Browsing by Author "Mather, Andrew Alan."
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Item The risks, management and adaptation to sea level rise and coastal erosion along the Southern and Eastern African Coastline.(2012) Mather, Andrew Alan.; Garland, Gerald George.; Stretch, Derek Dewey.Sea level rise and coastal erosion are two processes which may result in major problems for coastal cities around the world. This is particularly true for Southern and Eastern African cities as they struggle to meet their developmental challenges in addition to sea level rise and coastal erosion. This thesis focuses on three main areas, the analysis of the rates of sea level from tide gauges in the region, the extent of wave run-up on the beach and the development of a simple technical and management framework that managers can apply to assess coastal hazards. The rates of sea level rise in the region vary, Zanzibar, Tanzania reflects a falling sea level at -3:64 plus minus 1:62 mm per year while the highest rate of sea level rise at Diego Garcia, British Indian Ocean Territories is +4:35 plus minus 7:61 mm per year. The rate of sea level rise are dependent on the complex interactions of vertical crustal movements, barometric pressure changes, and the warm Agulhas and cooler Benguela currents. Wave run-up is an indicator of the hazard zone. A number of international wave run-up models were assessed for use in this region and were found to be unsuitable. A new wave run-up model was developed which uses the bathymetric profile as opposed to the beach slope in predicting wave run-up. This model uses the equation Rx H0 = C S2=3, where Rx is the wave run-up height above Still Water Level, H0 is the significant wave height at the closure depth, C is dimensionless coefficient where median values are described by C ' 7:5, S is a representative nearshore slope (S = (hc=xh)). hc is the closure depth and xh the horizontal distance from the waters edge to the closure depth. An assessment of the impacts of sea level rise and wave run-up was undertaken based on a detailed case study of the Durban coastline. The results were incorporated into a standalone freeware viewer tool enabling this information to be accessible to planners, decision makers and the general public. The research has identifed several types of shoreline that are vulnerable to coastal erosion, sea level rise and extreme wave events. Recommendations as to what adaptation measures could be undertaken for the different beach types are proposed. With this information coastal managers and decision makers charged with managing shorelines can take the first step in understanding and adapting into the future.Item A study investigating impacts of sea level rise on coastal ecosystem services along the eThekwini Municipality coastline as a consequence of climate change and recommendations to build/enhance resilience.(2022) Petersen, Carla Bianca.; Pillay, Srinivasan Seeni.; Mather, Andrew Alan.; O’Donoghue, Sean.Climate change during the 21st century is caused by the rapid increase in global warming because of human activity. The consequences of climate change include melting glaciers, rising sea levels, and extreme weather. The primary cause of global sea level rise (SLR) is melting of ice on land, followed by ocean thermal expansion. Extreme events are happening more often and are becoming more intense due to greenhouse gas emissions from human activities. Coastal ecosystems are exposed to SLR and its physical impacts, such as flooding or salinisation, which in turn increase ecosystems’ vulnerability and decrease their ability to support livelihoods and provide ecosystem services such as coastal protection. Coastal ecosystems are also highly vulnerable to human-mediated drivers of climate change, such as land use change and coastal squeeze, because they are situated in the sea-land interface area that is favourable for urbanisation and development. This study focuses on the impacts of SLR on coastal dunes, and a protected tree species, Mimusops caffra, commonly known as coastal red milkwood, naturally occurring in part of the coastal forest in eThekwini Municipality. It further provides recommendations to enhance resilience along the Durban coastline. The results from the Coastal Vulnerability Index (CVI) analysis, classification of land use, developments impacted by a 300mm analysis, and the risk assessment of coastal ecosystems conclude that future SLR impacts will pose a threat to land demarcated under the Durban Metropolitan Open Space System, National Freshwater Ecosystem Priority Areas, and protected areas, as well as affluent high costing properties and coastal dunes and forests respectively, by a 300mm SLR along the eThekwini coastline in the next ±111 years if the current rate of SLR for Durban (2.74 mm/yr) remains constant. Further, whilst prior research suggests that the dieback of Mimusops caffra (M. caffra) is strongly related to fungal infections, results from this study indicate that M. caffra growing closest to the sea are stressed by environmental factors either wind or surge, thus increasing fungal infection as well. There is, however, little research on the impact of salt spray on these trees. Hence it is recommended that further investigation is required on milkwood to better understand the dieback observed in this study (i.e., due to fungus, or natural cause), especially as they are a protected species. Adaptation measures must be considered in areas identified as “high” risk for the protection of development from future SLR impacts, as well as maintaining natural areas where biophysical functionality is unhindered. From the CVI analysis, the regions which contain developments (i.e., private property) within the 100m HWM, both local government and homeowners should consider working together when installing geofabric sandbags to avoid increasing the effects of coastal erosion, as risks can be relocated elsewhere along the EM coast if individual action is not coordinated. From the classification of land use assessment, all areas within the respective land use that fall within the high-risk zone, the EM setback lines in conjunction with ecosystem-based adaptation should be implemented in order to protect these areas and ensure the functions of each land use is not unhindered. From the analysis of developments potentially impacted by future SLR, the total amount of estimated value of property loss within the given suburbs can assist coastal managers with deciding how money should be spent on defending properties and will yield the most protection from future SLR impacts along the EM coastline (i.e., a cost-analysis approach). Lastly, from the risk assessment of coastal ecosystems, future research on applying the vegetation index to certain parts of the EM coastline is necessary to get a better understanding of how vulnerable coastal ecosystems are to SLR impacts in Durban.