As part of a development programme in the Moretele II District, the Government of the Republic of Bophuthatswana, commissioned in 1983 the building of a dry system coal-fired power station. The lack of local surface water to cool the power station resulted in a decision to investigate the potential of the ground water resources. The resources will be required to supply an anticipated 30 year water demand. Because of the high capital investment and the importance of establishing an accurate assessement of the ground water potential there was a need for a comprehensive and detailed hydrogeological study. The specific aim of the investigation is to assess and quantify the long term reliability of the ground water resources. The very limited data for the area necessitated a particularly thorough and detailed investigation. This thesis describes the hydrogeological investigation carried out to define the ground water resource potential of this area. The main objectives of the study are to identify, recognize and evaluate the hydrogeological processes operating on this previously ill-defined Karoo aquifer. To achieve the research objectives the hydrogeological investigation was formulated to make use of various traditional geological, hydrogeological, geophysical and hydrochemical techniques in a logical framework. More specifically, the work involved a hydrocensus, a geophysical survey, the drilling of exploratory boreholes, aquifer tests to determine the intrinsic hydraulic parameters, water level measurements and the collection and analysis of water samples. The combined results of these various techniques provided data to quantify, evaluate and then propose management strategies for the identified resources. The study provided an understanding of the local hydrogeological conditions and has allowed for a conceptual model of the aquifer system to be derived

This study sets out to evaluate the use of geophysical methods for delineating buried stream channels, which can act as zones of preferential flow within a less hydraulically conductive aquifer. This information is important for gaining an understanding of flow dynamics of alluvial systems. The most reliable method of delineating the dimensions of aquifers is by drilling, which is an expensive proposition and is best preceded by a preliminary geophysical study to help define target zones for a drilling program. The study area is located adjacent to the Coerney River in the Sundays River Valley. Geologically it consists of approximately 5 metres of alluvial fines, covering 3 metres of coarse cobbles and boulders, all underlain by alternating siltstone and sandstone beds of indeterminate thickness. Throughout the area the water is very shallow at approximately 2 metres depth and the groundwater tends to be very saline. An air photo study revealed an old oxbow channel that had been covered over by subsequent agricultural land use. The geophysical methods available for the study were portable seismic refraction, electrical resistivity and electromagnetics. Preliminary field tests clearly showed that seismics did not produce valid results. The methods of electrical resistivity and electromagnetics produced good data and were subjected to further assessment. A grid was surveyed over the study area and both geophysical methods were applied at regularly spaced stations. Soil samples were taken over the same survey grid and analyzed for electrical conductivity in a soils laboratory. The results were compared to the geophysical data in an attempt to quantify the relationship between geophysical response and soil salinity. The data from the electromagnetic survey showed areas of low electrical conductivity which was a possible indication of zones of preferential groundwater flow. A transect of boreholes was drilled over selected electrical conductivity lows and successfully intersected the buried stream channel. A comparison of the borehole logs with the layered earth models from the Vertical Electrical Soundings indicated that the electrical resistivity method was not responding to the features of the buried stream channel and the cobblestone layer. This proved the electromagnetic method to be more valuable for this particular study

The investigation reported in the thesis concerns an area south and west of Graaff-Reinet, in the Cape Province. The research projec t identified the existence of four groundwater units. The aquifers predominantly occur in Beaufort Group sediments and the boundary of each unit is formed by dolerite intrusives or with topographical highs. The objective of the study was to quantitatively assess these units in terms of both quantity and quality for possible future development as a municipal supply for Graaff-Reinet. In order to achieve the objective, fieldwork was carried out involving a hydrocensus, geological mapping, drilling, aquifer testing and hydrochemical sampling. The analysis of these data revealed that the Sundays and Kamdeboo aquifer units are unsuitable for further development. The Moordenaars and Swart units, both of which produce good quality water, have a combined exploitation potential in the order of 30 000 m³ /d. / KMBT_363 / Adobe Acrobat 9.53 Paper Capture Plug-in

This work examines the use of gravity data and its application to subsurface water reservoirs in the immediate vicinity of the South African Geodynamic Observatory, Sutherland (SAGOS), situated in a semi-arid region of the Karoo region of South Africa, and underlain by the Karoo sedimentary rocks intruded by dolerite dykes and sills. SAGOS houses the only supergravity metre (SG) in Africa, and this thesis sets out to test its use in monitoring groundwater dynamics using hydrological and gravity data. The main aim of this work is the application of the SG data, in conjunction with hydrological data, to better understand episodic recharge of subsurface reservoirs. The importance of water as a resource, globally and specifically the Karoo, is reviewed in conjunction with supply and demand of water. This is to contextualise the socio-economic, technical as well as policy issues related to water resource management. Applicable technologies for water resource management and efficient water use are highlighted and the application of gravity to hydrology is introduced, including satellite as well as ground based tools. In addition, arid zone hydrology as well as recharge and its mechanisms are analysed in order to better understand these processes when examined from gravity measurements. Issues related to understanding flow within the vadose zone as well as in secondary aquifers are examined, and gravity residuals and subsurface hydrology are highlighted. Thereafter, a conceptual groundwater flow modelof the study area is developed using multiple tools. First, the geology around SAGOS was mapped using SPOT 5 imagery and then ground truthed. Second, stable isotopes and water chemistry analysis was undertaken on water samples from selected boreholes. The results allude to preferential flow acting as the main mechanism for groundwater recharge. Follow-up pump-tests illustrate that fracture connectivity is greatest at close proximity to the dyke. Soil mapping, using aerial photography was also undertaken. Duplex soils, enriched with clay at depth, dominate the study area. Using in-situ infiltration tests, it is shown that the alluvium, which lines the river beds, has a higher hydraulic conductivity than the other soils, confirming that these streams act as preferential conduits for subsurface recharge. Precipitation events were correlated against gravity residuals at 4 wells, over different time periods. The results are examined using time series analyses. Gravity residuals from well SA BK07, over a period of 24 hours after the rainfall event, delineate instances of negative correlations, as well as strong positive correlations (of up to 0.9). On the whole however, correlations between gravity and groundwater at SA BK07 are variable and weak, and in conjunction with water level measurements and water chemistry, the data suggest that this well is located in a dynamic conduit (throughflow) and not in a permanent groundwater reservoir. By contrast, other wells show strong positive correlations between gravity residuals and water levels following episodic recharge events for a later time series. Correlations between the water levels and gravity residuals in wells SA BK04, SA BK05 and SA BK 01 are in excess of 0.7 for specific rainfall events. In summary, the results suggests that gravity is an excellent tool for measuring episodic groundwater recharge within the immediate vicinity of the SAGOS. This implies that gravity can aid in monitoring groundwater losses/gains in arid and semi-arid areas. Recommendations for future work are highlighted at the end; these include the possible use of hydrological modelling of reservoirs at various scales and then comparing these results to the SG as well as GOCE and GRACE satellites data, and then improving numerical modelling of the groundwater dynamics for sites like Sutherland and the surrounding arid Karoo region, where sparse water shortages, and potential pollution related to fracking for shale-gas, are likely to compete with established water needs for farming and human consumption. It is also suggested that the gravity modelling be examined to better understand site specific scenarios and thus aid in improving the processing of the gravity signal.

No description available.

MESMEG / Department of Mining and Environmental Geology / See the attached abstract below

MESHWR / Department of Hydrology and Water Resources / See the attached abstract below

MESMEG / Department of Mining and Environmental Geology / This dissertation focused on the assessment of borehole yields within the Nzhelele- Makhado area, which is located in the northern part of South Africa within the Vhembe District Municipality of Limpopo Province. The aim of the study was to identify factors that influence the yields of water supply boreholes within the study area. This information will be used to improve the groundwater resource knowledge required in assessing the potential of groundwater resources in augmenting the Nzhelele Regional Water Supply Scheme. The study area is mostly underlain by the ‘hard rock’ formations of the Soutpansberg Group, which practically has no primary porosity. The groundwater is residing mainly within the weathered and fractured or discontinuities, considered being secondary porosities. Due to the complexity of the underlying fractured and hard rock aquifer systems and the fact that most of the boreholes drilled in the area were not scientifically sited, the study area is dominated by very low yielding boreholes. Majority (48%) of the boreholes were drilled into the Nzhelele formation due to the fact that it occupies the central, relatively flat and low lying sections of the study area. The variations in average yields in boreholes drilled in different formations within the study area is relatively low suggesting that the difference in lithology of different formations do not to have any major influence in the yields of boreholes. The topographical settings of the area do not have any influence in the borehole drilling depths and yields. The high borehole yields in shallow boreholes located in mountainous areas is due to local groundwater systems, which recharges and discharges locally. Mapped lineaments are slightly low yielding (average yield of 0.32 l/s) compared to the faults (average yield of 0.43 l/s) within the study area. Boreholes drilled along the NE-SW trending lineaments support double the yields (0.41 l/s) on average of those along the SE-NW (0.28 l/s) and W-E (0.20 l/s) trending lineaments. The high yields in boreholes closer to non-perennial streams compared to perennial rivers is due to the fact that non-perennial streams are comprised of thick layer of overburden capable of supporting high yielding boreholes, whereas the overburden along the perennial rivers are washed away during rainy season leaving bedrock exposed or covered with thin layer of sediments. The proximity to the young faults trending SE-NW and dry non-perennial streams has proved to be the most the favourable areas for development of high yielding boreholes in the study area, compared to lithological difference and topographical settings of the area. However, it should be noted that there are no simple relationship between various factors that control the yield of the boreholes in the area. Despite the similarities in some factors that influence borehole productivity on a regional scale such as faults and drainage systems, the complexity of the weathered-fractured aquifer system suggests an over-riding influence of local features, which results in significant variations in yield and response to abstraction. / NRF

Thesis (MA (Geography and Environmental Studies))--University of Stellenbosch, 2007. / The Western Cape province of South Africa is a water scarce area with a Mediterranean climate. The majority of rainfall occurs in the cold winter months and the area experiences hot and dry summers. Studies done to investigate various water supply and water demand management options for the City of Cape Town, concluded that the Table Mountain Group (TMG) aquifer has the potential of yielding high volumes (estimated at 70Mm3/a) of good quality water, but that further research about this source as a potential augmentation supply to the City of Cape Town was necessary before extraction could commence. The aim of the study is to develop a spatial decision support system (SDSS) to be used by a hydrogeology project team, which includes hydrogeologists, environmentalists, ecologists, engineers and other stakeholders. The Table Mountain Group Aquifer (TMGA) SDSS is meant to be a decision support tool, but should also raise awareness about the use of spatial data and information and its capabilities for earth science and other multidisciplinary applications. By means of team discussions and interviews data, spatial analysis and data manipulation requirements were determined. Based on these requirements, four spatial analysis tools were developed. The spatial tool named “Borehole Analysis” analyses stratigraphic information obtained from existing boreholes and hydrogeological point data. The tool determines what groundwater use and monitoring has been undertaken in the area of interest. The “Topographic Analysis” tool identifies any topographical (e.g. rivers) and cadastral (e.g. farm boundaries) data within a certain distance from a possible borehole site. The “Sensitive Area Analysis” tool addresses queries with respect to sensitive areas, such as wetlands, statutory protected areas and private nature reserves. The “Image Classification” tool gives the team members an opportunity to use band ratios during image interpretation. The TMGA SDSS was developed using TNTmips v70, Extensible Markup Language (XML) and Spatial Manipulation Language (SML) and can be run on TNTAtlas v70, which is a free software. The TMGA SDSS enables the team members to have equal and ready access to data acquired by other members. This was found to support intra- and interdisciplinary conversation and facilitate understanding of how the data is being (or could be) used. It also contributes to levels of confidence in decision-making and supports a holistic approach to project design and implementation. Keywords: decision-making, geographic information system (GIS), spatial decision support systems (SDSS), spatial manipulation language (SML)

The study presents the spatio-temporal assessment of groundwater-surface water (GW-SW) interaction aspects in the Schoonspruit River catchment, North West of South Africa. The research study aimed at improving understanding of groundwater and surface water interaction through assessing its location and time when such interaction occurs. GW-SW interaction sites were identified using principal aquifer type characterization methods. The occurrence of the interaction was established using hydrochemistry methods and the effectiveness of the existing monitoring methods were evaluated in their consideration of GW-SW interaction within the study area. The main results from the study showed that there was GW-SW interaction in the Schoonspruit River catchment which was not affected by seasonal changes. The result further showed that existing monitoring methods in the study catchment were not effective in addressing GW-SW interaction. The study concluded that qualitative methods are essential in studying GW-SW interaction and that monitoring methods for such interactions are required / Centre for Sustainable Agriculture and Environmental Sciences / M. Sc. (Environmental Management)