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

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)

Hydrogeologists have faced serious challenges worldwide in the characterization of fractured rock aquifers due to the heterogeneous nature of the imbedded geology. The bulk flow parameters in the Karoo strata in South Africa are specifically uncertain since most models are based on homogenous block systems. As part of a WRC research project, entitled “Measurement of the bulk flow and transport characteristics of selected fractured rock aquifer systems in South Africa”, this study focuses on the characterization, borehole drilling, flow parameter measurements and groundwater quality assessment of the Balfour Formation in the Beaufort Group of the Karoo Supergroup in the Eastern Cape, South Africa, which is seriously heterogeneous in deposition and has also been largely neglected as drilling targets for groundwater. The Balfour Formation comprises mostly mudstone, shale and sandstone, formed in a braided and meandering river system. In addition to the heterogeneous deposition, the flow pathways in this aquifer system are not fully understood due to lack of actual measurement data. The methods used in this study include field mapping, site characterization, borehole drilling, and pumping and tracer testing in order to obtain the borehole yield, aquifer transmissivity, storativity and groundwater flow velocity. In addition, the groundwater chemistry was also studied to determine quality for use and possible connectivity with the nearby Tyume River and to determine potential sources of groundwater contamination. The results obtained include: 1) The study area is predominantly mudstone/shale with thin layers and lenses of siltstone and sandstone, which are interbedded; 2) Two boreholes were successfully drilled, which had yields in excess of 10 l/s in four water levels (at 7, 22, 54 and 65 m); 3) The estimated average transmissivity is 246 m 2/day according to the recovery test; 4) The estimated seepage velocity is 120 m/day according to tracer tests in the aquifer between the two boreholes which are 5 m apart; and 5) The water chemical type is the combination of HCO3-, Cl-and SO42- , which is distinguishable from that of the Tyume river; 6) There is no evidence for groundwater recharge to the deep aquifers from the Tyume river, based on the differences of the water chemistry; 7) The elements Ca, Cl, Na and C are distributed more than 90% as free ion species in BH2 borehole water; and 8) The groundwater in BH2 borehole is undersaturated (negative SI) with respect to some minerals (for example: anhydrite, fluorite, gypsum and halite), oversaturated (positive SI) with respect to some minerals (for example: aragonite, calcite and dolomite). It is concluded that there is a great potential to obtain drilling targets for high yielding boreholes in the sedimentary rocks of the Balfour Formation in the Karoo Supergroup.

MESHWR / Department of Hydrology and Water Resources / Lebalelo area of Sekhukhune district is one of many areas in South Africa experiencing portable water scarcity, especially during prolonged dry season. Due to the dominance of low yielding aquifers in South Africa, it is essential to manage groundwater resources in these low yielding aquifers. However, the management of low yielding aquifer is difficult in areas like Labelelo where the hydrogeological characteristics of the aquifers are understudied. This study investigated the hydrogeological characteristics of the aquifers in the area using combined geophysical method and analytical groundwater models. Four newly drilled borehole and five existing boreholes were used for this study. Geophysical survey was carried out using magnetic and electromagnetic methods. The magnetic survey was used to locate the position of magnetic bodies such as dolerite dykes and different lithologies with different magnetic properties. The electromagnetic survey however, was used to determine zones of high permeability associated with the intrusive bodies as well as high permeability zones in fault planes. Step test, constant discharge test and recovery tests were conducted on all the boreholes to stress the borehole. This was used to determine a suitable and sustainable pumping rate of the aquifer. Pumping test data from the pumping period and recovery was evaluated and interpreted using AQTESOLVE. Aquifer transmissivity, storativity, internal and external hydraulic boundaries were determined from the data. The transmissivity in the area ranges from 0.08 to 124.7 m2/day. The aquifer types in the area are double porosity aquifer, radial flow aquifer with single porosity. Inductive Coupled Plasma (ICP-MS) was used to measure heavy metals, trace metals and cations while Ion Chromatography (IC) was used to determine anions in groundwater of the study area. The groundwater in the area is dominated by calcium carbonate as a result of long residence time with dolomite. The hydrochemistry of the water indicates that the chemistry of the groundwater in the area is mainly controlled by rock-water interaction. / NRF

MESHWR / See the attached abstract below

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