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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Factors influencing wetland distribution and structure, including ecosystem function of ephemeral wetlands, in Nelson Mandela Bay Municipality (NMBM), South Africa

Melly, Brigitte Leigh, Gama, Phumelele T January 2016 (has links)
The Nelson Mandela Bay Municipality (NMBM) is a semi-arid area along the southern coastline of South Africa (SA). Until recently, there was no systematic approach to research on wetland systems in the NMBM. The systematic identification of wetlands was made more difficult by the relatively large number of small, ephemeral systems that can be difficult to delineate. This has meant that fundamental knowledge on wetland distribution, structure and function has been limited and, consequently, management and conservation strategies have been based on knowledge on systems from other regions of the country. Environmental processes occur at different spatial and temporal scales. These processes have an effect on the abiotic factors and biotic structure of wetlands, resulting in inherently complex systems. The location of the NMBM provides a good study area to research some of these environmental and biological attributes at different spatial scales, due to the variability in the underlying geology, geomorphology, vegetation types and the spatial and temporal variability in rainfall, within a relatively small area of 1951 km2. Thus, the aim of this study was to determine the factors influencing wetland distribution, structure and ecosystem functioning within the NMBM. The first Research Objective of work presented here was to identify wetlands using visual interpretation of aerial photographs. A total of 1712 wetlands were identified within the NMBM using aerial photographs, covering an area of 17.88 km2 (Chapter 5). The majority of these wetlands were depressions, seeps and wetland flats. Valley bottom wetlands (channelled and unchannelled) and floodplain wetlands were also identified. A range of wetland sizes was recorded, with 86% of the wetlands being less than 1 ha in size and the largest natural wetland being a floodplain wetland of 57 ha, located south of the Swartkops River. The identified wetlands were used to create a wetland occurrence model using logistic regression (LR) techniques (Chapter 5), in accordance with Objective 2 of the study. An accuracy of 66% was obtained, which was considered acceptable for a semi-arid climate with a relatively high degree of spatial and temporal rainfall variability. The model also highlighted several key environmental variables that are associated with wetland occurrence and distribution at various spatial scales. Some of the important variables included precipitation, evapotranspiration, temperature, flow accumulation and groundwater occurrence. Wetland distribution patterns were described in Chapter 6. Spatial statistics were used to identify whether wetlands are clustered and, therefore, form mosaics within the surrounding landscape (Objective 3). Systems were found to be highly clustered, with 43% of wetlands located within 200 m of another system. Clustering and wetland presence was especially prominent in the southern portion of the Municipality, which is also associated with a higher mean annual precipitation. Smaller wetlands were also significantly more clustered than larger systems (Average Nearest Neighbour statistic, p-value < 0.0001). Average distances also significantly varied according to HGM type, with depressions being the most geographically isolated wetland type compared to the other HGM types. Overall, distances between wetlands indicated good proximal connectivity. Potentially vulnerable areas associated with wetland systems were identified successfully using landscape variables, in accordance with Objective 4. These variables were: land cover, slope gradient, flow accumulation, APAN evaporation, mean annual precipitation (MAP) and annual heat units. The existing Critical Biodiversity Network was also used in connection with these variables to further identify potentially vulnerable areas. The abiotic and biotic characteristics were decribed for three hydrogeomorphic (HGM) types at a total of 46 wetland sites (Chapter 7), as per Objective 5. Depressions, seeps and wetland flats were sampled across the different geological, vegetation and rainfall zones within the NMBM. The wetland sites were delineated up to Level 6 of the Classification System used in SA, and the various abiotic and biotic characteristics of these systems were defined. A total of 307 plant, 144 aquatic macroinvertebrate and 10 tadpole species were identified. Of these species, over 90 species were Eastern Cape and SA endemic species, as well as three threatened species on the IUCN Red List. Multivariate analyses (including Bray-Curtis similarity resemblance analyses, distance-based redundancy analyses, SIMPER analyses and BIOENV analysis in Primer), together with environmental data, were used to define community structure at an HGM level, in accordance with Objective 5. The importance of the spatial scale of the environmental data used to define plant and macroinvertebrate community structure was described in Chapter 7, to address Objective 6. The results showed that both broad-scale and site-level characteristics were important in distinguishing community structure within the HGM types that superseded general location, the sample timing or the stage of inundation. These results also indicated that a combination of both landscape and site-level data are important in defining the community structure in the various HGM types. Some of the important environmental variables that explained some of species assemblages were similar to those in the wetland occurrence model (Chapter 5), with some additional hydrological and soil physico-chemical parameters (e.g. soil electrical conductivity, soil pH, and surface and subsurface water nutrients). These significant variables indicate the complex, multi-scalar role of environmental attributes on wetland distribution, structure and function.
2

An investigation into the effect of metals on chlorophyll content and photosynthesis activity of the wetland plant phragmites australis in the lower Diep River, Milnerton, Cape Town

Ayeni, Olutoyosi Olaide January 2011 (has links)
Thesis (MTech (Environmental Management)))--Cape Peninsula University of Technology, 2011. / A study involving a wetland plant, common reed (Phragmites australis L.) was carried out along the bank of the lower Diep River and the adjacent soil samples from four different sites (Milnerton Lagoon, Lower Estuary, Milnerton Bowling Club and Woodbridge Island), Cape Town, South Africa. The aim was to determine the extent of metal contamination and its impact on physiological indices. Results showed that among the metals evaluated, AI and Fe were consistently higher in all the soil samples (from both river bank and the adjacent soil) followed by Zn, Mn, Pb, Cu, Cd, Co, Cr and Ni. The concentrations of AI in the river banks ranged between 1214.1 - 3176 mg.kg-1 compared with the adjacent soils, where AI concentration ranged from 434.8 - 2445.4 mg.kq". The Fe concentrations from the river bank values ranged from 1136.4 - 4897.2 mg.kg-1 compared with Fe concentrations of the adjacent soil samples which ranged from 402.2 - 2459.8 mg.kg-1 . Generally, Zn ranged from 2.4 - 211.5 mq.kq"; Mn: 5.5 - 48.05 mg.kq': Pb: 0.97 - 71.7 mg.kq"; Cu: 0.3 - 45.9 mg.kq'; Cd: 0.0 - 9.3 mg.kq": Co: 0.2 - 2.7 mg.kq': Cr: 0.3 - 2.1 mg.kg-1 ; and Ni: 0.02 - 2.6 mg.kg-1. Overall, Ni had the lovest concentrations in the ecosystem. Results also showed that the abundance of metals from plant samples were in the order of AI > Pb > Cd > Co > Ni > Cr; and for micronutrients, Fe > Mn > Zn > Cu both in the shoots and roots sampled from all the sites investigated. The values of chlorophylls a, b and total chlorophyll as well as photosynthesis were significantly higher in the P. australis plant samples and from the adjacent soil compared with those from the river bank. These results suggest that contamination of soils and wetland ecosystem by metals over and above plant requirements may affect the chlorophyll and photosynthesis rate of the plant thereby undermining the physiological functioning of plants growing along river systems.
3

The effect of land use on the species composition of amphibians in North Eastern KwaZulu-Natal.

Russell, Charlene. January 2010 (has links)
Global declines in amphibian species have directed research towards investigating why this is happening. One of the major causes of these declines is the fragmentation and loss of habitat. This study examined the effect of land use on the species composition of frogs within North Eastern KwaZulu-Natal, and the use of buffer zones to facilitate the protection of these species. Three land use types were investigated: sugar cane (Saccharum officinarum), gum (Eucalyptus sp.) plantations and conservation areas. The average number of frog species differed between areas: conservation 13.2 ± 6.6; plantations 3.8 ± 1.3; and sugar cane 2.8 ± 1.4. Sugar and gum plantation were found to be lacking the wetland and grassland/woodland habitats. In addition to this, the frog species that were not present on these land use types were those that are totally dependent on water as well as those that are not dependent on a water source. Two species were highlighted as possible indicator species of land use: Amietophrynus gutturalis and Hyperolius marmoratus. To mitigate the effect of these land use types, the use of buffer zones was explored in a desktop study. A range of buffer zones were applied to wetlands in a sample study area, using a range of distances including the distances of 290 m and 159 m recommended by Semlitsch and Bodie (2003), and the recommended distances for wetlands in South Africa of 10-20 m. The application of a 290 m and 159 m buffer zone on a conglomerate of wetlands connected by a 100m buffer was the most feasible as it incorporated a percentage of the total study (6.4% and 4.3%) area similar to the percentage occupied by the recommended 20m buffer zone (5.5%) around all wetlands, and still incorporated the range under protection put forward by Semlitsch and Bodie (2003). Management implications of these findings are discussed. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
4

Hydrological proceses, chemical variability, and multiple isotopestracing of water flow paths in the Kudumela Wetland- Limpopo Province, South Africa

Mekiso, Feleke Abiyo January 2011 (has links)
The hydrology of the Kudumela Wetland, Limpopo Province of South Africa was studied from November 2005 to April 2007, involving both fieldwork and laboratory analyses. This study presents the results of an investigation of the hydrology of the Kudumela Wetland in South Africa, and its contribution to dry season flow in the Mohlapitsi and Olifants Rivers. Initially, 40 Piezometers were installed along seven transects and water levels monitored in order to understand water table level characteristics (fluctuations) with time. Water levels in transects one, three, the right bank portion of transect four and transect six showed fluctuations. Transect two, the left bank portion of transect four and transect five did not show significant temporal changes. The relationships between piezometer water levels, rainfall in the study area and stream flow observed at a river gauging station are not clear. The river within the wetland is a gaining stream because the water table level elevation is above that of the river. This indicates that the wetland is feeding the river. The northern part of the wetland (T1 and T2) is affected by artificial drains and most of the piezometers closest to the river channel showed the lowest variations. The relationships between rainfall, groundwater, and surface water at this site shows that stream flow did not respond quickly to precipitation as expected, even in months when rainfall increased (for example, 74 and 103mm during 08/02/06 and 18/02/06 respectively), and the groundwater levels did not show fluctuations, indicating that groundwater responds gradually to precipitation, and that the relationship between rainfall, groundwater and surface water is complex. The environmental stable isotopes (deuterium and oxygen-18) and the radioactive isotope (tritium) were analyzed, along with field observations of electrical conductivity (EC), pH, total alkalinity (Talka) and some major and minor dissolved ion analyses for tracing water dynamics in the study area. A total of 39 water samples was taken and analyzed from boreholes, auger holes, right bank and left bank drains, various points along the river and springs in four sampling visits to the wetland. The results did not clearly provide a temporal record of isotope and chemical variations in the various sources. Results from the most extensive sampling survey in April 2007 provide the most comprehensive overview of hydrological relationships. Clustering of the stable isotope data suggests that the water samples of upstream and downstream river, auger holes further south and most drains clustered together suggesting a common water source and almost all samples fall above the global (GMWL) and local (Pretoria MWL) meteoric water lines, while some fall between the global and Pretoria meteoric water lines. Six representative water samples were analyzed for major ion concentration. Both cation (Ca, Mg, K, and Na) and anion (HCO3, SO4, Cl, and NO3) analyses in November 2007 confirmed conclusions reached from field observations. The analysis shows that a single type of water (Ca, Mg-HCO3) is involved in the study area. In almost all major ion plots, the right bank drains, upstream river and downstream river samples grouped together in a single cluster. As the means for reliable river flow measurements were not available, except for the gauging station at the outlet of the valley, rough, semi-quantitative estimates were made during several field visits. These, suggest considerable losses of river flow into the gravel/boulder beds at and below a gabion dam at the head of the valley. Three major and several other left bank springs and right bank drains at transects T1 and T2 contributed to the river flow at all times. Along with the isotopic and chemical evidence, these observations have lead to a hypothesis that river water enters the wetland and flows back to the Mohlapitsi River through boulder beds underlying the wetland and through drains on the surface of the argillaceous aquitard covering the more conductive boulder beds. Deeper dolomitic groundwater does not appear to contribute to the water balance at least in the northern half of the wetland. Although environmental isotope and hydrochemistry results may not unequivocally prove this hypothesis they do not contradict it.
5

An investigation into the socio-economic factors and community perception in the direction of the conservation and management of the wetland : a case study of Thohoyandou Block F.

Ndou, Avhatakali Christopher 30 October 2012 (has links)
MPM / Oliver Tambo Institute of Governance and Policy Studies
6

Can expansive (social) learning processes strengthen organisational learning for improved wetland management in a plantation forestry company, and if so how? : a case study of Mondi

Lindley, David Stewart January 2014 (has links)
Mondi is an international packaging and paper company that manages over 300 000 ha of land in South Africa. After over a decade of working with Mondi to improve its wetland management, wetland sustainability practices were still not integrated into the broader forestry operations, despite some significant cases of successful wetland rehabilitation. An interventionist research project was therefore conducted to explore the factors inhibiting improved wetland management, and determine if and how expansive social learning processes could strengthen organisational learning and development to overcome these factors. In doing so, the research has investigated how informal adult learning supports organisational change to strengthen wetland and environmental sustainability practices, within a corporate plantation forestry context. How individual and/or group-based learning interactions translate to the collective, at the level of organisational change was a key issue probed in this study. The following three research questions were used to guide the research: 1. What tensions and contradictions exist in wetland management in a plantation forestry company? 2. Can expansive learning begin to address the tensions and contradictions that exist in wetland management in a plantation forestry company, for improved sustainability practices? 3. Can expansive social learning strengthen organisational learning and development, enabling Mondi to improve its wetland sustainability practices, and if so how does it do this? Cultural historical activity theory (CHAT) and the theory of expansive learning provided an epistemological framework for the research. The philosophy of critical realism gave ontological depth to the research, and contributed to a deeper understanding of CHAT and expansive learning. Critical realism was therefore used as a philosophy to underlabour the theoretical framework of the research. However CHAT and expansive learning could not provide the depth of detail required to explain how the expansive learning, organisational social change, and boundary crossings that are necessary for assembling the collective were taking place. Realist social theory (developed out of critical realism by Margaret Archer as an ontologically located theory of how and why social change occurs, or does not) supported the research to do this. The morphogenetic framework was used as a methodology for applying realist social theory. The expansive learning cycle was used as a methodology for applying CHAT and the theory of expansive learning; guiding the development of new knowledge creation required by Mondi staff to identify contradictions and associated tensions inhibiting wetland management, understand their root causes, and develop solutions. Through the expansive learning process, the tensions and contradictions become generative as a tool supporting expansive social learning, rather than as a means to an end where universal consensus was reached on how to circumvent the contradictions. The research was conducted in five phases: • Phase 1: Contextual profiling to identify and describe three activity systems in Mondi responsible for wetland management: 1) siviculture foresters; 2) environmental specialists; 3) community engagement facilitators. The data was generated and analysed through through document analysis, 17 interviews, 2nd generation CHAT analysis, and Critical Realist generative mechanism analysis; • Phase 2: Analysis and identification of tensions and contradictions through a first interventionist workshop. Modelling new solutions to deal with contractions, and examining and testing new models in and after the second interventionist workshop; • Phase 3: Implementing new models as wetland management projects and involved project implementation. This included boundary crossing practices of staff in the three activity systems, reflection and re-view in a further five progress review/interventionist workshops, and a management meeting and seminar; • Phase 4: Reflecting on the expansive learning process, results, and consolidation of changed practices, through nine reflective interviews and field observations; • Phase 5: Morphogenic/stasis analysis of the organisational change and development catalysed via the expansive social learning process (or not). The research found that expansive social learning processes supported organisational learning and development for improved wetland management by: 1) strengthening the scope, depth, and sophistication of participant understanding; 2) expanding the ways staff interact and collaboratively work together; 3) democratising decision making; 4) improving social relations between staff, reducing power differentials, and creating stronger relationships; 5) enhancing participant reflexivity through deeper understanding of social structures and cultural systems, and changing them to support improved wetland and environmental practice of staff, and developing the organisational structures and processes to strengthen organisational learning and development; and 6) using the contradictions identified as generative mechanisms to stimulate and catalyse organisational learning and development for changed wetland/environmental management.
7

Spatial variation in modelled hydrodynamic characteristics associated with valley confinement in the Krom River wetland: implications for the initiation of erosional gullies

Schlegel, Philippa Kirsten January 2018 (has links)
Gully erosion is a significant and widespread feature of southern African wetlands, including the wetlands of the Krom River, Eastern Cape. Gully erosion in wetlands is consistently being viewed as a major contributing factor to wetland degradation and eventual collapse. Many gullies exist in the Krom River and Working for Wetlands has spent large sums of money to stabilise head-cuts with the expectation that further erosion would be halted and possibly avoided altogether. Observations in the Krom River wetlands have revealed that most gullies in the wetland are initiated where the width of the trunk valley has been reduced as a consequence of deposition by tributary alluvial fans that impinge on the trunk valley and reduce its width. The aim of this study was to examine variation in hydrodynamic characteristics for a range of discharges, as flow in the broad Kompanjiesdrif basin (~250 meters wide) is confined in a downstream direction to a width of less than 50 meters by a combination of a large impinging left bank tributary alluvial fan that coincides with a resistant bedrock lithology. The study was done by collecting topographical survey data using a Differential Global Positioning System in order to create a Digital Terrain Model with a suitable resolution. Flow was recorded using a Marsh-McBirney Model 2000 Flo-Mate as well as recording the flood extent for each flow condition; this was used in the calibration process of the model. Vegetation measurements were conducted in order to calculate a roughness value across the valley floor. A two-dimensional raster based flood inundation model, CAESAR-Lisflood and a one-dimensional hydraulic analysis model, HEC-RAS, were then used to simulate different parameters associated with variation in discharge, including flow velocity, water depth and stream power, thereby creating a better understanding of the hydraulic characteristics that may promote the formation of gullies in the wetland. Based on these hydraulic analyses it is evident that the effect of impinging alluvial fans on hydraulic characteristics such as flow velocity, water depth and stream power, may lead to the initiation of gullies within the Krom River wetland. This work improves understanding of the collapse of palmiet wetlands in steep-sided valleys within the Cape Fold Mountains of South Africa, and can aid in wetland management.
8

South Africa’s response in fulfilling her obligations to meet the legal measures of wetland conservation and wise use

Lemine, Bramley Jemain January 2018 (has links)
Thesis (MTech (Environmental Management))--Cape Peninsula University of Technology, 2018. / South Africa is a signatory to the Convention on Wetlands of International Importance especially as Waterfowl Habitat of 1971 (referred to as the Ramsar Convention), which is an international convention making provision for protection and wise use of wetlands. Article 3 of the Ramsar Convention requires signatories to formulate and implement their planning to promote wise use of wetlands within their jurisdiction. “Wise use of wetlands” is defined as “the maintenance of their ecological character, achieved through the implementation of ecosystem approaches, within the context of sustainable development” (Birnie & Boyle, 2009: 674). The concept of wise use has been interpreted to mean sustainable development (de Klemm & Shine, 1999: 47; Birnie & Boyle, 2009: 49; Kiss & Shelton, 2007: 93; Birnie & Boyle, 2009: 674; Sands, 2003: 604), as it pertains to wetlands. Having said this, the National Environmental Management Act 107 of 1998 (NEMA) sets out principles of sustainable development that every organ of state must apply in the execution of their duties. Due to the wise use-sustainable development link, two NEMA principles have been considered to form the basis of this study, i.e. sections 2(4)(l) and 2(4)(r). The first principle places an obligation upon the state to ensure that there is intergovernmental coordination and harmonisation of policies, legislation and action relating to the environment (read to include a wetland); and the second principle is to ensure that specific attention in the management and planning are had to wetlands. Ironically, factors that are identified as hindering wise use include, but are not limited to: conflicting and incomplete sectoral law, absence of monitoring procedures, the absence of legal measures for environmental management of water quantity and quality. Therefore, an analysis will be undertaken to determine the extent to which South Africa’s legislative framework regulating wetland conservation is fulfilling the requirements for the promotion of wise use, through these two principles. Focus was had to environmental and related legislation, policies and regulations that promote and/or constrain wetland conservation and wise use. This study identifies the flaws within the law; and proposes streamlining and, where apposite, amendments to the existing legislative framework regulating wetlands in order for South Africa to fulfil her obligations.
9

A review of stakeholder interests and participation in the sustainable use of communal wetlands: the case of the Lake Fundudzi catchment in Limpopo Province, South Africa

Silima, Vhangani January 2007 (has links)
Many rural South African people depend on natural resources for their survival. Wetlands provide some of those natural resources. These are presently are under pressure due to high demand, overexploitation and poor land management. The history of South Africa has been characterised by exclusion of local communities in the process of decision-making and general management of natural resources. Participation of all stakeholders is crucial for successful sustainable natural resource management. Various South African departments are engaged in a number of strategies for promoting meaningful participation of local communities. The South African laws promoting protection and sustainable use of natural resources incorporate democratic principles that require high level of participation from resource users, local communities in particular. Most of the participation techniques used are focused on satisfying political mandates and do not respond to the social context of the resource users. The aim of the study was to review the participation of stakeholders in the project of promoting the sustainable use and protection of the Lake Fundudzi catchment. The idea was to probe stakeholder interests more carefully, and to research tensions that arise in the participation process, using qualitative methodologies. Through the use of questionnaires, observations and document analysis stakeholders’ interests were identified to assess their influence in the process of participation of local stakeholders. The review of stakeholders’ participation in the Lake Fundudzi Project showed that stakeholders’ interests are crucial for meaningful local community participation, communication and education influence. They enable meaningful participation and empowerment. A multi-stakeholders approach enables stakeholders to share roles and responsibilities and the participation process offers an opportunity for local stakeholders to participate democratically in the Project. Power relations affect stakeholder participation, capital dependant participatory initiatives are likely to be at risk, participatory processes are likely to promote the empowerment and knowledge exchange amongst stakeholders, the views of local stakeholders are not always considered by outside support organisation and multi-stakeholder participatory approaches enable the initiative/activity/project to achieve its objectives.
10

Natural mechanisms of erosion prevention and stabilisation in a Marakele Peatland ; implications for conservation management

Bootsma, Antoinette Alexandra 12 1900 (has links)
The Matlabas mire, an actively peat accumulating wetland, is located in the headwaters of the Matlabas River, Marakele National Park, Limpopo Province, South Africa. Various seepage zones and artesian peat domes are contained in this peatland that consists of two tributaries of which the western one is partially channelled. The occurrence of decaying peat domes and desiccated areas with terrestrial vegetation, as well as the apparent erosion on the western tributary, have raised concerns on the health of this wetland. A network of piezometers was installed in the mire and results confirm that the system is fed primarily from seepage from the slopes of the catchment. Chemical analysis and temperature recorded indicate an isolated groundwater source of which the water does not mix with surface water. This is linked with isotope analysis of the age of peat in various sections of the mire. Erosion was attributed to anthropogenic changes in the catchment. Management recommendations include rehabilitation and reinstating the driving forces that support the mire. / Environmental Sciences / M. Sc. (Environmental Management)

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