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University of KwaZulu-Natal (2018)

Assessment of spatial and temporal variation in water quality of the Pienaars River, Limpopo water management area.

Mlotshwa, Lungile Wendy.

Titre : Assessment of spatial and temporal variation in water quality of the Pienaars River, Limpopo water management area.

Auteur : Mlotshwa, Lungile Wendy.

Université de soutenance : University of KwaZulu-Natal

Grade : Master of Science In Ecological Science 2018

Résumé
The Pienaars River is a major tributary of the most important river system in Gauteng and South Africa in general, the Crocodile River. The Crocodile River catchment is one of the most deteriorated catchments in the country. It is a hub for various detrimental economic activities which contribute significantly to the country’s economy. Some of these activities are sources of contaminants polluting the Pienaars River. The study assessed the water quality dynamics and conditions of the Pienaars River based on historical water quality data (1980-2015) and newly collected data from February 2017, both collected from eight different stations. For the new data, 16 parameters were analysed to assess the river’s water quality status and suitability for predominant uses. The historical data was obtained from the Department of Water and Sanitation database to assess spatial and temporal variation of 17 water quality parameters. The results indicated that the water quality fluctuated over the years. Some parameters, namely ; pH, TAL, DMS, K, KJEL-N and Si showed a significant deterioration over the years. A significant improvement was also observed in Cl- , DMS, EC, F, Mg, NO3+NO2-N, P-Tot, PO4-3 and SO4-2 over the years. The results also revealed spatial and temporal variation in water quality. The upstream catchment of the river is the most developed, and land use becomes more natural vegetated land with sparse dryland agricultural fields in the downstream catchment. The results revealed that Pienaars River receives a considerable amount of pollutants in the upstream reaches. The water quality further deteriorated towards the downstream reaches along the gradient as the river passes through different land uses. It was therefore concluded that the upstream reaches had significant impact on the river’s water quality. A significant seasonal variation in water quality was observed between summer, spring, autumn and winter. Generally, the water quality was better during the high flow period due to rainfall dilution effect. High-flow periods played a major role in not only regulating the pollution levels but the high runoff acted as a transporting mechanism for pollutants. Overall, DMS, TAL and Si displayed a strong seasonal variation whereas F was the least influenced by seasonality

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