A spatial analysis of the threats to water quality of freshwater ecosystem priority areas in the upper crocodile catchment
Date
2018
Authors
Enoch, Candace
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Abstract
Freshwater ecosystems are under increasing pressure to sustain their functions on both a global and local scale. In light of growing concern regarding the pollution of South African rivers, this study focused on identifying potential threats to water quality of freshwater ecosystem priority areas (FEPAs) within the Upper Crocodile catchment. Nine sample sites located within five river FEPAs were selected for investigation and included the Skeerpoort, Sterkstroom, Buffelsfontein, Magalies and Brandvlei rivers. In situ measurements were taken of temperature, electrical conductivity, dissolved oxygen and pH using a YSI multi-parameter instrument. Water samples were collected at each site for the chemical analysis of nitrate, chloride, sulphate and phosphate. Biological samples were collected at four of the nine sites using SASS version 5 methodologies for biomonitoring.
Through the integration of water quality and land use data, key land use predictors of water quality within rivers FEPAs were identified. Principle component analysis revealed anthropogenic pollution sources including urban, agricultural, industrial, domestic and mining land use activities within the study area. The application of multiple linear regression showed that percentage improved grassland statistically significantly predicted autumn nitrate, winter chloride, autumn phosphate and summer dissolved oxygen across all FEPAs. Percentage urban land use was found to significantly predict autumn electrical conductivity and autumn phosphate levels within sample catchments. Percentage mines was the key predictor of sulphate concentrations. Forest plantations, cultivated and degraded thicket land use classes were not significant predictors of water quality within the study area.
The research concluded that improved grassland, urban and mining land use activities were the key predictors of water quality and represent potential threats to water quality of FEPAs within the Upper Crocodile catchment. It is recommended that water resource practitioners integrate FEPA maps and guidelines into planning processes in order to ensure sound management of freshwater ecosystems. Furthermore, the inclusion of FEPA sites into national water quality monitoring programmes and water resource management efforts will allow for river FEPAs to remain in good ecological condition.
Description
A dissertation submitted in partial fulfilment of the requirements for the degree of Master of Science to the Faculty of Science, University of the Witswatersrand, Johannesburg, 2018
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Citation
Enoch, Candace (2018) A spatial analysis of the threats to water quality of freshwater ecosystem priority areas and fish support areas within the upper crocodile catchment, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/25756