin, and the drivers of change, is essential for prediction and strategic planning to ensure sustainable management of water resources in the Congo River Basin. Hydrological models are particularly important to generate the required information. However, the shortness of the available streamflow records, lack of spatial representativeness of the available streamflow gauging stations and the lack of understanding of the processes in channel-wetland exchanges, are the main challenges that constrain the use of traditional approaches to models development. They also contribute to increased uncertainty in the estimation of water resources across the basin (Chapter 1 and 2). Given this ungauged nature of the Congo River Basin, it is important to resort to hydrological modelling approaches that can reasonably quantify and model the uncertainty associated with water resources estimation (Chapter 4) to make hydrological predictions reliable. This study explores appropriate methods for hydrological predictions and water resources assessment in ungauged catchments of the Congo River Basin. In this context, the core modelling framework combines the quantification of uncertainty in constraint indices, hydrological modelling and hydrodynamic modelling. The latter accounts for channel-wetland exchanges in sub-basins where wetlands exert considerable influence on downstream flow regimes at the monthly time scale. The constraint indices are the characteristics of a sub-basin’s long-term hydrological behaviour and may reflect the dynamics of the different components of the catchment water balance such as climate, water storage and different runoff processes. Currently, six constraint indices namely the mean monthly runoff volume (MMQ in m3 *106), mean monthly groundwater recharge depth (MMR in mm), the 10th, 50th and 90th percentiles of the flow duration curve expressed as a fraction of MMQ (Q10/MMQ, Q50/MMQ, Q90/MMQ) and the percentage of time that zero flows are expected (%Zero), are used in the modelling approach. These were judged to be the minimum number of key indices that can discriminate between different hydrological responses. The constraint indices in the framework help to determine an uncertainty range within which behavioural model parameters of the expected hydrological response can be identified. Predictive equations of the constraint indices across all climate and physiographic regions of the Congo Basin were based only on the aridity index because it was the most influential sub-basin attribute (Chapter 5) for which quantitative information was available. The degree of uncertainty in the constraint Q10/MMQ and Q50/MMQ indices is less than 41%, while it is somewhat higher for the mean monthly runoff (MMQ) and Q90/MMQ constraint indices. The established uncertainty ranges of the constraint indices were tested in some selected sub-basins of the Congo Basin, including the Lualaba (93 sub-basins), Sangha (24 sub-basins), Oubangui (19 sub-basins), Batéké plateaux (4 sub-basins), Kasai (4 sub-basins) and Inkisi (3 sub-basins). The results proved useful through the application of a 2-stage uncertainty approach of the PITMAN model. However, it comes out of this study that the application of the original constraint indices ranges (Chapter 5) generated satisfactory simulation results in some areas, while in others both small and large adjustments were required to fully capture some aspects of the observed hydrological responses (Chapter 6). Part of the reason is attributed to the availability and quality of streamflow data used to develop the constraint indices ranges (Chapter 5). The main issue identified in the modelling process was whether the changes made to the original constraints at headwater-gauged sub-basins can be applied to ungauged upstream sub-basins to match the observed flow at downstream gauging stations. Ideally, only gauged sub-basin’s constraints can be easily revised based on the observed flow. However, the refinement made to gauged sub-basins alone may fail to substantially affect the results if ungauged upstream sub-basins exert a major impact on defining downstream hydrological response. The majority of gauging stations used in this analysis are located downstream of many upstream ungauged sub-basins and therefore adjustments were required in ungauged sub-basins. These adjustments consist of shifting the full range of a constraint index either towards higher or lower values, depending on the degree to which the simulated uncertainty bounds depart from the observed flow. While this modelling approach seems effective in capturing many aspects of the hydrological responses with a reduced level of uncertainty compared to a previous study, it is recommended that the approach be extended to the remaining parts of the Congo Basin and assessed under current and future development conditions including environmental changes. A 2D hydrodynamic river-wetland model (LISFLOOD-FP) has been used to explicitly represent the inundation process exchanges between river channels and wetland systems. The hydrodynamic modelling outputs are used to calibrate the PITMAN wetland sub-model parameters. The five hydrodynamic models constructed for Ankoro, Kamalondo, Kundelungu, Mweru and Tshiangalele wetland systems have been partially validated using independent estimates of inundation extents available from Landsat imagery. Other sources of data such as remote sensing of water level altimetry, SAR images and wetland storage estimates may be used to improve the validation results. However, the important objective in this study was to make sure that flow volume exchanges between river channels and their adjacent floodplains were being simulated realistically. The wetland sub-model parameters are calibrated in a spreadsheet version of the PITMAN wetland routine to achieve visual correspondence between the LISFLOOD-FP and PITMAN wetland sub-model outputs (Storage volumes and channel outputs). The hysteretic patterns of the river-wetland processes were quantified using hysteresis indices and were associated with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. One example is the scale parameter of the return flow function (AA), which shows a good relationship with the average surface slope of the wetland when the coefficient parameter (BB) of the same function is kept constant to a value of 1.25. The same parameter (AA) is a good indicator of the wetland emptying mechanism. A small AA indicates a wetland that slowly releases its flow, resulting in a highly delayed and attenuated hydrological response in downstream sub-basins. This understanding has a practical advantage for the estimation of the PITMAN wetland parameters in the many areas where it is not possible, or where the resources are not available, to run complex hydrodynamic models (Chapter 7). The inclusion of these LISFLOOD-FP informed wetland parameters in the basin-scale hydrological modelling results in acceptable simulations for the lower Lualaba drainage system. The small wetlands, like Ankoro and Tshiangalele, have a negligible impact on downstream flow regimes, whereas large wetlands, such as Kamalondo and Mweru, have very large impacts. In general, the testing of the original constraint indices in the region of wetlands and further downstream of the Lualaba drainage system has shown acceptable results. However, there remains an unresolved uncertainty issue related to the under and over-estimation of some aspects of the hydrological response at both Mulongo and Ankoro, two gauging stations in the immediate downstream of the Kamalondo wetland system. It is difficult to attribute this uncertainty to Kamalondo wetland parameters alone because many of the incremental sub-basins contributing to wetland inflows are ungauged. The issue at Mulongo is the under simulation of low flow, while the high flows at the Ankoro gauging station are over-simulated. However, the pattern of the calibrated constraint indices in this region (Chapter 8) shows that the under simulation of low flow at Mulongo cannot be attributed to incremental sub-basins (between Bukama, Kapolowe and Mulongo gauging stations), because their Q90/MMQ constraint indices are even slightly above the original constraint ranges, but maintain a spatial consistency with sub-basins of other regions. Similarly, sub-basins located between Mulongo, Luvua and Ankoro gauging stations have high flow indices slightly below the original constraint ranges and therefore they are unlikely to be responsible for the over simulation of high flow at the Ankoro gauging station. These facts highlight the need for a further understanding of the complex wetland system of Kamalondo. Short-term data collection and monitoring programme are required. Important tributaries that drain to this wetland need to be monitored by installing water level loggers and periodically collecting flow data and river bathymetry. This programme should lead to the development of rating curves of wetland input tributaries. This would partially solve the unresolved uncertainty issues at the Ankoro and Mulongo gauging stations. The integrated modelling approach offers many opportunities in the Congo Basin. The quantified and modelled uncertainty helps to identify regions with high uncertainty and allows for the identification of various data collection and management strategies that can potentially contribute to the uncertainty reduction. The quantified channel-wetland exchanges contribute to the improvement of the overall knowledge of water resources estimation within the regions where the effects of wetlands are evident even at the monthly time scale. In contrast, ignoring uncertainty in the estimates of water resources availability means that water resources planning and management decisions in the Congo Basin will continue to be based on inadequate information and unquantified uncertainty, thus increasing the risk associated with water resources decision making. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Authors: Kabuya, Pierre Mulamba
- Date: 2021-04
- Subjects: Congo River Watershed , Watersheds -- Congo (Democratic Republic) , Hydrologic models , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Wetland hydrology
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177997 , vital:42897 , 10.21504/10962/177997
- Description: Compared to other large river basins of the world, such as the Amazon, the Congo River Basin appears to be the most ungauged and less studied. This is partly because the basin lacks sufficient observational hydro-climatic monitoring stations and appropriate information on physiographic basin properties at a spatial scale deemed for hydrological applications, making it difficult to estimate water resources at the scale of sub-basins (Chapter 3). In the same time, the basin is facing the challenges related to rapid population growth, uncontrolled urbanisation as well as climate change. Adequate quantification of hydrological processes across different spatial and temporal scales in the basin, and the drivers of change, is essential for prediction and strategic planning to ensure sustainable management of water resources in the Congo River Basin. Hydrological models are particularly important to generate the required information. However, the shortness of the available streamflow records, lack of spatial representativeness of the available streamflow gauging stations and the lack of understanding of the processes in channel-wetland exchanges, are the main challenges that constrain the use of traditional approaches to models development. They also contribute to increased uncertainty in the estimation of water resources across the basin (Chapter 1 and 2). Given this ungauged nature of the Congo River Basin, it is important to resort to hydrological modelling approaches that can reasonably quantify and model the uncertainty associated with water resources estimation (Chapter 4) to make hydrological predictions reliable. This study explores appropriate methods for hydrological predictions and water resources assessment in ungauged catchments of the Congo River Basin. In this context, the core modelling framework combines the quantification of uncertainty in constraint indices, hydrological modelling and hydrodynamic modelling. The latter accounts for channel-wetland exchanges in sub-basins where wetlands exert considerable influence on downstream flow regimes at the monthly time scale. The constraint indices are the characteristics of a sub-basin’s long-term hydrological behaviour and may reflect the dynamics of the different components of the catchment water balance such as climate, water storage and different runoff processes. Currently, six constraint indices namely the mean monthly runoff volume (MMQ in m3 *106), mean monthly groundwater recharge depth (MMR in mm), the 10th, 50th and 90th percentiles of the flow duration curve expressed as a fraction of MMQ (Q10/MMQ, Q50/MMQ, Q90/MMQ) and the percentage of time that zero flows are expected (%Zero), are used in the modelling approach. These were judged to be the minimum number of key indices that can discriminate between different hydrological responses. The constraint indices in the framework help to determine an uncertainty range within which behavioural model parameters of the expected hydrological response can be identified. Predictive equations of the constraint indices across all climate and physiographic regions of the Congo Basin were based only on the aridity index because it was the most influential sub-basin attribute (Chapter 5) for which quantitative information was available. The degree of uncertainty in the constraint Q10/MMQ and Q50/MMQ indices is less than 41%, while it is somewhat higher for the mean monthly runoff (MMQ) and Q90/MMQ constraint indices. The established uncertainty ranges of the constraint indices were tested in some selected sub-basins of the Congo Basin, including the Lualaba (93 sub-basins), Sangha (24 sub-basins), Oubangui (19 sub-basins), Batéké plateaux (4 sub-basins), Kasai (4 sub-basins) and Inkisi (3 sub-basins). The results proved useful through the application of a 2-stage uncertainty approach of the PITMAN model. However, it comes out of this study that the application of the original constraint indices ranges (Chapter 5) generated satisfactory simulation results in some areas, while in others both small and large adjustments were required to fully capture some aspects of the observed hydrological responses (Chapter 6). Part of the reason is attributed to the availability and quality of streamflow data used to develop the constraint indices ranges (Chapter 5). The main issue identified in the modelling process was whether the changes made to the original constraints at headwater-gauged sub-basins can be applied to ungauged upstream sub-basins to match the observed flow at downstream gauging stations. Ideally, only gauged sub-basin’s constraints can be easily revised based on the observed flow. However, the refinement made to gauged sub-basins alone may fail to substantially affect the results if ungauged upstream sub-basins exert a major impact on defining downstream hydrological response. The majority of gauging stations used in this analysis are located downstream of many upstream ungauged sub-basins and therefore adjustments were required in ungauged sub-basins. These adjustments consist of shifting the full range of a constraint index either towards higher or lower values, depending on the degree to which the simulated uncertainty bounds depart from the observed flow. While this modelling approach seems effective in capturing many aspects of the hydrological responses with a reduced level of uncertainty compared to a previous study, it is recommended that the approach be extended to the remaining parts of the Congo Basin and assessed under current and future development conditions including environmental changes. A 2D hydrodynamic river-wetland model (LISFLOOD-FP) has been used to explicitly represent the inundation process exchanges between river channels and wetland systems. The hydrodynamic modelling outputs are used to calibrate the PITMAN wetland sub-model parameters. The five hydrodynamic models constructed for Ankoro, Kamalondo, Kundelungu, Mweru and Tshiangalele wetland systems have been partially validated using independent estimates of inundation extents available from Landsat imagery. Other sources of data such as remote sensing of water level altimetry, SAR images and wetland storage estimates may be used to improve the validation results. However, the important objective in this study was to make sure that flow volume exchanges between river channels and their adjacent floodplains were being simulated realistically. The wetland sub-model parameters are calibrated in a spreadsheet version of the PITMAN wetland routine to achieve visual correspondence between the LISFLOOD-FP and PITMAN wetland sub-model outputs (Storage volumes and channel outputs). The hysteretic patterns of the river-wetland processes were quantified using hysteresis indices and were associated with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. One example is the scale parameter of the return flow function (AA), which shows a good relationship with the average surface slope of the wetland when the coefficient parameter (BB) of the same function is kept constant to a value of 1.25. The same parameter (AA) is a good indicator of the wetland emptying mechanism. A small AA indicates a wetland that slowly releases its flow, resulting in a highly delayed and attenuated hydrological response in downstream sub-basins. This understanding has a practical advantage for the estimation of the PITMAN wetland parameters in the many areas where it is not possible, or where the resources are not available, to run complex hydrodynamic models (Chapter 7). The inclusion of these LISFLOOD-FP informed wetland parameters in the basin-scale hydrological modelling results in acceptable simulations for the lower Lualaba drainage system. The small wetlands, like Ankoro and Tshiangalele, have a negligible impact on downstream flow regimes, whereas large wetlands, such as Kamalondo and Mweru, have very large impacts. In general, the testing of the original constraint indices in the region of wetlands and further downstream of the Lualaba drainage system has shown acceptable results. However, there remains an unresolved uncertainty issue related to the under and over-estimation of some aspects of the hydrological response at both Mulongo and Ankoro, two gauging stations in the immediate downstream of the Kamalondo wetland system. It is difficult to attribute this uncertainty to Kamalondo wetland parameters alone because many of the incremental sub-basins contributing to wetland inflows are ungauged. The issue at Mulongo is the under simulation of low flow, while the high flows at the Ankoro gauging station are over-simulated. However, the pattern of the calibrated constraint indices in this region (Chapter 8) shows that the under simulation of low flow at Mulongo cannot be attributed to incremental sub-basins (between Bukama, Kapolowe and Mulongo gauging stations), because their Q90/MMQ constraint indices are even slightly above the original constraint ranges, but maintain a spatial consistency with sub-basins of other regions. Similarly, sub-basins located between Mulongo, Luvua and Ankoro gauging stations have high flow indices slightly below the original constraint ranges and therefore they are unlikely to be responsible for the over simulation of high flow at the Ankoro gauging station. These facts highlight the need for a further understanding of the complex wetland system of Kamalondo. Short-term data collection and monitoring programme are required. Important tributaries that drain to this wetland need to be monitored by installing water level loggers and periodically collecting flow data and river bathymetry. This programme should lead to the development of rating curves of wetland input tributaries. This would partially solve the unresolved uncertainty issues at the Ankoro and Mulongo gauging stations. The integrated modelling approach offers many opportunities in the Congo Basin. The quantified and modelled uncertainty helps to identify regions with high uncertainty and allows for the identification of various data collection and management strategies that can potentially contribute to the uncertainty reduction. The quantified channel-wetland exchanges contribute to the improvement of the overall knowledge of water resources estimation within the regions where the effects of wetlands are evident even at the monthly time scale. In contrast, ignoring uncertainty in the estimates of water resources availability means that water resources planning and management decisions in the Congo Basin will continue to be based on inadequate information and unquantified uncertainty, thus increasing the risk associated with water resources decision making. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
Indigenous knowledge of ecosystem services in rural communities of the Eastern Cape, South Africa
- Authors: Murata, Chenai
- Date: 2021-04
- Subjects: Ethnoscience -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Nature -- Effect of human beings on -- South Africa -- Eastern Cape , Human ecology -- South Africa -- Eastern Cape , Human beings -- Effect of environment on -- South Africa -- Eastern Cape , South Africa -- Eastern Cape -- Rural conditions
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177929 , vital:42891 , 10.21504/10962/177929
- Description: This thesis is on indigenous knowledge of ecosystem services. The ecosystem service framework and its associated concepts are fairly young, having been introduced in the ecological discipline in the 1980s. The ecosystem service framework posits that the wellbeing of humans and their communities is dependent on services supplied by ecosystems. It emphasises that for the ecosystems to be able to supply the services, they need to be in a well-functioning state. This idea of well-functioning is predicated on the argument that the ecosystem service framework enjoins resource users to exercise responsible stewardship to prevent degradation and overharvesting. Moreover, the concept of dependence suggests that ecosystem services are of value to humans. The dominant means of measuring the value of ecosystem services has been the economic valuation method in which the contribution that each service makes to human wellbeing is quantified into monetary units. The framework disaggregates the services into four groups, namely provisioning, cultural, supporting and regulatory and seeks to all the pillars of human wellbeing including health, subsistence and spirituality into each of these groups. In doing all this, the framework significantly reconfigures the way we look at and present human-nature relations. This change has the potential to influence significant shifts in how ecological research and intervention programmes are conducted in the foreseeable future. However, the reality that the ecosystem service framework was formulated within, and is informed by the scientific epistemology begs the question: what do traditional rural communities who depend mainly on indigenous knowledge systems (IKS) for shaping and interoperating their relations with nature know of the ecosystem service concept? Rural communities are the ones who interact directly with nature on a day-to-day basis. This makes them a very critical component in the ecosystem service framework. Although South Africa has had studies in the ecosystem service theme, little has been done to attempt to investigate and document indigenous knowledge of ecosystem services that rural communities possess. By focusing only on scientific knowledge of ecosystem services, the South African literature does not do justice to the plural epistemologies of the ecosystem service users in the country. More importantly, the continued dearth of public information on indigenous knowledge of ecosystem services can potentially obstruct implementation of locally sensitive intervention programmes because nothing is known about how the local communities conceptualise the ecosystem service framework. All this presents a crucial gap in the South African research; one that unless effort is made to contribute towards filling it, our knowledge of how communities experience the ecosystem service framework in South Africa will remain skewed. This study set out to investigate and document indigenous knowledge of ecosystem services in order to contribute towards filling this gap. Indigenous knowledge system is an umbrella epistemic system that includes lay ecological knowledge (LEK), traditional ecological knowledge (TEK) and many other related organized systems of knowing. Although the thesis has a chapter on LEK, its primary focus was TEK because the thesis was interested in unravelling how aspects of tradition including taboos, customs, traditional rules and belief in ancestral forces influence local communities’ knowledge of some key aspects of the ecosystem service framework including knowledge of various ecosystem services, valuation of ecosystem services, management of ecosystem services and perceptions of the management practices. The decision to focus on TEK was based on the reasoning that rural communities of the Eastern Cape boast a strong reputation of being traditional, recognizing ancestral spirits, legends and taboos as critical tools of knowledge generation and transmission. Using both mixed methods in some chapters and the qualitative approach alone in others, the study collected data in five villages of Mgwalana, Mahlungulu, Colana, Gogela and Nozitshena located in the north eastern part of Eastern Cape Province of South Africa, a region formerly called Transkei. The data were collected not on ecosystem services; but on the local people’s knowledge of ecosystem services. Although literature was consulted, the study regarded respondents as the primary source of data, hence the findings and conclusions presented in this thesis are about what local people know about ecosystem services. The study uses critical realist theoretical lenses to interpret respondents’ reports. The lenses included the principle of the separation between ontology and epistemology, the iceberg metaphor of ontology, epistemological pluralism and the hermeneutic dimension. These lenses were used to make sense of both the knowledge system of local people and the things about which their knowledge was. As part of discussing the local people’s knowledge, the study sometimes refers to science. This is not because I expected them to demonstrate knowledge similar to science. Instead, it was a critical realist dialectical way of explaining what something is by demonstrating what it is not. The study made a couple of key findings that can potentially enhance the growth of the South African ecosystem service discipline. First, respondents demonstrated knowledge of ecosystem services by mentioning a range of them such as drinking water, medicinal plants, cultural plants and fuelwood and how they affect the wellbeing of humans. However, what they did not have good knowledge of is that nature services can be classified into the four groups of supporting, regulatory, cultural and provisioning. Among the four ecosystem services groups, respondents could identify two only; provisional and cultural. Second, local communities depend heavily on ecosystem services for their well-being. The services include fuelwood, construction timber, medicinal plants, wild fruits, wild fish, cultural services and thatch grass. Although they appreciate that ecosystem services have value to their wellbeing, local people found it difficult to represent the value in monetary units. The conditions that make it difficult for local people to perceive ecosystem services as commodities include the absence of well-defined property system, lack of a quantitative consumer tradition and absence of an economic conception of nature. Third, local people understand the need to keep ecosystems in a well-functioning state hence they implement several traditional practices to manage ecosystem services. These practices include taboos, designating certain resources as sacred, legends, customary law, as well as some secular practices including gelesha and stone terracing. However, it is not easy to understand how traditional management practices work because they are not empirically observable. Fourth, local people possess knowledge of the reality that if not well managed, ecosystems can undergo degradation and hence fail to supply the services needed for human wellbeing. However, they explain the causes of degradation in terms of changes observable at the empirical level and the invisible causal power of supernatural forces. The inclusion of natural forces in degradation explanations marks a departure from the scientific explanations that revolve around biophysical processes. Fifth, the use of traditional management practices such as taboos to management ecosystems is under threat at the local communities. The threat can be attributed to three groups of causes, namely changes in worldviews due to adoption of formal education and Christianity, institutional disharmony playing out between the state and local traditional leadership, and lifestyle changes. These challenges constrain the opportunity for local people to apply traditional management practices to prevent the degradation of ecosystems. The net implication of this is that it renders it difficult for researchers and policy makers to assess the effectiveness of traditional management practices because they are not being implemented in full. In light of all these findings, the thesis concludes that TEK is underlabouring for the ecosystem service framework in the sense that it is used by local communities to generate knowledge of ecological concepts and phenomena. This means that TEK does not exist for the sake of its own self. Drawing from this finding, the study proposes a framework of analysing TEK as an underlabourer for social-ecological triggers or issues. Nonetheless, there are few factors that can be sources of limitation to the study. These include the reality that it was difficult to access pure traditional knowledge because over the years the local communities have received many state-sponsored ecological intervention programmes and a possible personal bias given the reality that I grew up in a traditional household and my father was a key holder or TEK. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021 , Thesis chapter to be published in 'Green and Low-Carbon Economy'. Journal available: https://ojs.bonviewpress.com/index.php/GLCE/index
- Full Text:
- Authors: Murata, Chenai
- Date: 2021-04
- Subjects: Ethnoscience -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Nature -- Effect of human beings on -- South Africa -- Eastern Cape , Human ecology -- South Africa -- Eastern Cape , Human beings -- Effect of environment on -- South Africa -- Eastern Cape , South Africa -- Eastern Cape -- Rural conditions
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177929 , vital:42891 , 10.21504/10962/177929
- Description: This thesis is on indigenous knowledge of ecosystem services. The ecosystem service framework and its associated concepts are fairly young, having been introduced in the ecological discipline in the 1980s. The ecosystem service framework posits that the wellbeing of humans and their communities is dependent on services supplied by ecosystems. It emphasises that for the ecosystems to be able to supply the services, they need to be in a well-functioning state. This idea of well-functioning is predicated on the argument that the ecosystem service framework enjoins resource users to exercise responsible stewardship to prevent degradation and overharvesting. Moreover, the concept of dependence suggests that ecosystem services are of value to humans. The dominant means of measuring the value of ecosystem services has been the economic valuation method in which the contribution that each service makes to human wellbeing is quantified into monetary units. The framework disaggregates the services into four groups, namely provisioning, cultural, supporting and regulatory and seeks to all the pillars of human wellbeing including health, subsistence and spirituality into each of these groups. In doing all this, the framework significantly reconfigures the way we look at and present human-nature relations. This change has the potential to influence significant shifts in how ecological research and intervention programmes are conducted in the foreseeable future. However, the reality that the ecosystem service framework was formulated within, and is informed by the scientific epistemology begs the question: what do traditional rural communities who depend mainly on indigenous knowledge systems (IKS) for shaping and interoperating their relations with nature know of the ecosystem service concept? Rural communities are the ones who interact directly with nature on a day-to-day basis. This makes them a very critical component in the ecosystem service framework. Although South Africa has had studies in the ecosystem service theme, little has been done to attempt to investigate and document indigenous knowledge of ecosystem services that rural communities possess. By focusing only on scientific knowledge of ecosystem services, the South African literature does not do justice to the plural epistemologies of the ecosystem service users in the country. More importantly, the continued dearth of public information on indigenous knowledge of ecosystem services can potentially obstruct implementation of locally sensitive intervention programmes because nothing is known about how the local communities conceptualise the ecosystem service framework. All this presents a crucial gap in the South African research; one that unless effort is made to contribute towards filling it, our knowledge of how communities experience the ecosystem service framework in South Africa will remain skewed. This study set out to investigate and document indigenous knowledge of ecosystem services in order to contribute towards filling this gap. Indigenous knowledge system is an umbrella epistemic system that includes lay ecological knowledge (LEK), traditional ecological knowledge (TEK) and many other related organized systems of knowing. Although the thesis has a chapter on LEK, its primary focus was TEK because the thesis was interested in unravelling how aspects of tradition including taboos, customs, traditional rules and belief in ancestral forces influence local communities’ knowledge of some key aspects of the ecosystem service framework including knowledge of various ecosystem services, valuation of ecosystem services, management of ecosystem services and perceptions of the management practices. The decision to focus on TEK was based on the reasoning that rural communities of the Eastern Cape boast a strong reputation of being traditional, recognizing ancestral spirits, legends and taboos as critical tools of knowledge generation and transmission. Using both mixed methods in some chapters and the qualitative approach alone in others, the study collected data in five villages of Mgwalana, Mahlungulu, Colana, Gogela and Nozitshena located in the north eastern part of Eastern Cape Province of South Africa, a region formerly called Transkei. The data were collected not on ecosystem services; but on the local people’s knowledge of ecosystem services. Although literature was consulted, the study regarded respondents as the primary source of data, hence the findings and conclusions presented in this thesis are about what local people know about ecosystem services. The study uses critical realist theoretical lenses to interpret respondents’ reports. The lenses included the principle of the separation between ontology and epistemology, the iceberg metaphor of ontology, epistemological pluralism and the hermeneutic dimension. These lenses were used to make sense of both the knowledge system of local people and the things about which their knowledge was. As part of discussing the local people’s knowledge, the study sometimes refers to science. This is not because I expected them to demonstrate knowledge similar to science. Instead, it was a critical realist dialectical way of explaining what something is by demonstrating what it is not. The study made a couple of key findings that can potentially enhance the growth of the South African ecosystem service discipline. First, respondents demonstrated knowledge of ecosystem services by mentioning a range of them such as drinking water, medicinal plants, cultural plants and fuelwood and how they affect the wellbeing of humans. However, what they did not have good knowledge of is that nature services can be classified into the four groups of supporting, regulatory, cultural and provisioning. Among the four ecosystem services groups, respondents could identify two only; provisional and cultural. Second, local communities depend heavily on ecosystem services for their well-being. The services include fuelwood, construction timber, medicinal plants, wild fruits, wild fish, cultural services and thatch grass. Although they appreciate that ecosystem services have value to their wellbeing, local people found it difficult to represent the value in monetary units. The conditions that make it difficult for local people to perceive ecosystem services as commodities include the absence of well-defined property system, lack of a quantitative consumer tradition and absence of an economic conception of nature. Third, local people understand the need to keep ecosystems in a well-functioning state hence they implement several traditional practices to manage ecosystem services. These practices include taboos, designating certain resources as sacred, legends, customary law, as well as some secular practices including gelesha and stone terracing. However, it is not easy to understand how traditional management practices work because they are not empirically observable. Fourth, local people possess knowledge of the reality that if not well managed, ecosystems can undergo degradation and hence fail to supply the services needed for human wellbeing. However, they explain the causes of degradation in terms of changes observable at the empirical level and the invisible causal power of supernatural forces. The inclusion of natural forces in degradation explanations marks a departure from the scientific explanations that revolve around biophysical processes. Fifth, the use of traditional management practices such as taboos to management ecosystems is under threat at the local communities. The threat can be attributed to three groups of causes, namely changes in worldviews due to adoption of formal education and Christianity, institutional disharmony playing out between the state and local traditional leadership, and lifestyle changes. These challenges constrain the opportunity for local people to apply traditional management practices to prevent the degradation of ecosystems. The net implication of this is that it renders it difficult for researchers and policy makers to assess the effectiveness of traditional management practices because they are not being implemented in full. In light of all these findings, the thesis concludes that TEK is underlabouring for the ecosystem service framework in the sense that it is used by local communities to generate knowledge of ecological concepts and phenomena. This means that TEK does not exist for the sake of its own self. Drawing from this finding, the study proposes a framework of analysing TEK as an underlabourer for social-ecological triggers or issues. Nonetheless, there are few factors that can be sources of limitation to the study. These include the reality that it was difficult to access pure traditional knowledge because over the years the local communities have received many state-sponsored ecological intervention programmes and a possible personal bias given the reality that I grew up in a traditional household and my father was a key holder or TEK. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021 , Thesis chapter to be published in 'Green and Low-Carbon Economy'. Journal available: https://ojs.bonviewpress.com/index.php/GLCE/index
- Full Text:
The further development, application and evaluation of a sediment yield model (WQSED) for catchment management in African catchments
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
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