Hydrology
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Browsing Hydrology by Author "Kelbe, B.E."
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- ItemDeveloping a low-cost ceramic micro-porous water filter for removal of microorganisms that cause common diseases(University of Zululand, 2012) Simonis, Jean Jacques; Kelbe, B.E.; Revaprasadu, N.; Basson, A.K.Africa is one of the most water-scarce continents on earth and the lack of potable water is responsible for the death of approximately 4 900 children every day. Water can be effectively decontaminated by using a household ceramic water filter. The local production of low-cost water filters suitable for the removal of suspended material and pathogenic bacteria from water sources, especially in rural areas, provides a promising solution to the problem and is therefore important to pursue. The traditional slip casting process was used develop a micro-porous ceramic water filter. The method was found to be more suitable than either extrusion or die casting for manufacturing a locally suitable, low cost ceramic water filter. Slip casting, requiring limited expensive equipment, usage of locally available raw materials, labour and expertise makes this the only promising method for manufacturing ceramic filters in a rural, non-technical setting. Using milled lithium alumino-silicate had the main advantages of thermal shock resistance and dimensional stability because of the material’s zero thermal expansion at firing temperatures. Milling tests based on the Andreasen packing model were used for obtaining the best particle packing for the raw material recipe. The material also provides dilatant rheology matching the rheology of the organic carbon poreformer. The candle- type filter required less raw material compared to the other low cost filter such as the pot- type filter from (PfP). The particle size of the pore-former provided us with small pores around 3 microns after firing for the elimination of bacteria from drinking water. These pores were much smaller and more effective when compared with Potters for Peace (PfP’s) pore size of 16-25 micron. The zero thermal expansion (adopted ZTE product name) helped to prevent damage (cracking) to the product during heating and gave accurate control of the ultimate filter size after sintering. The large apparent porosity results of between 67-73 per cent for the finished product provide a specific surface area of 7 m2 g-1 and a high flow rate which explains the filtration efficiency of the filter. The 32 minute retention time of water further helps with the filtration effectiveness. Bacteriological testing exceeded all expectations. The product was tested using water contaminated with high concentrations of selected bacterial cultures as well as with water from local polluted streams. -i v - The product complies with the WHO (2011) recommendation requirement for household water treatment (HWT) technologies of a LRV ≥ 4 (log reduction value). With correct cleaning and basic maintenance, this filter can effectively provide clean drinking water for rural families affected by polluted surface water sources. This product can immediately be useful to families placed in situations where polluted drinking water causes distress. The filter could provide a low-cost solution for the millions of people without access to potable water in Africa. Furthermore, such a project provides opportunities for local financing and innovation. The method of slip casting for the manufacture of porous ceramic used in this study has been showed to work very successfully. The filter requires fewer raw materials, energy for the shaping- and firing- process, finishing, storage space, it is small, compact, and more effective against bacterial load and has a flow rate 3-4 times faster than any other low cost manufactured filter. The low unit manufacturing cost, places Outbac in a strong position, to also compete on a price-only-basis with other low cost, ceramic filter producers in the world.
- ItemA geohydrological study of the Richards Bay area(1999) Germishuyse, Talita; Kelbe, B.E.Numerical methods such as groundwater models can play a vital rplein understanding the dynamics of an aquifer provided that the input data is accurate and sufficient to represent the environmental system adequately. The groundwater flow mode! used in this project requires specific information about geological features, hydraulic properties as well as recharge and evapotranspiration. All the available information has been collected and interpreted to use.in the model. There is a need to develop conceptual models of the region for theicnplementation of the numerical methods. The regional geology is well described in the literature, but observations on a local scale do not always conform to the?regional stratigraphy. Consequently, many assumptions have been made in the construction of three conceptual models, namely a single layer model, a multi-layer model with homogeneous hydrological properties and a heterogeneous multi-layer model. MODFLOW (McDonald and Harbaugh, 1983), a quasi three dimensional, finite difference, groundwater flow model, was used to determine the regional groundwater flow patterns in the Richards Bay area. A summary of the theory and parameterization process used in the model is presented. Considerable detail is offered for the conceptual modelling of specific processes not incorporated in the finite difference scheme of the numerical model. These include recharge and evapotranspiration. The model domain and parameters that were used in the model as-well as the calibrations are described. For Hie general flow pattern for the region, the groundwater divides for each catchment were determined and are presented in relation to the diverse land use sectors. The project identified the different land use sectors within the principle catchment areas of the main water resources of the region. In particular, it provided a demarcation of which parts of the Richards Bay Industrial sectors could influence the water quality of the various water bodies of the region.
- ItemSpatial modelling of the contributions from surface and subsurface water to river flow in catchments(2007) Snyman, Nina-Marié; Kelbe, B.E.The groundwater and surface water resources were historically modelled separately because of laws of the governing bodies. Movement towards equity and sustainable development demands the integration of groundwater and surface water in decision making and modelling of these water resources. This research attempts to simulate the contributions in river runoff from surface and groundwater resources, by conceptualizing the flow pathways of the different resources present in a river's catchment. It utilizes the spatial information of the catchment, along with the observed flow hydrograph characteristics, to create a model of the flow components in the river runoff sequence. The model conceptualizes the observed flow hydrograph from a rainfall event as a combination of flow from three different pathways. Excess rainfall (the part of measured rain that causes the storm hydrograph) is separated into the surface runoff; the throughflow (through the unsaturated soil structures and macropores); as well as baseflow (through the deeper saturated soil structures of the catchment): All of these components contribute to the measured flow at the catchment outlet. Analysis of observed flow hydrographs (i.e., the separation of the observed flow into different flow components); indicates constant recession rates for each flow component present in the hydrograph. Information derived from observed flow hydrograph analysis includes the recession rate of each flow component, the percentage of water that is allocated to each flow component for a particular storm event, and the times to peak and recede. This information is used along with the spatial information of the catchment, to derive a simulated flow hydrograph for a rainfall event, for each flow path. The Digital Elevation Model (DEM) of the catchment and geological features are used to determine the pathways and distances that water travels to the outlet. Flow velocities, along these pathways, are influenced by the slopes and the roughness of the medium over/through which the water travels. The flow velocities are estimated from adaptations of recognized hill slope and channels flow velocity equations. The channel geometry, that determines the flow rate through each catchment segment in the DEM, is derived from the contributing area and scaled by the total catchment size. Cumulative flow times along each pathway are used to derive a flow response function for each flow component. These response functions are unique to each catchment and represent the equivalent of a unit hydrograph for each flow component. These response functions are scaled and superimposed to simulate the observed storm hydrograph of a rain event. Storm events are divided into four scenarios representing a combination of high and low intensity rainfall events, as well as events of long and short duration. The model is applied to a rainfall series of five months in the Ntuze research catchments, during which various rain storm types occurred. Model parameters are applied to the much larger Goedertrouw Dam catchment to evaluate the transferability of the model.