Determining the hydrological functioning of the palmiet wetlands in the Eastern and Western Cape South Africa
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- Full Text:
- Date Issued: 2019
Using a social-ecological systems approach to investigate hillslope seep wetlands ecosystem structure and functionality in the Tsitsa River catchment, Eastern Cape, South Africa
- Authors: Libala, Notiswa
- Date: 2019
- Subjects: Wetland management -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland conservation -- South Africa -- Eastern Cape , Slopes (Physical geography) -- South Africa -- Eastern Cape , Vegetation management -- South Africa -- Tsitsa River Catchment , Land degradation -- Control -- South Africa -- Tsitsa River Catchment , Grazing -- Environmental aspects -- South Africa -- Tsitsa River Catchment , Ecosystem management -- South Africa -- Tsitsa River Catchment , Wetland plants -- Effect of grazing on
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115936 , vital:34270
- Description: Wetlands are critical ecosystems that can provide services of great social, economic and environmental value to the society. Yet, in South Africa, hillslope seep wetlands are among the most threatened ecosystems due to human-induced activities and are disappearing rapidly. Further, despite the potential vulnerability of hillslope seep wetland to disturbances, and their criticality in relation to all year round provision of forage for livestock grazing, they are among the most poorly studied wetland systems. Using a social-ecological system framing, and drawing on a range of ecological and social sciences methods, this study shed light on ways in which an integrative approach can contribute to sustainable utilisation of hillslope seep wetlands in the Tsitsa River catchment in the Eastern Cape province of South Africa. The study specific objectives were to i) evaluate the performance of Floristic Quality Assessment Index (FQAI), WET-Health and Floristic Assessment Quotient for Wetlands Index (FQAWet) indices for assessing hillslope seep wetlands ecological health ii) develop a trait-based approach for assessing the potential resilience and vulnerability of hillslope seep wetland plant species to disturbances, iii) assess the role of hillslope seep wetlands in the local communities in relation to livestock, and explore understanding of local people about the value of hillslope seep wetlands, iv) demonstrate collaborative insights emerging from an integrative social-ecological system research process to inform sustainable management of hillslope seep wetlands. A total of 11 hillslope seep wetlands were visually classified based on the level of erosion. Plant species composition within the wetlands was determined along a 100 m line transects across the hillslope wetland sites. 5 quadrats of 0.2m2 were also placed along transect for vegetation collection and cover. The plant species collected were used to calculate (FQAI) and FQAWet scores to evaluate the condition of hillslope seep wetlands. The degree of human disturbances was assessed using the Anthropogenic Activity Index (AAI), an index for qualitatively assessing the degree of human disturbance based on visual inspection of a wetland site. Factors represented in the AAI, include: (i) surrounding land use intensity; (ii) soil disturbance; (iii) hydrological alteration; (iv) habitat alteration within wetland; (v) vegetation community quality. The vegetation samples were collected in summer 2016 and winter 2017. All assessed indices were regressed against AAI to evaluate their performances. All assessed indices FQAI, FQAWet and WET-Health showed that hillslope seep wetland were impacted by human activities. FQAIall and WET-Health showed the strongest response to AAI in winter, while FQAIdom and FAQWet showed a weak response to AAI in all seasons. Overall, the findings of this study suggest that FQAIall and WET-Health are potentially better tools for assessing the biological conditions of hillslope seep wetland in South Africa. A novel trait-based approach was developed using seven plant traits and 27 trait attributes. Based on the developed approach, plant species were grouped into three potentially vulnerable groups in relation to grazing pressure. It was then predicted that species belonging to the highly vulnerable group would be less dominant at the highly disturbed sites, as well as in the winter season when grazing pressure is at its highest. The result corresponds largely with the seasonal predictions; however this was not the case for sites. The approach developed in this study worked and it was useful for predicting the potential responses of plant species in hillslope seep wetlands to grazing pressure. The success of the approach seasonally could be attributed to the careful selection of the traits, reflecting the mechanistic relationship between the grazing mode of stress on vegetation and trait-mediated biotic response. However, this still need to be refined using accurate vegetation cover methods that might have had impact on the lack of correspondence within sites. The results of the present study revealed that communities largely perceive hillslope seep wetlands as important ecosystems for their livelihoods. They recognise that the importance stems from services provided by the wetlands, particularly for livestock grazing during the dry season. Although hillslope seep wetlands are viewed as important ecosystems for livelihoods, the communities also perceive these wetlands as highly eroded ecosystems. Community members indicate willingness to strengthen local natural resource governance systems, which could lead to better management of hillslope seep wetlands. A range of protective strategies for hillslope seep were suggested by community members, including fencing, active herding and rotational grazing. The study suggests that active involvement of local communities is critical to the successful management of natural resources. The study highlights the need to consider the role of local people as influential components within social-ecological systems in order to promote effective management and conservation interventions of hillslope seep wetlands. Overall, the study highlights the criticality of an integrative social-ecological system approach for holistic management of hillslope seep wetlands within the studied catchment.
- Full Text:
- Date Issued: 2019
- Authors: Libala, Notiswa
- Date: 2019
- Subjects: Wetland management -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland conservation -- South Africa -- Eastern Cape , Slopes (Physical geography) -- South Africa -- Eastern Cape , Vegetation management -- South Africa -- Tsitsa River Catchment , Land degradation -- Control -- South Africa -- Tsitsa River Catchment , Grazing -- Environmental aspects -- South Africa -- Tsitsa River Catchment , Ecosystem management -- South Africa -- Tsitsa River Catchment , Wetland plants -- Effect of grazing on
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115936 , vital:34270
- Description: Wetlands are critical ecosystems that can provide services of great social, economic and environmental value to the society. Yet, in South Africa, hillslope seep wetlands are among the most threatened ecosystems due to human-induced activities and are disappearing rapidly. Further, despite the potential vulnerability of hillslope seep wetland to disturbances, and their criticality in relation to all year round provision of forage for livestock grazing, they are among the most poorly studied wetland systems. Using a social-ecological system framing, and drawing on a range of ecological and social sciences methods, this study shed light on ways in which an integrative approach can contribute to sustainable utilisation of hillslope seep wetlands in the Tsitsa River catchment in the Eastern Cape province of South Africa. The study specific objectives were to i) evaluate the performance of Floristic Quality Assessment Index (FQAI), WET-Health and Floristic Assessment Quotient for Wetlands Index (FQAWet) indices for assessing hillslope seep wetlands ecological health ii) develop a trait-based approach for assessing the potential resilience and vulnerability of hillslope seep wetland plant species to disturbances, iii) assess the role of hillslope seep wetlands in the local communities in relation to livestock, and explore understanding of local people about the value of hillslope seep wetlands, iv) demonstrate collaborative insights emerging from an integrative social-ecological system research process to inform sustainable management of hillslope seep wetlands. A total of 11 hillslope seep wetlands were visually classified based on the level of erosion. Plant species composition within the wetlands was determined along a 100 m line transects across the hillslope wetland sites. 5 quadrats of 0.2m2 were also placed along transect for vegetation collection and cover. The plant species collected were used to calculate (FQAI) and FQAWet scores to evaluate the condition of hillslope seep wetlands. The degree of human disturbances was assessed using the Anthropogenic Activity Index (AAI), an index for qualitatively assessing the degree of human disturbance based on visual inspection of a wetland site. Factors represented in the AAI, include: (i) surrounding land use intensity; (ii) soil disturbance; (iii) hydrological alteration; (iv) habitat alteration within wetland; (v) vegetation community quality. The vegetation samples were collected in summer 2016 and winter 2017. All assessed indices were regressed against AAI to evaluate their performances. All assessed indices FQAI, FQAWet and WET-Health showed that hillslope seep wetland were impacted by human activities. FQAIall and WET-Health showed the strongest response to AAI in winter, while FQAIdom and FAQWet showed a weak response to AAI in all seasons. Overall, the findings of this study suggest that FQAIall and WET-Health are potentially better tools for assessing the biological conditions of hillslope seep wetland in South Africa. A novel trait-based approach was developed using seven plant traits and 27 trait attributes. Based on the developed approach, plant species were grouped into three potentially vulnerable groups in relation to grazing pressure. It was then predicted that species belonging to the highly vulnerable group would be less dominant at the highly disturbed sites, as well as in the winter season when grazing pressure is at its highest. The result corresponds largely with the seasonal predictions; however this was not the case for sites. The approach developed in this study worked and it was useful for predicting the potential responses of plant species in hillslope seep wetlands to grazing pressure. The success of the approach seasonally could be attributed to the careful selection of the traits, reflecting the mechanistic relationship between the grazing mode of stress on vegetation and trait-mediated biotic response. However, this still need to be refined using accurate vegetation cover methods that might have had impact on the lack of correspondence within sites. The results of the present study revealed that communities largely perceive hillslope seep wetlands as important ecosystems for their livelihoods. They recognise that the importance stems from services provided by the wetlands, particularly for livestock grazing during the dry season. Although hillslope seep wetlands are viewed as important ecosystems for livelihoods, the communities also perceive these wetlands as highly eroded ecosystems. Community members indicate willingness to strengthen local natural resource governance systems, which could lead to better management of hillslope seep wetlands. A range of protective strategies for hillslope seep were suggested by community members, including fencing, active herding and rotational grazing. The study suggests that active involvement of local communities is critical to the successful management of natural resources. The study highlights the need to consider the role of local people as influential components within social-ecological systems in order to promote effective management and conservation interventions of hillslope seep wetlands. Overall, the study highlights the criticality of an integrative social-ecological system approach for holistic management of hillslope seep wetlands within the studied catchment.
- Full Text:
- Date Issued: 2019
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