| Summary: | M.Sc. === The goal of this study is to determine the relationship between landuse and runoff water quality. The chosen study area is the Roodeplaat Dam drainage basin. The basin contains three subbasins with varying characteristics. The western subbasin is that of the Hartbees Spruit with a largely urban character. The eastern subbasin containing the Edendal Spruit has mostly rural characteristics in terms of landuse. The central (and largest) sub-basin of the Pienaars River has a mixed (urban/rural) land usage. Specific aims of the study were the determination of the negative (or positive) influence of urban landuse on the quality of water that flows into the Roodeplaat Dam, and the determination of the influence of climate (more specifically precipitation) on this water quality. A review of different water quality components is provided with the emphasis on those used in the study. Each of the three subbasins are described in terms of landese to determine the possible influences on water quality. Water quality data obtained from the Department of Water Affairs (Pretoria) were calculated to fortnightly averages in order to obtain complete time series. Six inorganic water quality indicators (total dissolved solids, pH, magnesium, fluoor, sulphate and calcium carbonate) were chosen out of the initial sixteen obtained. The selection that was made was based on the results of a pre-analysis long term trend analysis (for a five year period) of the water quality indicators in each of the three sub-basins. Chosen data sets were compiled to fortnightly and seasonal averages to be used in the analysis phase. The seasons used were determined by combining precipitation and inflow contributions (to the Roodeplaat Dam) for a ten year period. Each of the six chosen water quality indicators were examined in terms of absolute data (fortnightly averages), seasonal averages and long term trends for the fifteen year study period. Time and spatial aspects were integrated to make the sinthesis of the study possible. Albeit some unique conclusions were made, the initial aims of the study could still be reached. It was determined that urban landuse has a more negative influence on the water quality of the Roodeplaat Dam drainage basin than rural landuse (in this case mostly small holdings). Apart from this it was shown that climate (in the form of precipitation) has an even bigger influence on water quality (pollution concentration levels) in the Roodeplaat Dam drainage basin.
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