Academic literature on the topic 'Water quality - South Africa - Roodeplaat Dam'

Abstract A passive sampling device, based on molecularly imprinted membranes (MIM), was fabricated and optimised for sampling polychlorinated biphenyls (PCBs) in aquatic ecosystems. The newly-developed passive sampler was subjected to in-situ calibration studies to determine PCB sampling rates under various conditions of water turbulence and temperature. This was carried out by exposing the passive samplers to water spiked with PCBs in a continuous-flow exposure setup. The samplers were preloaded with known concentrations of performance reference compounds (PRCs) prior to exposure. Sampling rates of seven indicator PCBs' congeners (PCBs 28, 52, 101, 118, 138, 153 and 180) ranged between 15.3 and 95.6 L/d for the different environmental conditions investigated. To determine the field suitability, the samplers were preloaded with PRCs and deployed for 10 days at the Roodeplaat and Hartbeespoort Dams, in South Africa. Water samples were taken at the end of the deployment period to compare the spot-and-grab samples to the developed samplers. PCBs 28, 101 and 138 were detected in the samplers deployed at Hartbeespoort Dam. The samplers deployed at the Roodeplaat Dam had quantifiable amounts of PCBs 28, 52, 101, 138 and 180 (0.047–0.828 ng mL−1 d−1). The sampler enhanced the detectability of PCB 52 and PCB 180, which were not detected in water samples. The field suitability trials indicated that the developed sampler could successfully be used for PCB monitoring. The sampler enhanced the detection of PCBs that would otherwise be too low to detect in samples collected through the traditional spot-and-grab sampling technique.

Abstract This paper discusses raw water quality results for the raw water from Vaalkop dam reservoir in South Africa. A time series analysis was conducted for various parameters over a prolonged period of time. The analysis indicates that apart from conductivity and coliform counts, most parameters were below their recommended threshold levels for the greatest part of the study period.

This paper discusses raw water quality results for the raw water from Bospoort dam in South Africa. A time series analysis was conducted for various parameters over a prolonged period of time. It was revealed that apart from conductivity, hardness, and high coliform counts, most parameters were below their recommended threshold levels for the greatest part of the study period.

A questionnaire survey of over 3 000 recreational users of inland waters in the greater Pretoria and Cape Town areas was conducted during 1987/8 for the purpose of quantifying, as far as possible, the perceptions of the public towards water quality and water pollution in South Africa. Respondents indicated that excessive aquatic plant growth and other visually aesthetic factors were the principal determinants of water quality, regardless of demographic background. These results are comparable to results obtained in similar studies in north America and appear to be indicative of a rising awareness of environmental issues in South Africa. There was a general willingness among respondents to meet the higher costs associated with the achievement of improved standards of water quality and the elimination of the perceived problems enumerated above.

The aim of this study was to assess the potential risk of infection constituted by HAV to persons using surface dam and river water for domestic and recreational purposes. It estimates the potential risk using a deterministic exponential risk assessment model with mean values and conservative assumptions. Hepatitis A virus was detected in 17.5% of river and 14.9% of dam water samples tested. The number of indicator organisms in these sources exceeded drinking and recreational water quality guidelines set by the United States Environmental Protection Agency (US EPA), indicating possible health risks to recreational water users. Based on the available data and taking all the assumptions into consideration, the probability of infection (Pinf) to the higher socio-economic population using the river water for recreational purposes was 1.1 × 10−3 per day and 3.3 × 10−1 per annum if 100 ml was ingested per day. For recreation in the dam water the Pinf value was 1.2 × 10−4 per day and 4.2 × 10−2 per annum. For the lower socio-economic population, risk values for drinking purposes (2 L day−1) were ten-fold greater. These surface waters therefore did not conform to the US EPA guidelines of 1 infection per 10,000 consumers per year for drinking water or eight gastrointestinal illnesses per 1,000 bathers per day in environmental waters used for recreational purposes. This is the first risk assessment study addressing the risk of infection by HAV in surface water to different socio-economic populations in South Africa.

Mafikeng, the capital of the North West Province, receives water from two sources, namely the Molopo eye and the Modimola dam. Once treated, the potable water is mixed and supplied to the city via distribution systems. This study was designed to assess the quality of drinking water in Mafikeng and also to determine whether the water from the two sources has an impact on the mixed water quality. Physico-chemical parameters and bacteriological quality (faecal coliforms (FCs), total coliforms (TCs), heterotrophic bacteria and Peudomonas spp.) was monitored at three drinking water sites weekly for 4 months. The results revealed that the physico-chemical quality of the water was generally acceptable. The pH ranged from 5.7 ± 0.18 to 8.6 ± 0.14, the temperature ranged from 18.3 ± 0.69 to 25.1 ± 0.69 °C and the total dissolved solids (TDS) ranged from 159.9 ± 22.44 to 364.4 ± 12.44 mg/l. These values are within the target water quality range for drinking water as prescribed by WHO, Department of Water Affairs and SANS 241. What is of concern was the microbial quality of the water. FCs, TCs, heterotrophic bacteria and Pseudomonas spp. were present in some of the treated water samples. The most significant finding of this study is that all drinking water samples were positive for Pseudomonas spp. (>100/100 ml).

Detailed source water monitoring showed large variations in the total concentrations of aluminium and iron in the Vaal Dam, South Africa, which were highlighted as a specific concern for one of the largest drinking water treatment plants in South Africa. This study aimed to better understand the presence of these metals in the source water, removal of these metals through the conventional treatment process, and final water quality trends, for the period 2008 to 2014. Aluminium and iron concentrations were highly variable and showed significant influence on colour and turbidity in source water. Sedimentation performed well, and removed over 70% of the metal concentration from the raw water. Filtration removed 15% of the remaining aluminium and iron concentrations. The pH and turbidity of the final water had minor effects on the metal concentration in the final water. The conventional treatment process was shown to be capable of removing aluminium and iron from the source water as both were within water quality limits in the final water. This study highlighted the importance of source water quality monitoring and treatment plant efficacy in evaluating whether the current treatment technology is appropriate for current and future challenges.

Floodplain ecosystems in Africa are under threat due to direct anthropogenic pressure and climate change. The lower Phongolo River and associated floodplain is South Africa’s largest inland floodplain ecosystem and has been regulated by the Pongolapoort Dam since the 1970s. The last controlled flood release from the dam occurred in December 2014, after which a severe drought occurred and only a base flow was released. The central aims of this study were to determine the historic and present water quality state of the middle and lower Phongolo River and assess the possible effects of the most recent drought may have had. Historic water quality data (1970s to present) were obtained from monitoring stations within the Phongolo River catchment to assess the long-term water quality patterns. Using multivariate statistical analyses as well as the Physicochemical Driver Assessment Index (PAI), a water quality index developed for South African riverine ecosystems, various in situ and chemical water variables were analysed. Key findings included that the water quality of the middle and lower Phongolo River has degraded since the 1970s, due to increased salinity and nutrient inputs from surrounding irrigation schemes. The Pongolapoort Dam appears to be trapping nutrient-rich sediments leading to nutrient-depleted water entering the lower Phongolo River. The nutrient levels increase again as the river flows through the downstream floodplain through input from nutrient rich soils and fertilizers. The drought did not have any significant effect on water quality as the PAI remained similar to pre-drought conditions.

Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The study of climate change and its effect on the eutrophication of surface waters is a current and critically important study for the well-being of the entire planet. Within the same emission scenario various probable climate change models outcomes are possible that affect the water quality of a body of water. Voëlvlei is an off-channel dam that supplies water to the city of Cape Town in the Western Cape Province of South Africa. Historically, it is a eutrophic dam and with climate change, its water quality is expected to worsen. Four statistically downscaled climate models are used to produce meteorological outputs that drive the hydrodynamic and water quality model. The times simulated were the present day (1971-1990), the intermediate future (2046-2065) and the distant future (2081-2100). The operating procedure was not expected to change for the dam and inflows and withdrawals were kept the same for each of the simulation periods. The water quality model CE-QUAL-W2 version 3.6 was used. The bathymetry was validated with measured data. The model was calibrated for temperature, phosphorus loading, ammonium, nitrite-nitrates and chlorophyll-a concentration. The model was used to predict a present day situation in the dam, which was the basis from which future changes would be assessed. The main driver for algal growth other than nutrients and light was water temperature, which was linked to air temperature. With climate change, the air temperature will raise and enhance algal growth. The limiting nutrient was phosphorus during the winter and the rest of the year nitrogen limits algal growth. In the present day, the dominant algal group was the green algae. With climate change an increase in the surface water temperature will increase evaporation and cause a decrease in the yield of the dam and further concentrates the algal nutrients. The surface phosphates concentration show increases in all months but especially in autumn. The total algal growth was increased annually and especially during autumn, signalling a seasonal shift and lengthening of the bloom season. The dominant algae however are still the green algae. There will be an increase in the annual concentration of diatoms. The green algae are present in the highest concentrations when compared to diatoms and cyanobacteria. The increase in its nutrients throughout the year as well as the increased water temperature allowed for unabated growth the entire year with peaks earlier in the year during autumn. Cyanobacteria are present at the surface for the entire year at significant concentrations but with intermediate and future climate change their concentrations does not change significantly. The result for cyanobacteria was inconclusive as the inter-variability between the climate models has the greatest variability for cyanobacteria, with 2 models showing an increased concentration and 2 a decreased concentration for intermediate and future time-period. For climate change, the water quality worsens especially during winter. With climate change water quality will worsen earlier in the year confirming a seasonal shift. The modelling of dissolved oxygen proved daunting as the results indicated supersaturation. The concentration of dissolved oxygen does not vary much as would be expected due to the warmer waters.
AFRIKAANSE OPSOMMING: Die studie van klimaatsverandering en die uitwerking daarvan op die eutrofiseering van die oppervlaktewater is 'n huidige en krities belangrike studie vir die welsyn van die hele planeet. Binne dieselfde emissie scenario, is verskeie moontlike uitkomste van klimaat modelle moontlik en die invloed op die kwaliteit van die oppervlakwater. Voëlvlei is 'n buite-bedding dam wat water verskaf aan die stad van Kaapstad in die Westelike Provinsie van Suid-Afrika. Histories is dit is 'n eutrofiese dam en met die verandering van die klimaat sal die kwaliteit van die water na verwagting verswak. Vier statisties afgeskaal klimaat modelle word gebruik om meterologiese toesttande te skep en hiedie word dan gebruik as invoer vir die hidrologiese and water kwaliteits model vir die huidige situasie (1971-1990), die intermediêre toekoms (2046-2065) en die verre toekoms (2081-2100). Die bedruifs-proses vir die dam was nie verwag om te verander nie en die invloei en onttrekkings was dieselfde gehou vir elk van die simulasie periodes. Die watergehalte model CE-QUAL-W2 3.6 was gebruik. Die bathymetrie was bevestig met gemete data. Die model was gekalibreer vir temperatuur, fosfor, ammonium, nitriet-nitrate en chlorofil-a konsentrasie. Die model was gebruik om 'n huidige situasie in die dam te simuleer, wat die basis vir klimaatsveranderinge sou wees. Die vernaamste aandrywer vir die alge groei anders as voedingstowwe en lig, was water temperatuur, wat met lugtemperatuur gekoppel was. Met klimaatsverandering word die lugtemperatuur verhoog en alge groei. Die beperkende voedingstof was fosfor gedurende die winter en die res van die jaar was die dam stikstof beperk. Die dominante alge-groep in die huidige situasie was die groen alge. Met klimaatsverandering stuig die temperatuur van die oppervlakwater, verhoog verdamping, veroorsaak afname in die vlak van die dam en verhoog die konsentrasie van die alge voedingstowwe. Die oppervlak fosfate konsentrasie verhoog in al die maande veral in die herfs. Die totale alge groei jaarliks en veral gedurende die herfs, 'n teken van 'n seisoenale verskuiwing en verlenging van die blom seisoen. Die dominante alge was nog steeds groen alge. Daar sal 'n toename in die jaarlikse konsentrasie van diatome wees. Die groen alge is in die hoogste konsentrasies vergelyk met diatome en sianobakterieë. Die toename in die voedingstowwe deur die loop van die jaar, sowel as die verhoogde watertemperatuur kan vir 'n onverpoos groei vir die hele jaar, veral in die herfs. Sianobakterieë is teenwoordig vir die hele jaar op beduidende konsentrasies, maar met intermediêre en toekomstige klimaat verander die konsentrasies nie veel nie. Die resultaat vir sianobakterieë was onoortuigend as gevolg van die inter-veranderlikheid tussen die klimaats modelle, met 2 modelle wat 'n toename in konsentrasie voorspel en 2 'n afname in konsentrasie voorspel. Vir klimaatsverandering, die kwaliteit van die water vererger veral in die winter. Met klimaatsverandering skyf hierdie verswakking van water kwaliteit na vroeër in die jaar, wat bevestig 'n seisoenale skui vir verergering. Die modellering van opgeloste suurstof was uitdagende en die resultate was super-versadig. Die konsentrasie van opgeloste suurstof wissel nie veel as wat verwag sou word as gevolg van die warmer water.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2005.
A semi-arid country, like South Africa, with unpredictable seasonal rainfall, is subject to great scarcity in water and an ever-increasing demand from the rising human population. Therefore, efficient reservoirs as well as monitoring methods are needed to manage the South African water supply. This study was undertaken on the Eerste River in the Western Cape, South Africa, focusing on the impact of the Klein Plaas dam system on the benthic macroinvertebrates. The study also examined the use of benthic macroinvertebrates as bioindicators of water quality with special reference to the South African Scoring System Version 5(SASS5) that is currently being used nationally. The impoundment of the water, as well as the inter-basin transfer programme and the experimental cage-culture trout farm, all play a significant role in the disturbance impact of the dam on the Eerste River system. The disturbance is manifested as a drop in water quality that can be seen in the distribution of keystone species, changes in the riparian vegetation, as well as in physical-, chemical-, and biomonitoring evaluations. The study also indicated that the SASS5 is effective, but needs some adjustments, such as inclusion of a prediction phase, finer spatial-scale methodologies and greater consideration of the rarity of species.

Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2007.
Small farm dams (< 20 ha) in the Western Cape Province provide adequate water conditions for intensive cage production of rainbow trout (Oncorhynchus mykiss). A major environmental concern of cage aquaculture, however, is the high inputs of nutrients via commercial diets and the subsequent eutrophication of the water source. Eutrophication can result in the degradation of the general water quality (increasing pH levels, oxygen depletion, increased hydrogen sulphide and free ammonia) and shifts in the phytoplankton structure (increased biomass, single species dominance). Deterioration of water quality will affect the success of the fish farming enterprise as well as the performance of irrigation equipment by increasing the risk of clogging and corrosion. Water quality, phytoplankton and zooplankton compositions were monitored at four sites from June 2005 to November 2006 to determine the effects of cage culture on the farm dam environment, its associated biota as well as irrigation water quality. The distribution of nutrients, nitrogen and phosphorus, was mainly influenced by the stratification and mixing regime of the water bodies. Nutrient concentrations increased during the winter mixing period while in the summer months, they seem to settle to the lower part of the water column. Nutrient concentrations of production sites and reference sites were comparable except for the ammonia levels that were significantly higher at the production sites. Phytoplankton corresponded with nutrient availability resulting in high biomass during winter. In terms of biomass, phytoplankton was approximately two times more abundant in production sites compared to reference sites. Assemblage dominance by cyanophytes (Anabaena circinalis, Microcystis spp.) was found more often in production sites, while reference sites were dominated by dinophytes (Ceratium hirundinella, Peridinium spp.). Zooplankton biomass concurred with high phytoplankton biomass in winter. Zooplankton assemblages in production sites sustained much higher biomass. Effects of cage culture on irrigation water quality are evident from increased algal biomass and shifts in species composition. These results indicated that at its present production level, cage culture had impacts on the farm dam environment and irrigation water quality. The most significant evidence was given by increased plankton biomass and single species dominance in production sites. However, these findings can not solely be ascribed to the introduction of aquaculture as various other factors may also contribute to the water quality of these ecosystems.

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.

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)

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)

M.Sc.
The Vaal River is the main source of water supply to the central industrial, mining and metropolitan regions of South Africa, and is, therefore, strictly regulated by small dams and weirs. The Vaal Dam is the main regulator of water to the Vaal River and is of great importance as it supplies water for human consumption and also to the industrial powerhouse of South Africa. Situated at the confluence of its major tributaries, namely the Vaal and Wilge Rivers, and straddling the convergence of the borders of Gauteng, Free State and Mpumalanga provinces, the Vaal Dam is approximately 77 km south of Johannesburg. It is South Africa’s second-largest dam in terms of area, and third-largest in terms of volume, and is a key component in South Africa’s water supply infrastructure. Gauteng, as well as the surrounding provinces are reliant on it for their water supply. Water flow fluctuations are deemed to be important as they could negatively impact upon the water quality. Knowledge of the relationship between fluctuating water flows and water quality is important as strategies can then be devised on this basis to improve the freshwater situation of the country, the associated management systems, and treatment technologies. By establishing the nature of the respective relationships between high water flow and the selected water quality parameters, ways could be found of reducing the costs of water quality problems, such as eutrophication. The various relationships between high water flow and the selected water quality parameters of the Vaal Dam that were established during the course of this study are as follows: In terms of pH, the study found that in the event of a decline in the water flow, the pH value increased and the water body became more alkaline. A decrease in water flow was also found to be associated with an increase in EC. An increase in water flow was found to be associated with a decrease in pH, EC and Chlorophyll-a. An increase in water flow up to a certain level was found to be associated with an increase in nitrates, sulphates and COD.

D. Tech. Chemistry
The increase in industrialisation in South Africa has led to an increase in coal mining and coal utilisation in Mpumalanga. This has resulted in the deterioration in the quality of water upstream of Loskop Dam. Little or no information is available on the occurrence or fractionation of trace metals in sediments, which are reservoirs for pollutants. Furthermore, no information is available concerning the occurrence of polycyclic aromatic hydrocarbons (PAHs), known for their carcinogenic and mutagenic effects, in rivers in the area. The possible impact of leaching of elements and organic compounds from South African coals has not been exhaustively researched. The general objectives of the study were to: 1) assess the impact of potentially toxic metals and organic compounds leaching from coal, on the quality of surface waters via simulated leaching experiments; 2) determine the extent of pollution by trace metals and polycyclic aromatic hydrocarbons of the Olifants, Klein Olifants and Wilge rivers, at selected points in the upper catchment area; and 3) identify and apportion sources of polycyclic aromatic hydrocarbons in the sediment samples from the study area.

The main purpose of this study is to determine the difference in water quality of the rivers between the Katse and Vaal Dams (Wilge River and Vaal Dam reservoir sub-catchments) after the construction of the Lesotho Highlands Water Project. These rivers include the Ash, Liebenbergsvlei and Wilge Rivers. The temporal changes in water constituents, namely: electrical conductivity, chemical oxygen demand, pH, turbidity, ammonia, calcium, manganese and chlorophyll a, at selected water sampling points were analysed to clarify if Katse Dam water has had any impact on the water quality of the Ash, Liebenbergsvlei and Wilge Rivers and the Vaal Dam. The water quality was studied over an eleven-year period from November 1994 until December 2005. This includes a five-year period prior to, and a six-year period following the completion of the Katse Dam. The Ash, Liebenbergsvlei and Wilge Rivers fall within the Wilge sub-catchment, and the Vaal Dam falls within the Vaal Dam reservoir sub-catchment. Both the aforementioned sub-catchments form part of the Vaal River catchment. Physical, chemical and microbiological sampling results were obtained from Rand Water. The results were compared with the in-stream water quality guidelines as set by the Vaal Barrage Catchment Executive Committee. The results of the selected constituents were depicted visually in the form of graphs. Trends in the constituents over the period were then determined. The graphs were divided into two sections namely, pre-Katse Dam (before 1999) and post-Katse Dam (1999 to 2005). Differences in water quality before and after the construction of the Katse Dam were determined from sampling and chemical analysis at six locations, and hence evaluations were made whether the release of Katse Dam water has had a significant effect on the water quality results in the Vaal River System. The water quality results with respect to the different water constituents illustrated a distinct change in water quality over the period. Northwards, towards the Vaal Dam, the difference in water quality became less apparent. Sampling points throughout the study area experienced decreases in: electrical conductivity, chemical oxygen demand, turbidity, ammonia, and manganese. Hence, the release of Katse Dam water into the Vaal River system has had a ii positive influence on the water quality and thus changed the riverine environments in the Vaal River system. The high quality water from the Katse Dam that enters the Vaal River system thus initially increases the quality of the water in the recipient system with a lesser effect downstream. The result is an improvement of water quality in the upper reaches of the Vaal River system and no significant influence on the Vaal Dam itself. However, the change in water quality may have a detrimental effect on the river environment as a result of the increased volume of water entering the system and the resultant soil erosion, which serves for further studies. Consequently, the advantageous high quality water from the Lesotho Highlands is not being optimally utilised, hence the proposed recommendation by Rand Water to alternatively transfer Katse Dam water via a gravity-fed pipeline to the Vaal Dam thereby receiving the full benefit of high quality water, leaving river environments unaltered and possibly lowering purification costs.
Prof. J. T. Harmse Prof. H. J. Annegarn

The major challenge with regular water quality monitoring programmes is making sense of the large and complex physico-chemical data-sets that are generated in a comparatively short period of time. Consequentially, this presents difficulties for water management practitioners who are expected to make informed decisions based on information extracted from the large data-sets. In addition, the nonlinear nature of water quality data-sets often makes it difficult to interpret the spatio-temporal variations. These reasons necessitated the need for effective methods of interpreting water quality results and drawing meaningful conclusions. Hence, this study applied multivariate techniques, namely Cluster Analysis and Principal Component Analysis, to interpret eight-year (2005–2012) water quality data that was generated from a monitoring exercise at six stations in uMngeni Basin, South Africa. The principal components extracted with eigenvalues of greater than 1 were interpreted while considering the pollution issues in the basin. These extracted components explain 67–76% of the water quality variation among the stations. The derived significant parameters suggest that uMngeni Basin was mainly affected by the catchment’s geological processes, surface runoff, domestic sewage effluent, seasonal variation and agricultural waste. Cluster Analysis grouped the sampling six stations into two clusters namely heavy (B) or low (A), based on the degree of pollution. Cluster A mainly consists of water sampling stations that were located in the outflow of the dam (NDO, IDO, MDO and NDI) and its water can be described as of fairly good quality due to dam retention and attenuation effects. Cluster B mainly consist of dam inflow water sampling stations (MDI and IDI), which can be described as polluted if compared to cluster A. The poor quality water observed at Cluster B sampling stations could be attributed to natural and anthropogenic activities through point source and runoff. The findings could assist in determining an appropriate set of water quality parameters that would indicate variation of water quality in the basin, with minimum loss of information. It is, therefore, recommended that this approach be used to assist decision-makers regarding strategies for minimising catchment pollution.