>Magister Scientiae - MSc / Improved knowledge is required on the quantity and source of water resources, particularly evident during periods of drought currently being faced in South Africa. There is inadequate knowledge with regards to the flood attenuating properties of wetlands, particularly evident in the ungauged catchments of Southern Africa. This study aims to improve the knowledge on the contribution of flow from tributaries with headwaters in mountainous regions to low lying areas and the effects of wetlands on river flow patterns. Several river flow monitoring sites were established along the major upper tributaries of the Nuwejaars River at which daily water levels were recorded and bi-weekly discharge measurements were conducted. Weather data was collected using four automatic weather stations and three automatic rain gauges’ setup throughout the catchment. Rainfall data coupled with rating curves and daily discharges were used to assess the flow responses of these tributaries to rainfall events. Additionally, stable isotope analysis and basic water quality analysis was used to determine the major sources of flow within the major tributaries. The rainfall and river flow data collected, coupled with the characterization of the wetland was used to determine the flood attenuation capabilities of the wetland. Lastly, a conceptual model based on a basic water balance was developed to further explain the role of the wetland and its effects on river flows. The results showed a 27-hour lag time in peak flows from the upper tributaries at the inflows of the wetland to the outflow. Two of the upper tributaries had flow throughout the year and were fed by springs in the upper mountainous regions of the catchment and all tributaries were largely reliant on rainfall for peak flows. The temporary storage of flows within the wetland occurred as a result of the Nuwejaars River bursting its banks, filling of pools, or ponds and the Voëlvlei Lake. It was concluded that the wetland increased the travel time and decreased the magnitude of flows of the Nuwejaars River. However, due to the fact that wetlands are interlinked on a catchment scale and have a collective effect on flood attenuation this study may be improved by looking at the wetlands within the catchment holistically.

Wetlands are vital ecosystems providing essential services to both humans and the environment, yet they face threats from human activities leading to loss and disturbance. This study utilizes remote sensing (RS) methods, including object-based image analysis (OBIA), to map and assess wetland health in Kristianstad’s Vattenrike in the southernmost part of Sweden between 2015 and 2023. Objectives include exploring RS capabilities in detecting wetlands and changes, deriving wetland health indicators, and assessing classification accuracy. The study uses Sentinel-2 imagery, elevation data, and high-resolution aerial images to focus on wetlands along the river Helge å. Detection and classifications were based on Sentinel-2 imagery and elevation data, and the eCognition software was employed. The health assessment was based on the spectral indices Normalized Difference Vegetation Index (NDVI) and Modified Normalized Difference Water Index (mNDWI). Validation was conducted through aerial photo interpretation. The derived classifications demonstrate acceptable accuracy levels and the analysis reveals relatively stable wetland conditions, with an increase in wetland area attributed to the construction of new wetlands. Changes in wetland composition, such as an increase in open meadows and swamp forests, were observed. However, an overall decline in NDVI values across the study area indicates potential degradation, attributed to factors like bare soil exposure and water presence. These findings provide insights into the local changes in wetland extent, composition, and health between the study years.

Wetlands within South Africa are an important source of water and nutrients necessary for biological productivity and often the survival of the local people. In a country where the rural communities depend on wetlands for their day to day provision of water, food and materials it has become necessary to understand the functions within wetland systems, so that proper conservation measures can be applied in order to protect and ensure the sustainable use of wetlands. Due to the fact that South Africa has a semi arid climate, thereby affecting the availability of water it is sensible that studies are under-taken in which, more is explored about the water resources, the protection as well as the sustainable use of the wetlands within the region. Despite the fact that the total area which wetlands cover in South Africa is relatively small, the functions which they provide is of fundamental magnitude not only to wildlife but also as an essential part of the human life support system. Wetlands have the ability to regulate regional flow regimes and are often situated in areas of impeded drainage, which may contribute to the regulation of water. It is thus plausible that if headwater/palustrine wetlands are destroyed, many of the streams and rivers which under normal circumstance are perennial, would not only become non- perennial but the consequence of a drought would be far more severe, as well as increasing the risk in flood damage further down the river. In Giants Castle Game Reserve, situated in the KwaZulu-Natal Drakensberg, several palustrine wetlands where studied to identify the geomorphic attributes which contribute to the origin and maintenance of these wetlands. An added motive for the study was the fact that, according to Ramsar, one of the reasons for conserving the Drakensberg wetlands is to ensure the maintenance and production of water quality to KwaZulu-Natal. Seven wetlands within the Boesmans river upper catchment were identified and studied. Soil investigations were undertaken in an effort to determine the driving forces behind the origin and maintenance, as well as to improve the understanding relating to the functioning of the wetlands. The geomorphic attributes which were identified as being important to the genesis and maintenance of wetlands were found to be the following: low relief, soil piping within wetlands, sediment trapping ability of wetlands, the surface roughness of wetlands, channeling within wetlands, organic matter accumulation as well as geological barriers within wetland system. The adaptability of Longmore’s (2001) Hydro-Geomorphic classification to different catchment areas was also tested and was found suitable for these wetlands, although the influence of piping on wetlands evidently requires further investigation and incorporation into classifications. / Dissertation (MA)--University of Pretoria, 2006. / Geography, Geoinformatics and Meteorology / MA / Unrestricted

Made available in DSpace on 2015-03-05T16:19:35Z (GMT). No. of bitstreams: 0 Previous issue date: 27 / Nenhuma / O Parque Nacional da Lagoa do Peixe (PNLP), na zona costeira do Rio Grande do Sul, protege amostras importantes de quase todos os ecossistemas de áreas úmidas e espécies de aves aquáticas da região. Os movimentos migratórios e os deslocamentos entre áreas úmidas determinam importantes variações temporais de composição e abundância das assembléias de aves aquáticas. Os objetivos deste estudo foram descrever os padrões de composição e abundância de aves aquáticas em 27 áreas úmidas naturais, distribuídas no entorno do Parque Nacional da Lagoa do Peixe; descrever os padrões de variação temporal das assembléias associados às variações de pluviosidade; avaliar o efeito do tamanho dos fragmentos, do tipo de área úmida, do tipo de matriz circundante e da disponibilidade de áreas úmidas na paisagem na composição, riqueza e abundância de aves aquáticas e discutir a importância dos remanescentes de áreas úmidas do entorno do Parque para a conservação de aves aquáticas. Foram realizados 12 censos mensais de aves aquátic / The Lagoa do Peixe National Park (LPNP), in the coastal plain of Rio Grande do Sul, protect important samples of almost all wetland ecosystems and waterbird species in the region. The surrounding areas also harbor remnant natural wetlands, scattered in a matrix of drained meadows or rice fields, of which the conservation significance is unknown. The structure of waterbird assemblages in these remnants is expected to vary with their spatial attributes and with the characteristics of the surrounding matrix. The aim of this study was to describe the composition, richness and abundance of waterbird assemblages of 27 remnant wetlands; to describe the seasonal variation in the structure of these waterbird assemblages and it’s relation with pluviosity; to evaluate the effect of the remnant’s area, type of wetland, type of matrix and wetland availability in the landscape on the composition, richness and abundance of waterbirds; and to discuss the importance of the remaining wetlands nearby the Park for the conservat