M.Sc. (Environmental Management) / The main purpose of this study is to determine whether trends in rainfall patterns correlate to trends in water quality constituents for the Roodeplaat Dam Drainage Basin, thereby increasing the ‘dilution capacity’ potential of the aforementioned water system. The Roodeplaat Dam (reservoir) is a hypertrophic impoundment located approximately 20 kilometres north-east of Pretoria. The dam was originally designed for irrigational purposes and later became an important recreational site. In recent years it serves as an important source for Magalies Water, which represents a state-owned water board that currently supplies potable water to a large area north of Pretoria. The Roodeplaat Dam catchment consists of three contributing rivers to the inflow of the impoundment, namely: The Pienaars River (located in the centre of the catchment), the Edendale Spruit (east of the catchment) and the Moreleta/Hartebees Spruit (west of the catchment). There are also two Water Care Works (Zeekoegat and Baviaanspoort) within the catchment, which supplement additional inputs of treated effluent discharges to the reservoir. Temporal changes in selected physical, chemical and microbial constituents were analysed at established sampling points along each river, including a sample site located at the dam wall outlet. Such changes in water quality, in conjunction with rainfall patterns exhibited in the study area were analysed to determine whether an association exists between the two variables, and more specifically how rainfall impacts on water quality within the catchment which has a direct effect on the quality of the Roodeplaat Dam. Data for rainfall and water quality were analysed over a 10 year period, from January 1999 to December 2009. Water quality sampling results were obtained from the Department of Water Affairs. Rainfall data for the same time period in question was obtained from the South African Weather Service. Results for both variables were projected graphically and collated to determine whether rainfall trends have an impact on concentrations of water quality constituents. Constituent concentrations were also compared at each sample site. To quantitatively justify graphical results, the author preformed Pearson’s and Spearman’s correlation analysis to establish whether rainfall and water quality concentrations displayed significant associations. Results from graphical presentations and quantitative analyses identified that a correlation does exist between rainfall and water quality constituents, whereby an increase in rainfall tends to result in a decrease of water quality constituent concentrations. Microbial constituents contrasted to physical and chemical results, and displayed a strong positive correlation to rainfall. Rainfall therefore increases the ‘dilution capacity’ potential of the catchment, whereby the water system increases in its ability to receive and remove pollutants disposed in them by human induced land-use activities. It was also found from the study that the strength and association between rainfall and water quality constituents is affected by external, anthropogenic variables which also exert an influence on the quality of water present in the Roodeplaat Catchment Area. This includes additional inputs from the Baviaanspoort, which is located along the Pienaars River. Results from the sample site located on this river displayed no relationship for many of the water quality constituents tested. It has also been highlighted from the study how the landscape has been severely altered by the rapid rate of human induced land use activities in the past decade. Further investigations need to incorporate the influences of natural phenomena, such as rainfall, together with influences exerted from anthropogenic activities. This will provide clearer information on the interdependent factors at play which compromise the dilution capacity potential of the Roodeplaat Catchment Area and subsequently the poor water quality status exhibited at the impoundment. Once such externalities are accounted for, it is recommended that a suitable management plan be conducted for the Roodeplaat Catchment Area that is based on scientific grounding and proactively mitigates the impacts exuded by land-use activities, thereby improving the status of the Roodeplaat impoundment.

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.

M.Sc. / A comprehensive histology-based fish health assessment was implemented at the Roodeplaat Dam (RD), Pretoria, South Africa, to determine the health status of two fresh water fish species, Clarias gariepinus (n = 20) and Oreochromis mossambicus (n = 18), after exposure to pollutants. RD is known to be polluted, being impacted from two sewage treatment plants, industry, housing and agriculture all upstream of the reserve. Excessive nutrient loads, such as orthophosphate, resulted in the dam becoming eutrophic. The quality of water in the RD was a cause for concern, as the fish from the dam are being used as a source of food by the local people. The histology-based fish health assessment included fish necropsy, calculation of gross body indices and histological assessment. Water quality (chemical and physical) analysis was also carried. Furthermore, target chemical analysis of fish tissue (skeletal muscle) was performed to determine the levels of contaminants in the consumable parts of the fish. These results were compared with existing international guidelines to determine whether the harvested fish were safe for human consumption. All the information obtained was integrated in a qualitative and quantitative scenario-based health risk assessment.

Eutrophication is a nutrient enrichment of dams and lakes. Increased eutrophication in dams results in blooms of cyanobacteria. Cyanobacteria are troublesome as they form massive surface scums, impart taste and odour to the water. Some strains of cyanobacteria such as Microcystis aeruginosa are dangerous to humans and animals. They produce toxins that can kill animals drinking the contaminated water and have also been implicated in human illnesses. The study investigated the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei, Roodeplaat and Hartbeespoort Dams. This was done by interpreting data from April 2010 to March 2012. The conditions in the three dams show that Microcystis produced toxins in the summer season and all the variables analysed were favourable for the production of toxins. The methods deployed to rehabilitate the dams do not completely solve the problems of toxins experienced by the dams. / Environmental Sciences / M. Sc. (Environmental Management)

Eutrophication is a nutrient enrichment of dams and lakes. Increased eutrophication in dams results in blooms of cyanobacteria. Cyanobacteria are troublesome as they form massive surface scums, impart taste and odour to the water. Some strains of cyanobacteria such as Microcystis aeruginosa are dangerous to humans and animals. They produce toxins that can kill animals drinking the contaminated water and have also been implicated in human illnesses. The study investigated the effectiveness of techniques deployed in controlling cyanobacterial growth in Rietvlei, Roodeplaat and Hartbeespoort Dams. This was done by interpreting data from April 2010 to March 2012. The conditions in the three dams show that Microcystis produced toxins in the summer season and all the variables analysed were favourable for the production of toxins. The methods deployed to rehabilitate the dams do not completely solve the problems of toxins experienced by the dams. / Environmental Sciences / M. Sc. (Environmental Management)

Freshwater resources and supplies in South Africa are experiencing severe stress from rising population growth, drought and high urbanization. The stress factors have also exerted pressure on wastewater treatment works leading to the release of partially treated effluent. The study assessed and compared the impact of the two wastewater treatment works effluent discharged into the Roodeplaat Dam. Selected physical parameters (pH, conductivity), chemical parameters (total oxidised nitrogen, phosphate, chemical oxygen demand, chloride, sulphate, sodium) and microbiological parameter (Escherichia coli) were evaluated and compared with South African standards. Secondary data (from January 2012 to December 2017) was used to identify parameters that were above or below regulatory standards. The t-test (p < 0.05) was used to compare changes between 2012 and 2018 over the same months.The results indicated that aquatic ecosystem quality has not improved, degradation continues as well as a lack of intervention from authorities. The leading parameters in causing stress to Roodeplaat water quality in descending order were Escherichia coli (E. coli), Phosphate (PO43-), Total Oxidized Nitrogen (TON), Chemical Oxygen Demand (COD), Chlorophyll a (Chl a), Ammonia (NH3), Electrical Conductivity (EC) and Sodium (Na). One of the main reasons why poor effluent was released is limited financial investment to upgrade the treatment facilities. This research provided highlights on the need to enforce extra measures to guarantee compliance of treated effluent quality to the existing guidelines. Moreover it highlights the need for concerned department’s authorities to invest in water by allocating enough budget to address the challenge of wastewater treatment works upgrades. / Environmental Sciences / M. Sc. (Environmental Sciences)