Browsing by Author "Locke, Kent"

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    Estimating minimum thresholds of natural vegetation for the integrated management and protection of water quality in South African catchments
    (2025) Locke, Kent; Winter, Kevin
    Despite multi-level commitments to Integrated Water Resources Management (IWRM), many of South Africa's water quality problems are attributable to the negative impacts of anthropogenic land use on water quality. Academics and policymakers have warned that unless action is taken to improve water resources management through the implementation of coordinated, proactive, and data-driven strategies, the country faces a water crisis that will have severe socio-ecological consequences. As natural vegetation acts as a sink, thus protecting water resources from diffuse pollution, the preservation of an adequate amount within catchment areas is important. However, among several pertinent questions, it is not clear (1) how much natural vegetation cover is required, (2) at which scale(s) this would be most effective, (3) how natural vegetation should be classified, and (4) whether the fragmentation of natural vegetation is a significant factor. To answer these questions, regression analysis was used to model relationships between water quality (measured using a composite pollution index) and metrics of natural vegetation (estimated from national land cover maps) at multiple scales across a sample of sub-catchments located within South Africa's Berg-Olifants, Breede-Gouritz, and Mzimvubu-Tsitsikamma Water Management Areas. Across this sample, a statistically significant, nonlinear, and inverse relationship was found between proportions of natural vegetation cover and pollution levels. This relationship was strongest (1) when natural vegetation was defined as an aggregation of indigenous woody vegetation, wetlands, and forestry plantations, and (2) when measured across the whole catchment and within a 200 m riparian buffer zone. At both scales, however, fragmentation was not found to be significant. The models further indicated that approximately 82 to 90% natural vegetation cover was necessary at these scales to keep pollution scores within acceptable levels. Additional nonlinear thresholds estimated using breakpoint analysis also suggested that if proportions of natural vegetation fall below 45% (across the whole catchment) and 60% (within a 200 m riparian buffer zone) a dramatic increase in pollution levels can be expected. The study has direct relevance for IWRM in so far as these results demonstrate (1) the critical importance of preserving areas of natural vegetation for water quality management and (2) the possibility of providing actors with quantifiable and context-specific management targets which can inform multistakeholder decision-making processes at appropriate spatial scales.
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    Open Access
    A study of an integrated management initiative to improve the Berg River, Western Cape, South Africa
    (2016) Locke, Kent; Winter, Kevin
    Integrated Water Resource Management (IWRM) is acclaimed as an important paradigm in the sustainable management of water resources. While the logic of IWRM is largely undisputed, it is often criticised for lacking sufficient guidance on its practical implementation. The gap between theory and practice in IWRM is mainly attributed to divergent interpretations of integration and how implementation should be practically pursued in water governance regimes. This research contributes to the on-going discussion around IWRM by investigating an integrated management initiative in the Berg River Catchment, in the Western Cape, South Africa. The Berg River Partnership (BRP) is a collective of government and non-government actors and stakeholders working together in an effort to improve the Berg River. The Berg River is a socially and economically important water system within the region, supporting a number of crucial industries. The Berg River is also under serious environmental stress due to polluted urban runoff, wastewater effluent discharges, agricultural runoff and the presence of alien invasive flora. The Management and Transition Framework (MTF) is adopted in this study as the framework that underpins the structured analysis of the Berg River Partnership, allowing the principles of IWRM to be identified and assessed in the governance structures and processes of the BRP. The study demonstrates how some principles of IWRM are practically implemented within the Berg River Partnership, while confirming some of the limitations of implementing IWRM.