Thesis (M. Sc. (Geography))--Rhodes University, 2006.

A conceptual end use model for residential water demand and return flow is presented in this thesis. The model requires a unique description of a single residential stand in terms of all its end-uses. The end-uses include toilet flushing, bathing and showering, garden watering, leaks, et cetera. Various parameters describe each of the end-uses. The model predicts five components relating to water demand and wastewater flow at a residence: indoor water demand, outdoor water demand, hot water demand, wastewater flow volume and concentration of solutes in the wastewater. Twelve monthly results are calculated, for each of the five components, to provide a typical seasonal pattern as well as an annual value. The large number of input parameters in an end-use model allows for powerful and detailed analysis. The parameters required to populate the model are discussed and guideline values are presented. The end-use model is used to conduct a sensitivity analysis of each independent parameter for each of the five individual model components. The elasticity and sensitivity is determined at a base point with respect to each parameter for all five results. A research significance index is also devised to integrate the elasticity and availability of data for each parameter. The result is a prioritised list of the most critical parameters for each of the five components, which are the ones that should receive the focus for future study and data recording. The parameters are combined to obtain a list of the overall most important parameters in the model for all components combined, and based on a combination of the elasticity-based rank and the sensitivity based rank. The five most important parameters are the household size, toilet flush frequency, toilet flush volume, the washing machine event frequency and the volume of leaks on a stand. The practical application of the model is illustrated. The researchers first apply the model to mimic a few commonly accepted characteristics of water demand. The effectiveness of some specific water demand management measures are evaluated by adjusting selected model parameters. The measures include xeriscaping, the installation of dual-flush toilets, low-flow showerheads, pool ownership and pool cover use. The model also enables practitioners to obtain an insight into the water use habits of homeowners. The model forms the basis for further research work in the field. Its relatively simple structure and realistic data requirement encourages its integration into existing commercially available software suites for water and sewer system analysis and -management in the civil engineering industry in South Africa, as well as abroad. / Prof. J. Haarhoff

The work presented in this thesis stemmed out of the apparent lack of a method for incorporating salinity effects into environmental life cycle assessments. Salination of the water resources is a well-known problem in South Africa, and is of strategic concern. Any environmental decision support. tool that does not allow the evaluation of salinity effects therefore has limited applicability in the South African context. The starting-point for the work presented in this thesis was to evaluate existing impact categories, and the characterisation models used to calculate equivalency factors for these impact categories, in an attempt to incorporate salinity effects into existing categories and/or characterisation models. The types of effects that elevated (above normal background levels) dissolved salt concentrations have on the natural and man-made environment were evaluated, and it was concluded that, although there was some overlap with existing impact categories, some of the salinity effects could not be described by existing impact categories. It was also concluded that there are clear and quantifiable causal relationships between releases to the environment and salinity effects. A separate salinity impact category was therefore recommended that includes all salinity effects, including; aquatic ecotoxicity effects, damage to man-made environment, loss of agricultural production (livestock and crops), aesthetic effects and effects to terrestrial fauna and flora. Damage to the man-made environment is evaluated in terms of effects on equipment and structures, interference with processes, product quality and complexity of waste treatment, and is used as an indicator for the environmental consequences derived from the caused additional activity in the man-made environment. Once a conceptual model for a separate salinity impact category had been formulated, existing characterisation models were evaluated to determine their applicability for modelling salinity effects. Salination is a global problem, but generally restricted to local or regional areas, and in order to characterise salinity effects, an environmental fate model would be required in order to estimate salt concentrations in the various compartments, particularly surface and subsurface water. A well-known environmental fate and effect model was evaluated to determine if it could be used either as is, or in modified form to calculate salinity potentiaIs for LCA. It was however concluded that the model is not suitable for the calculation of salinity potentials, and it was therefore decided to develop an environmental fate model that would overcome the limitations of existing model, in terms of modelling the movement of salts in the environment. In terms of spatial differentiation, the same approach that was adopted in the existing model was adopted in developing an environmental fate model for South African conditions. This was done by defining a aunit South African catchmenta (including the air volume above the catchment), which consists of an urban surface; rural agricultural soil (and associated soil moisture); rural natural soil (and associated moisture), groundwater (natural and agricultural) and one river with a flow equal to the sum of the flows of all rivers in South Africa, and a concentration equal to the average concentration of each river in the country. A non steady-state environmental fate model (or, hydrosalinity model) was developed that can predict environmental concentrations at a daily time-step in all the compartments relevant to the calculation of salinity potentials. The environmental fate model includes all the major processes governing the distribution of common ions (sodium, calcium, magnesium, sulphate, chloride and bicarbonate) in the various compartments, and described as total dissolved salts. The effect factors used in the characterisation model were based on the target water quality ranges given by the South African Water Quality Guidelines in order to calculate salinity potentials. The total salinity potential is made up of a number of salinity effects potentials, including; damage to man-made environment, aquatic ecotoxicity effects, damage to man-made environment, loss of agricultural production (livestock and crops), aesthetic effects and effects to terrestrial fauna and flora. The total salinity potentials for emissions into the various initial release compartments are shown in the table below. Initial release compartment Atmosphere River Rural natural surface Rural agricultural surface Total salinity potential (kg TDS equJkg) 0.013 0.16 0.03 1.00 The salinity potentiaIs are only relevant to South African conditions, and their use in LeA in other countries may not be applicable. This, in effect, means that the life cycle activities that generate salts should be within the borders of South Africa. It has been recognised that the LCA methodology requires greater spatial differentiation. Salination is a global problem, but generally restricted to local or regional areas on the globe, and it is foreseen that local or regional salinity potentials would need to be calculated for different areas of the earth where salinity is a problem. The LCA practitioner would then need to know something about the spatial distribution of LCA activities in order to apply the relevant salinity potentials. The LCA practitioner should also take care when applying the salinity potentials to prevent double accounting for certain impacts. Currently, this is simple because no equivalency factors exist for common ions, or for total dissolved salts as a lumped parameter. The distribution of salinity potentials, which make up the total salinity potential, appears to be supported by the environmental policies and legislation of South Africa, in which irrigation using saline water is listed as a controlled activity, and subject to certain conditions. The major recommendations regarding further work are focussed on the collection of data that will allow further refinement of the model, and to decrease the uncertainty and variability associated with the results. The values of the published equivalency factors are dependent on the mathematical definition of the local or regional environment, and these values have been calculated for Westem European conditions. Equivalency factors may vary by several orders of magnitude, depending on how the local or regional conditions have been defined. It is therefore recommended that the model developed in this work ultimately be included into a global nested model that can be used to calculate equivalency factors for other compounds, including heavy metals and organic compounds. This would result in equivalency factors for all compounds that are relevant to South Africa. / Thesis (Ph.D.)-University of Natal, Durban, 2003.

Thesis (MScEng (Civil Engineering))--Stellenbosch University, 2008. / In recent years, concern about the water quality in the Berg River received a fair degree of attention, particularly with the imminent construction of the Berg Water Project (BWP). Particular concerns have been expressed about the water quality with respect to total dissolved salts (TDS) at Misverstand Dam. In previous studies (Fourie and Görgens, 1977) it was identified that the saline water was mostly generated in the lower portion of the Berg River Catchment (Matjies, Moorreesburg and Sandspruit Rivers) and that the abstraction of acceptable quality water higher up in the Berg River could possibly result in salinity problems at Misverstand Dam. Contrary to expectation, these studies also showed that for the most saline catchments, a winter peak in TDS concentrations also existed. To help address these concerns, a Water Research Commission (WRC) project was initiated in 2003 in which the newly-developed salinity module of the daily Agricultural Catchment Research Unit (ACRU) agrohydrological model, known as ACRUSalinity, would be configured for the Berg River Catchment. This model had previously been configured and calibrated for the Mkhomazi Catchment (Teweldebrhan, 2003) which exhibited relatively low streamflow TDS concentrations (100 mg/l) and it was deemed necessary to ascertain whether comparable TDS values could be simulated in the Berg River Catchment, where TDS concentration could rise to well above 1 000 mg/l in certain tributaries. In this project, ACRUSalinity was configured for the Berg River Catchment on a distributed basis, aiming to capture the spatial distribution of rainfall and geophysical characteristics which inherently exist in a catchment as expansive as the Berg. Initial application of the "Beta version" of ACRUSalinity to the Berg River Catchment revealed that it failed to produce simulated TDS values which were representative of the observed data. It became evident that the model required both additional salinity-related functions and modifications of existing functions. After the implementation of these algorithm changes the correspondence of simulated and observed TDS concentrations improved markedly. Verification of the ACRUSalinity simulated flows and calibration of the salinity-related parameters was based on the values of predefined objective functions. Reasonably representative flows could be obtained provided that the catchment discretisation and driver rainfall selection process were adequate. Salinity related parameters were determined purely on an iterative basis, although a priori estimation of these parameters was possible. Preliminary interdependency tests of these parameters revealed that the final calibrated set of salinity-related parameters was probably not unique and that some a priori decision making would be required when selecting the most realistic set of parameters. Quantification of the potential effect of the Berg River Dam on the TDS concentrations at Misverstand Dam was achieved as follows: the ACRUSalinity model was verified for flow and calibrated for TDS at available and reliable flow gauging stations. This was then followed by a long-term simulation run which yielded daily TDS time series for comparison, on an exceedance basis, with the observed record. Since the concern about the possible deterioration of water quality at Misverstand Dam was only a winter concern (May to September), comparisons were only drawn over this period. The flow-routing option in ACRUSalinity was not activated and a 1:1 daily comparison of flows and TDS concentrations, based on values of the objective function, was thus not possible. Results from this study showed that even with a daily model, the exceedance percentages of the TDS concentrations after the construction of the Berg River Dam were comparable with the exceedance percentages obtained from the original monthly modelling study (DWAF, 1993). In this study, however, it was possible to capture the increasing TDS concentration which was evident over winter months in the observed data record for the Matjies River and Sandspruit River catchments. The testing of the model’s effectiveness in the evaluation of engineering options was accomplished as follows: several options for ameliorating the possible deterioration of water quality at Misverstand Dam were defined, based on its practicality and cost of implementation. For example, the Withoogte water treatment works abstracts water from Misverstand Dam for supply to the West Coast region when water quality is acceptable (i.e. a TDS lower than 450 mg/l). It was proposed that to minimise the effect of periods when no abstraction from Misverstand could occur due to unacceptable water quality, a second reservoir at the treatment works should be lined and used to provide bridging storage for water from Misverstand Dam when the water quality was acceptable. The calibrated ACRUSalinity model was then modified to reflect the physical attributes of this engineering scenario of interest to produce sets of flow and TDS time series which could be further analysed to determine assurance of supply, in terms of predetermined TDS concentration thresholds in Misverstand Dam. Using this particular engineering option, the analysis revealed that a 300 mg/l TDS upper-limit at Misverstand was too stringent and that 450 mg/l was probably more realistic.

"January 14, 2004" Includes bibliographical references (leaves 201-213)

The movement of a fluid and solute through a porous medium is of great practical interest because this describes the spread of contaminants through an aquifer. Many contaminants occur at concentrations sufficient to alter the density of the fluid, in which case the physics is typically modelled mathematically by a pair of coupled, nonlinear partial differential equations. There is disagreement as to the exact form of these governing equations. Codes aiming to solve some version of the governing equations are typically tested against the Henry and Elder benchmark problems. Neither benchmark has an analytic solution, so in practice they are treated as exercises in inter code comparison. Different code developers define the boundary conditions of the Henry problem differently, and the Elder problems results are poorly understood. The Henry, Elder and some other problems are simulated on several different codes, which produce widely-varying results. The existing benchmarks are unable to distinguish which code, if any, simulates the problems correctly, illustrating the benchmarks' limitations. To determine whether these discrepancies might be due to numerical error, one popular code, SUTRA, is considered in detail. A numerical analysis of a special case reveals that SUTRA is numerically dispersive. This is confirmed using the Gauss pulse test, a benchmark that does have an analytic solution. To further explain inter code discrepancies, a testcode is developed which allows a choice of numerical methods. Some of the methods are based on SUTRA's while others are finite difference methods of varying levels of accuracy. Simulations of the Elder problem reveal that the benchmark is extremely sensitive to the choice of solution method: qualitative differences are seen in the flow patterns. Finally, the impact of numerical error on a real-world application, the simulation of saline disposals, is considered. Saline disposal basins are used to store saline water away from rivers and agricultural land in parts of Australia. Existing models of disposal basins are assessed in terms of their resemblance to real fieldsite conditions, and in terms of numerical error. This leads to the development of a new model which aims to combine verisimilitude with numerical accuracy. / Thesis (Ph.D.)--School of Mathematical Sciences (Applied Mathematics), 2004.

Discourses on challenges regarding water access in South Africa municipalities are intertwined with the concept of human rights and sustainable development goals. Stakeholders and social scientists continue to debate the plaque of service delivery in regard to water access in the African continent. These debates are framed around discussions to explore suitable governance models that are proficient to promote, protect and rule the right to water access amongst the poor. If South Africa and global curve continue to ignore the pleas of the disadvantaged communities on lack of water access, water scarcity will increase causing droughts and floods. The study investigated the water access, challenges and coping strategies in informal settlements specifically focusing on Iscor informal settlement. The challenges of access to water and coping strategies in informal settlements is a continuous issue of concern in South Africa Municipalities. The study was premised on qualitative approach and employed both the snowball sampling and purposive sampling techniques which refer to key participants in the study area, the government officials and the key individuals interviewed for the research. Data were gathered from a total of 61 participants; interviews were conducted with 20 participants in the study area, 10male focus group and 10 female focus group participants, three key individuals from the study area, three government officials from Department of Water and Sanitation (National and Provincial office), five officials from the City of Tshwane metropolitan Municipality and lastly 10 residents on the impact of research, since the collaboration of the research resulted in the provision of basic amenities to the study area during the course of the research. The study analyses the findings of the stated case studies, with each narrative capturing the themes on Demography; Historical background of the study area; level and impact of water access and coping strategies. The findings from the study reflected the complex range of factors influencing and exacerbating the household resilience to water inaccessibility. The research recommends that the government should implement monitoring programmes and projects which will ensure water accessibility in all informal settlements across the city, provide shelters/RDP houses to the residents, educate and create jobs through support groups and NGOs to the study area. / Development Studies / M.A. Development Studies

Thesis (M.Sc.)--University of Adelaide, Dept. of Geology and Geophysics, 2003. / Includes bibliographical references (leaves 112-115).

South Africa is an arid country and its growing population is putting freshwater resources under increasing pressure. Natural salinization of freshwater systems is being exacerbated by anthropogenic influences. The National Water Act (No. 36 of 1998) stipulates the need for an ecological Reserve, that quantity and quality of freshwater needed to protect freshwater ecosystems while allowing sustainable use of freshwater resources. Water guidelines do exist in the form of the South African Water Quality Guidelines (DWAF, 1996) and more recently, Jooste and Rossouw (2002) compiled benchmark values for water quality variables marking the boundaries between ecological health classes in the 4-category classification system. Predominantly international toxicity data were used to compile the guidelines and the benchmark values. In addition, there is a paucity of chronic toxicity data nationally and internationally. This thesis showed that it is statistically possible to derive protective chronic endpoints for salinity from acute toxicity data through extrapolation. The Acute to Chronic Ratio (ACR), Two-Step Linear Regression (LRA) and Multi-Factor Probit Analysis (MPA) extrapolation methods were investigated to derive chronic toxicity data from acute toxicity data. The authors of LRA and MPA recommend associating a time independent LCx value in the range of LC₀¸₀₁ to LC₁₀ with a Predicted No Effect Concentration (PNOEC). In addition to published methods, this thesis studied the possibility of equating a time independent LC₅₀ value and subjected to a safety factor of 5 (LRA LC₅₀/5), to the PNOEC. Extrapolated chronic toxicity data where the toxicants are NaCl and Na₂SO₄ were derived for indigenous South African macroinvertebrates. NaCl and Na₂SO₄ are salts associated with salinisation in South Africa. In addition, a chronic salinity toxicity test protocol for an indigenous South African aquatic macroinvertebrate was designed and chronic toxicity test were performed using NaCl and Na₂SO₄ as toxicants. The experimental chronic toxicity data produced were used to validate results from the acute to chronic extrapolation methods. Extrapolated chronic toxicity data were inputted into Species Sensitivity Distribution curves, and concentrations that were predicted to protect 95 % of species (PC95) were compared to the sub-lethality benchmarks proposed by Jooste and Rossouw (2002) for NaCl and Na₂SO₄. This study concluded that the LRA LC₅₀/5 extrapolation method is the most protective and accurate and proposed that LRA replace the ACR method in future guideline development for inorganic salts.

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