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.

A Research Report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering University of Witwatersrand Johannesburg, February 2016 / A growing population, rapid urbanisation, and climate change are increasing the pressure on water supplies. The chances of finding new freshwater sources for urban areas are becoming nearly impossible, implying that existing water supplies must go further to satisfy the basic need of potable water. Water reclamation involves the treatment of wastewater to meet defined water quality standards so that it may be reused. Direct potable reuse refers to the introduction of wastewater, which has been treated to meet specified standards, directly into the potable water supply distribution system. Water reuse has become an attractive alternative since wastewater is constantly being produced by populations, which can be treated for reuse. This study examines the sustainability of water reclamation for potable purposes, through an assessment of the Beaufort West Water Reclamation Plant, which includes interviews with the plant manager and process controllers, as well as a review of the relevant documentation. The study employs the use of economic, environmental and societal indicators as a tool in determining the sustainability of water reclamation. The results of the research show that direct potable reuse may be a sustainable solution to reducing the stress on water resources, although certain aspects of the reclamation process require further development in order to progress toward sustainability. In order to provide a long term solution, water reclamation will have to be implemented in conjunction with other water conservation strategies. / MT2017

A research report submitted to the faculty of Commerce, Law and Management, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Management (in the field of Public and Development Management) March 2015 / The citizen science approach has a role to play in the restoration of river health in catchments affected by pollution. Everyone can become involved in monitoring the health of a river, dam, estuary or wetland closest to them. In KwaZulu-Natal, uMngeni and Msunduzi Catchments, voluntary participation in river health initiatives has been adopted by schools, conservancies, NGOs and catchment management forums. The purpose of the study was to explore the perceptions and experiences of the use of miniSASS, a simplified South African Scoring System (SASS) tool for monitoring river health in uMngeni and Msunduzi Catchments over the past 15 years. A qualitative exploratory and descriptive study was undertaken through semi-structured interviews and documentary analysis. The researcher managed to purposively select a sample of ten participants, mainly the active users of the miniSASS citizen science tool in the identified catchments. The finding of the study is that miniSASS is perceived and experienced as a valuable community-based educational tool in Msunduzi and uMngeni catchment which has led to local government authorities to respond faster in solving incidents of industrial pollution; address poorly maintained water infrastructure and fix the leaking sewers contaminating freshwater. The study recommends that a further investigation be made on the economic value of citizen science contribution in KwaZulu-Natal since there were indications that it has already benefited some of the accommodation businesses who appreciated the change in the nearby streams.

MSc., Faculty of Science, University of the Witwatersrand, 2011 / Sodic soils are salt-affected soils which are high in sodium in relation to magnesium and calcium. Commonly called sodic sites in the Kruger National Park (KNP), these patches exhibit unique functional characteristics due to the high levels of sodium which cause surface crusting, cracking and the dispersion of clay particles. The aim of this study is to use satellite imagery to map sodic sites in the KNP at different spatial and spectral scales, giving the best option for a repeatable, semi-automated classification. The resultant map of sodic sites for the KNP will be used as a management tool and for future research projects. A field test for sodicity was necessary to collect sufficient ground truth samples for robust accuracy assessment of the image classification. Sodic soils are identified by measuring EC, pH and SAR which are highly variable within site and between testing methods, and therefore not useful for rapid ground truth classification of sodic soils in the field. The sodium level at which clay particle dispersion takes place varies between soils, but is measurable in the field using the Emerson dispersion test. Laboratory tested sodic soil sites from previous research re-tested in this study showed positive results for dispersion of clay particles in water. The physical properties of sodic sites described in the literature and observed in the field were applied to classify sodic sites in the KNP in the field using a decision tree, together with results from the dispersion test and the observed presence of the grass species Sporobolus iocladus. Landsat 7 and SPOT 5 imagery cover the whole park, with ASTER, CAO hyperspectral, LiDAR and black and white orthophotos available for selected areas. The topography elements of crest and footslope were derived from the STRM 90m digital elevation model (DEM). Image preprocessing to top of atmosphere reflectance was performed where necessary and visual enhancement techniques and transformations were applied to derive the normalised difference vegetation index (NDVI) and other indices. Spectral signatures were checked against spectral signature libraries, and the class separation was tested using the cluster analysis of spectral signatures. MODIS NDVI averages placed the imagery in phenological context. Object-based image analysis using eCognition was applied to classify the sodic sites of the Shingwedzi and Ripape River catchments. The input imagery was segmented into ecologically meaningful patches and classification accuracy was assessed using the field samples collected using the decision tree to identify four classes: sodic sites (bare and woody), river sand, riverine vegetation and savanna areas. Comparison of the accuracy assessments for the Shingwedzi study site showed that the Landsat 7 and SPOT 5 classification algorithms gave an overall kappa index accuracy of 89% and 78% respectively, and a sodic site kappa index of 90% and 89%. Validation results using the ground truth samples gave an overall kappa index accuracy of 61% for Landsat 7 and 52% for SPOT 5, with a sodic site kappa index of 49% and 39% respectively. The classification algorithms were applied to the Ripape study site for Landsat 7 and SPOT 5 with repeatable results for the SPOT 5 imagery of 88% overall kappa index and 81-93% kappa index for sodic sites using similar seasonal imagery in the wet to early dry season. The Landsat 7 classification algorithm was applied to the entire KNP based on the repeatability results of 56% overall kappa index and 60% sodic site kappa index for the Ripape site. The quest for a repeatable algorithm to classify sodic sites from satellite imagery has been met by the SPOT 5 imagery using scenes acquired at similar seasonal stages. The late wet season or early dry season imagery was used to apply the classification algorithm with the best success. Changes in size or shape of sodic sites over time requires very high resolution imagery and further studies to understand where the edge of sodic sites are detected from imagery, and how the phenology of the vegetation growing on these sites affects detecting any change in size of the sodic site.

The main purpose of this study was to assess the negative external impact of water pollution upon water resources and the users thereof within urban areas.

The main purpose of this study was to assess the negative external impact of water pollution upon water resources and the users thereof within urban areas.

The majority of South Africa’s fresh water (lotic and lentic), is eutrophic and this has resulted in water hyacinth, Eichhornia crassipes (C.Mart.) Solms. (Pontederiaceae) becoming South Africa’s most damaging aquatic macrophyte. Recently however, concerns have also been voiced over the presence of highly invasive submerged macrophyte species, such as Eurasian water-milfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River. Interaction studies between floating and submerged macrophytes have shown that floating macrophyte dominance restricts light penetration into the water column shading out submerged macrophytes while submerged macrophyte dominance reduces nutrient availability in the water column limiting floating macrophyte growth. This cycle ensures that these species cannot coexist in the same habitat for extended periods of time. The aims of this thesis were to: 1. Investigate changes in the historical and current macrophyte dominance in the Vaal River 2. Determine whether these changes could be attributed to stochastic events, such as floods and herbicide control measures. 3. The physio-chemical conditions of the water column, and whether pressure from herbivory by macroinvertebrates had possibly influenced Eurasian water-milfoil’s ability to dominate. Spatial and temporal analysis of satellite imagery revealed that water hyacinth and submerged macrophyte species dominated different regions of the study area over different periods of time from 2006 to 2010. This was significantly correlated with nitrate concentrations of the water column. One of the lower Vaal River Water Management Areas (WMA) had changed from a water hyacinth dominated state in 2006 to an alternative submerged macrophyte dominated stable state in 2008. It was concluded that this change could be attributed to: a stochastic flooding event in 2006; perturbation from integrated control measures implemented against water hyacinth; and low nitrate concentrations of the WMA. The lack of any substantial macroinvertebrate herbivory pressure or control measures implemented against Eurasian water-milfoil, compared to similar surveys conducted in the U.S.A. and its native range in Eurasia was shown to contribute to its dominance. Future successful integrated control programmes, including biological control against Eurasian water-milfoil, could provide the perturbation required to restore the ecosystem. However, without the reduction in nitrate concentration levels, water hyacinth will remain the dominant stable state of the rest of the Vaal River.

The prevention of outbreaks of waterborne diseases remains a major challenge to public health service providers globally. One of the major obstacles in this effort is the unavailability of on-line and real-time methods for rapid monitoring of faecal pollution to facilitate early warning of contamination of drinking water. The main objective of this study was to develop a β-glucuronidase (GUD)-based method that could be used for the on-line and real-time monitoring of microbial water quality. GUD is a marker enzyme for the faecal indicator bacteria Escherichia coli. This enzyme breaks down the synthetic substrate p-nitrophenyl-β-D-glucuronide (PNPG) to D-glucuronic acid and p-nitrophenol (PNP), which turns yellow under alkaline pH. The enzymatically produced PNP was used to detect GUD activity. In situ GUD assays were performed using running and stagnant water samples from the Bloukrans River, Grahamstown, South Africa. The physico-chemical properties of environmental GUD were determined, after which a liquid bioprobe and a microbial biosensor modified with Moraxella 1A species for the detection of the enzyme activity were developed. In order to determine the reliability and sensitivity of these methods, regression analyses for each method versus E. coli colony forming units (CFU) were performed. The storage stabilities of the bioprobe and biosensor were also investigated. The physico-chemical properties of in situ GUD were different from those of its commercially available counterpart. The temperature optimum for the former was between 35 and 40 °C while for the latter it was 45 °C. Commercial (reference) GUD had a pH optimum of 8.0 while the environmental counterpart exhibited a broad pH optimum of between pH 5.0 and 8.0. The liquid bioprobe had a limit of detection (LOD) of GUD activity equivalent to 2 CFU/100 ml and a detection time of 24 h. The method was less labour intensive and costly than the culturing method. The liquid bioprobe was stable for at least four weeks at room temperature (20 ± 2 °C). The biosensor was prepared by modifying a glassy carbon electrode with PNP degrading Moraxella 1A cells. The biosensor was 100 times more sensitive and rapid (5-20 min) than the spectrophotometric method (24 h), and was also able to detect GUD activity of viable but non-culturable cells. Thus it was more sensitive than the culturing method. Furthermore, the biosensor was selective and costeffective. The possibility of using a Pseudomonas putida JS444 biosensor was also investigated, but it was not as sensitive and selective as the Moraxella 1A biosensor. The Moraxella biosensor, therefore, offered the best option for on-line and real-time microbial water quality monitoring in South African river waters and drinking water supplies.

Whole Effluent Toxicity (WET) testing has been identified as one of the tools in the management of complex effluents in aquatic ecosystems. In South Africa, toxicity testing has not been required for regulatory purposes. Recently, the Department of Water Affairs and Forestry has adopted WET testing as a tool to evaluate the suitability of hazardous effluent for discharge into receiving environments. This has necessitated suitable procedures to be established for use in the South African situation. With the implementation of the new National Water Act (No 36 of 1998), industries have to comply with set standards to protect the aquatic environment. However, the South African Water Quality Guidelines for Aquatic Ecosystems have been set using international toxicity data, and it is not known if they are comparable with South African conditions. The aim of this study was to investigate the tolerances of selected indigenous riverine invertebrates to complex saline effluents. The study investigated the effects of kraft mill effluent to Tricorythus tinctus, a tricorythid mayfly from the Sabie River, Mpumalanga, and the effects of a textile effluent to baetid mayflies of the Buffalo River, Eastern Cape. Indigenous riverine invertebrates were chosen as test organisms, as there is no toxicity data in South Africa which could be used to evaluate the level of protection afforded by the South African Water Quality Guidelines for Aquatic Ecosystems. The use of indigenous riverine invertebrates added the challenge of variability of a wild population, and the use of a complex effluent as toxicant added the variability of effluent composition. In this study, WET testing was used to determine the dilution of whole effluents required for discharge. Hazard-based guidelines were developed for the disposal of kraft and textile effluents. The level of environmental hazard posed by different effluent concentrations was ranked, and was related to the River Health Class. This indicated effluent concentrations that may be allowed to enter the aquatic environment, e.g. 3% effluent concentration guideline for both general kraft effluent and general textile effluent for the protection of a Class A river. This approach could contribute to the use of an Environmental Risk Assessment, approach for the management of complex effluents. A number of acute 96 hour toxicity tests were conducted following an unreplicated regression design, using kraft and textile effluents as toxicants, mayfly nymphs as test organisms, and river water as diluent and control. Test organisms were sampled from unimpacted, flowing-water riffle areas, and were exposed in recirculating artificial streams (or channels) to a range of effluent concentrations. Mortality was selected as end-point and observed twice daily. The experimental results showed the variability and acute toxicity of both kraft and textile mill effluents. Baetids were more sensitive (mean LC50=16% effluent concentration) to General Textile Effluent (GTE), but less sensitive to Post Irrigation Textile Effluent (PITE). Textile effluent (PITE) held in a holding dam were therefore less variable and less toxic; suggesting that stabilization of the effluent could have contributed to reduced toxicity. Effluent composition, e.g. higher calcium levels, may also have contributed to lowering toxicity. T. tinctus was sensitive to kraft effluents, but showed less variable responses to Irrigation Kraft Effluent than General Kraft Effluent. Toxicity test data indicated that GKE, IKE and GTE should not enter the aquatic environment without treatment, as they can cause adverse effects to aquatic biota. Both kraft and textile effluents must therefore be treated before discharge. Different responses to different effluent batches were probably due to effluent variability. The use of indigenous organisms, and not a standard laboratory organism, could also have contributed to variability. A hazard-based approach could be useful, as it will provide a consistent basis for deciding on the acceptability of impacts, while allowing natural site-specific differences to be taken into account.

Industries producing highly polluted waste waters are having to purify their effluents to meet with ever increasing requirements laid down by water authorities. The South African Water Act of 1956 has prescribed a very high standard to which waste waters must conform before discharge into a South African water course. Enforcement of these standards falls under the jurisdiction of government authorities such as the Department of Water Affairs. Similarly, municipalities and other local authorities set standards with which trade effluents must comply before discharge into public sewers for treatment in a municipal sewage works. These local authorities are empowered to recover from the trader the additional costs incurred in treating trade effluents. Costs are usually levied in respect of volume, oxygen demand, settleable solids and the production of secondary sludge. In recent years, these standards have been enforced to an extent where the survival of several industries has become dependant on whether these industries are able to purify or dispose of their effluents in a manner acceptable to the water authorities. Chap. 1, p. 1.