Philosophiae Doctor - PhD (Earth Science)

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https://hdl.handle.net/10566/17483

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Browsing by Author "Dube, Timothy"

Now showing 1 - 5 of 5
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    Developing an integrated remotely sensed framework for the detection and monitoring of seasonally-flooded wetlands in semi-arid environments of southern Africa
    (University of the Western Cape, 2022) Gxokwe, Siyamthanda; Dube, Timothy
    Wetlands are among the most important ecosystems on earth; they cover approximately 4-6% of the earth’s surface and offer critical eco-hydrological services. However, these ecosystems are under threat from anthropogenic activities, droughts and climate variability, as well as from global environmental change. It is estimated that over 60% of the world’s wetlands have been lost due to climate change and variability, as well as other anthropogenic influences. There is, therefore, a need for their routine monitoring and assessment to ensure the sustainable use and management of these systems on a national, regional and local scale, and prevent their further degradation and loss. This study aimed at developing an integrated cloud-computing-based, remotely-sensed framework for the detection and monitoring of small and seasonally-flooded wetlands along the semi-arid Limpopo Transboundary River Basin of southern Africa, which was previously a challenging task when using the traditional assessment and monitoring methods.
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    Greywater reuse - An assessment of health and nutritional quality of home gardens produce in rural South Africa
    (University of Western Cape, 2021) Radingoana, Makgalake Pabalelo; Dube, Timothy
    The majority of rural communities in sub-Saharan Africa are predominantly poor and depend largely on small-scale subsistence farming. To date, various farming mechanisms (e.g. organic farming, crop rotation, agroforestry and inter-cropping) have been introduced to improve food security and to avert hunger; however, water scarcity remains a challenge. The sub-Saharan African region is currently regarded as water stressed and this has had a significant impact on rural livelihoods. Despite being considered as a water-scarce region, the demand for water for agricultural purposes continues to increase exponentially, while, on the other hand, its supply keeps on diminishing, particularly for agricultural production.
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    The impact of land use and land cover changes on wetland productivity and hydrological systems in the Limpopo transboundary river basin, South Africa
    (University of Western Cape, 2021) Thamaga, Kgabo Humphrey; Dube, Timothy
    Wetlands are highly productive systems that act as habitats for a variety of flora and fauna. Despite their ecohydrological significance, wetland ecosystems are under severe threat as a result of environmental changes (e.g. the changing temperature and rainfall), as well as pressure from anthropogenic land use activities (e.g. agriculture, rural-urban development and dam construction). Such changes result in severe disturbances in the hydrology, plant species composition, spatial distribution, productivity and diversity of wetlands, as well as their ability to offer critical ecosystem goods and services. However, wetland degradation varies considerably from place to place, with severe degradation occurring particularly in developing regions, such as sub-Saharan Africa, where Land Use and Land Cover changes impact on wetland ecosystems by affecting the diversity of plant species, productivity, as well as the wetland hydrology.
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    Spatial and temporal dynamics of flows and pools along non-perennial rivers in arid and semi-arid areas, South Africa
    (University of the Western Cape, 2023) Maswanganye, Sagwati Eugene; Dube, Timothy
    This study aimed to assess the use of multi-source remotely sensed data for monitoring the spatial distribution and dynamics of pools in two distinct sites (Touws and Molototsi) in South Africa. Various water extraction indices, including NDWI, Modified NDWI, and NDVI, were employed, along with a random forest classifier and Sentinel-1 SAR data, to map pools and their dynamics in both locations. The remote sensing methods effectively detected and mapped pools with satisfactory accuracy, except for small pools below 400 square meters. The study identified flow occurrences and rainfall as significant factors influencing changes in pool sizes. However, the interaction between pools and groundwater required further investigation and showed no conclusive evidence in this study.
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    Understanding Striga occurrence and risk under changing climatic conditions across different agroecological farming systems at local and regional scales122
    (University of Western Cape, 2020) Mudereri, Bester Tawona; Dube, Timothy
    The invasion by Striga in most cereal crop fields in Africa has posed an acute threat to food security and socioeconomic integrity. Consequently, numerous technological and research developments have been made to minimize and even control the Striga impacts on crop production. So far, efforts to control Striga have primarily focused on the manipulation of the genetics of the host crops, as well as understanding the phenological and physiological traits, along with the chemical composition of the weed.