The erosion of headwater wetlands in the Sand River catchment, in the lowveld of north-eastern South Africa has led to a focus on their rehabilitation, both for livelihood security for those that use them for subsistence agriculture, as well as for provision of streamflow regulation services for the Sand River itself. One such wetland, the Craigieburn-Manalana itself undergoing severe erosion was subject to technical rehabilitation using concrete weirs and gabion dams to stabilize the erosion gullies during 2007. Through a series of papers the research discussed in this thesis examined the response of the wetland?s hydrodynamics to the implementation of these measures. Through the installation of a network of hydrometric apparatus the research has shown that the wetlands hydrology is largely controlled by the presence of both horizontal and vertical clay aquicludes within a hydraulically conductive sandy matrix. The sequence of these aquicludes had allowed for artesian phreatic surface phenomena identified in a relatively hydrologically intact region of the wetland. The gully erosion had initiated hydraulic drawdown of the wetland?s water table leading to the desiccation of the system. The construction of a buttress weir within the erosion gully had restored the wetlands hydrodynamics to that typical of conditions upstream of a clay-plug. The research also explored the role that clay plays in terms of controlling the wetland?s hydro-geomorphic setting through geophysical analysis. A conceptual model was then derived that states that these wetlands are held in place by clay-plugs that form through clay illuviation from the hillslopes at regions of valley confinement. This has important implications for the connectivity of wetland process domains. The research also determined the inputs of surface and subsurface flows to the wetland and it was found through detailed examination of soil moisture responses and variably saturated soil physics modelling using the HYDRUS model, that the wetland is hydrologically connected to its contributing hillslope by threshold induced preferential flow pathways, via macropores, that only respond after specific antecedent soil moisture conditions are met. In addition, the thesis describes novel approaches to use information provided by soil scientists for the development of catchment hydrological models. It was shown that the use of this hydropedology information improved the low flow response function of the catchment model, ACRU. This development has important implications for up-scaling of catchment process domains, or hydrological response units by being able to generalize on hillslope hydrological responses based on configuration of their soil type elements. The research also undertook to examine the role that the wetlands play in catchment processes. It was found through water budgeting, supported by hydrological time-series, stable isotope analysis and the quantification of vegetation water use within the wetland and contributing catchment, that these wetlands do not augment baseflows during the dry season. Furthermore, it is only early on during the wet season that these systems may attenuate peak flows, thereafter they act as conduits for high storm flows. Similarities emanated from this research with previous hydrological studies of headwater wetland systems in southern Africa and these are discussed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

No description available.

No description available.

One seldom comes across felicitous love in nineteenth-century French literature. Viewed in an unfavourable light, being looked upon as sheer utopianism, felicitous love never quite made it as a major theme in fiction. But idealized as it is in the works of George Sand, this particular topic never ceases to be true to life: the "weltanschauung" in which it originates is far too focused on the realm of reality for love to be put through senseless poetising. To highlight this singularity, this essay focuses on the love symbolic in three George Sand's novels, Indiana (1832), Le Meunier d'Angibault (1845), and Le Marquis de Villemer (1860), by going into the heroine's quest for the ideal. Contemplated with the romantic presupposition (that of the self versus society), this particular quest is subjected to a plural approach (ideological, chronotopical, initiatory) likely to fathom out a symbolic inherent to a writer known after all as "la romanciere de l'amour".

Liquefaction of sandy soil has been observed to cause significant damage to infrastructure during major earthquakes. Historical cases of liquefaction have typically occurred in sands containing some portion of fines particles, which are defined as 75μm or smaller in diameter. The effects of fines on the undrained behaviour of sand are not however fully understood, and this study therefore attempts to quantify these effects through the undrained testing of sand mixed with non-plastic fines sourced from Christchurch, New Zealand. The experimental program carried out during this study consisted of undrained monotonic and cyclic triaxial tests performed on three different mixtures of sand and fines: the Fitzgerald Bridge mixture (FBM), and two Pinnacles Sand mixtures (PSM1 and PSM2). The fines content of each host sand was systematically varied up to a maximum of 30%, with all test specimens being reconstituted using moist tamping deposition. The undrained test results from the FBM soils were interpreted using a range of different measures of initial state. When using void ratio and relative density, the addition of fines to the FBM sand caused more contractive behaviour for both monotonic and cyclic loadings. This resulted in lower strengths at the steady state of deformation, and lower liquefaction resistances. When the intergranular void ratio was used for the interpretation, the effect of additional fines was to cause less contractive response in the sand. The state parameter and state index were also used to interpret the undrained cyclic test results – these measures suggested that additional fines caused less contractive sand behaviour, the opposite to that observed when using the void ratio. This highlighted the dependency on the parameter chosen as a basis for the response comparison when determining the effects of fines, and pointed out a need to identify a measure that normalizes such effects. Based on the FBM undrained test results and interpretations, the equivalent granular void ratio, e*, was identified from the literature as a measure of initial state that normalizes the effects of fines on the undrained behaviour of sand up to a fines content of 30%. This is done through a parameter within the e* definition termed the fines influence factor, b, which quantifies the effects of fines from a value of zero (no effect) to one (same effect as sand particles). The value of b was also determined to be different when interpreting the steady state lines (bSSL) and cyclic resistance curves (bCR) respectively for a given mixture of sand and fines. The steady state lines and cyclic resistance curves of the FBM soils and a number of other sand-fines mixtures sourced from the literature were subsequently interpreted using the equivalent granular void ratio concept, with bSSL and bCR values being back-calculated from the respective test data sets. Based on these interpretations, it was concluded that e* was conceptually a useful parameter for characterizing and quantifying the effects of fines on the undrained behaviour of sand, assuming the fines influence factor value could be derived. To allow prediction of the fines influence factor values, bSSL and bCR were correlated with material and depositional properties of the presented sand-fines mixtures. It was found that as the size of the fines particles relative to the sand particles became smaller, the values of bSSL and bCR reduced, indicating lower effect of fines. The same trend was also observed as the angularity of the sand particles increased. The depositional method was found to influence the value of bCR, due to the sensitivity of cyclic loading to initial soil fabric. This led to bSSL being used as a reference for the effect of fines, with specimens prepared by moist tamping having bCR > bSSL, and specimens prepared by slurry deposition having bCR < bSSL. Finally the correlations of the fines influence factor values with material and depositional properties were used to define the simplified estimation method – a procedure capable of predicting the approximate steady state lines and cyclic resistance curves of a sand as the non-plastic fines content is increased up to 30%. The method was critically reviewed based on the undrained test results of the PSM1 and PSM2 soils. This review suggested the method could accurately predict undrained response curves as the fines content was raised, based on the PSM1 test results. It also however identified some key issues with the method, such as the inability to accurately predict the responses of highly non-uniform soils, a lack of consideration for the entire particle size distribution of a soil, and the fact the errors in the prediction of bSSL carry through into the prediction of bCR. Lastly some areas of further investigation relating to the method were highlighted, including the need to verify the method through testing of sandy soils sourced from outside the Christchurch area, and the need to correlate the value of bCR with additional soil fabrics / depositional methods.

Silica is a common silicon dioxide (SiO2) that can be crystalline or non-crystalline (amorphous). Amorphous silica is considered to be less hazardous than crystalline silica. Three dominant crystalline polymorphs exist, with silica quartz being the most common. Exposure to respirable crystalline silica (quartz) causes silicosis, a lung scarring disease. The aim of this study was to identify and quantify the silica exposure in respirable dust personal exposure samples, as well as in representative bulk samples which are large samples taken from the sources of airborne dust obtained from different mining and production plants involved in the production of titanium dioxide from beach sand. This is needed to determine the degree of risk of developing silicosis. Forty five workers employed in different mining and production plants participated in this study. Their eight-hour personal exposure to respirable particulate was determined. Personal respirable dust exposure samples and bulk samples were analyzed for silica by an accredited laboratory by means of X-ray diffraction based on NIOSH method 7500. Silica quartz was detected in personal respirable dust samples and bulk dust samples obtained from the mining and production plants, but amorphous silica was only detected in three personal exposure samples at the Slag plant and in the bulk sample obtained from the Roaster plant. All the silica quartz and amorphous silica concentrations in personal exposure samples were well below their respective exposure limits of 0.1 mg/m3 (quartz) and 3 mg/m3 (amorphous). No significant differences were found between the silica quartz concentrations in personal respirable exposure samples obtained from the mining ponds and the production plants, although a practical significance was found between some mining and production area personal exposure samples. The non-significant differences found between exposure concentrations and a practical significance suggest the necessity of involving a larger sample group in future. Other studies done in non-mining industries showed that some workers were over exposed to respirable silica dust. Compared to these findings the results of the present study showed the opposite, with respirable silica dust levels being below the South African action level and OEL. Further research, involving more samples, spread over a longer period of time, would probably be able to show a clear trend as to how quartz structures and exposure profiles change from the mining to the various production processes. Overexposure to silica quartz anywhere at the mine and production processes is considered unlikely, with the risk of developing silicosis being low. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013

Silica is a common silicon dioxide (SiO2) that can be crystalline or non-crystalline (amorphous). Amorphous silica is considered to be less hazardous than crystalline silica. Three dominant crystalline polymorphs exist, with silica quartz being the most common. Exposure to respirable crystalline silica (quartz) causes silicosis, a lung scarring disease. The aim of this study was to identify and quantify the silica exposure in respirable dust personal exposure samples, as well as in representative bulk samples which are large samples taken from the sources of airborne dust obtained from different mining and production plants involved in the production of titanium dioxide from beach sand. This is needed to determine the degree of risk of developing silicosis. Forty five workers employed in different mining and production plants participated in this study. Their eight-hour personal exposure to respirable particulate was determined. Personal respirable dust exposure samples and bulk samples were analyzed for silica by an accredited laboratory by means of X-ray diffraction based on NIOSH method 7500. Silica quartz was detected in personal respirable dust samples and bulk dust samples obtained from the mining and production plants, but amorphous silica was only detected in three personal exposure samples at the Slag plant and in the bulk sample obtained from the Roaster plant. All the silica quartz and amorphous silica concentrations in personal exposure samples were well below their respective exposure limits of 0.1 mg/m3 (quartz) and 3 mg/m3 (amorphous). No significant differences were found between the silica quartz concentrations in personal respirable exposure samples obtained from the mining ponds and the production plants, although a practical significance was found between some mining and production area personal exposure samples. The non-significant differences found between exposure concentrations and a practical significance suggest the necessity of involving a larger sample group in future. Other studies done in non-mining industries showed that some workers were over exposed to respirable silica dust. Compared to these findings the results of the present study showed the opposite, with respirable silica dust levels being below the South African action level and OEL. Further research, involving more samples, spread over a longer period of time, would probably be able to show a clear trend as to how quartz structures and exposure profiles change from the mining to the various production processes. Overexposure to silica quartz anywhere at the mine and production processes is considered unlikely, with the risk of developing silicosis being low. / Thesis (MSc (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2013

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No description available.

The characterisation of the properties of porous materials is of great importance in the effective management of natural and manmade systems. A sophisticated network model, 'Pore-Cor', of some of these properties has been previously developed. The present study has significantly extended the scope of the model's predictive capabilities. Flow and transport behaviour was examined in laboratory sand columns of various depths. These experiments examined unsaturated flow of water and conservative solute tracer transport through homogeneous sand samples. Flow through these was not homogeneous or repeatable. Experimental observations found that this may have been due to subtle random variations in packing, and the network model was shown to be able to simulate these. Solute transport of bromide was studied, applied both uniformly and from a point source. Both scenarios were modelled using a convection-dispersion equation, and it was demonstrated that the lateral component of such transport was highly significant. It was shown how convection-dispersion equation predictions of uniformly applied tracer transport might be improved by the application of the network model and a method for improving predicted lateral solute transport was outlined. It has been shown that levels of correlation in the distribution of differently sized voids within porous material may be responsible for large variations in permeability. This can make accurate modelling of permeability very difficult. A technique was developed for assessing the degree and nature of such correlations. The new method was tested on a variety of artificial and real samples and demonstrated to provide a quantitative assessment of such correlations. A method by which this could be used to improve network model simulations of materials possessing such correlation was described.