Bloemfontein currently receives most its water from three sources, via the municipality, the Maselspoort Scheme and the Caledon-Bloemfontein Transfer Scheme. Purified water is transferred over more than 110 km from Welbedacht Water Treatment Works (WTW). A comparison done on the volumes of water pumped into the city and the metered water use shows that about 39% (24.55 million m³/annum) of the water is unaccounted for. These losses suggest that illegal connections and failing infrastructure may be behind the issue. In 2014, a project was launched to investigate the possibility of augmenting the water supply from groundwater sources. This offers various advantages over surface water such as: being a resource that does not require transport over long distances, it is more resistant to drought (short term), groundwater’s natural quality is usually good and groundwater resource can be developed further as the need increases.
In South Africa, the role of groundwater is often underestimated despite two thirds of our population being dependant on it for livelihoods, health and dignity. It has been estimated that the total volume of renewable groundwater in South Africa has been estimated at 10.34. Billion m³ per year with only 2-4 billion m³ currently being used. There is great potential to increase groundwater supplies in South Africa.
The investigation will comprise of:
- The conduction of a hydrocensus to locate groundwater users, information on groundwater quality, quantity and use will be gathered.
- Geophysical surveys will be conducted focusing on undeveloped areas and open fields which are assumed to overlie the edge of the known ring- dyke. After geophysical interpretation of these areas are done, borehole systems will be installed.
- Hydraulic tests will be conducted and based on results, sustainable abstraction rates will be calculated.
- Groundwater sampling will take place at all new and existing boreholes and results will be submitted for analysis to determine suitability for consumption.
Bloemfontein is underlain by dolerite sills and dykes of different shapes and sizes. These intrusive structures are often associated with exploitable groundwater. There is a prominent ring-dyke known to partially underlie the city as various outcrops are visible at several locations within the city boundaries. Around this area, there is a number of privately owned boreholes which yield successful results.
The results of the investigation, using various magnetic ground studies, revealed the presence of a broad, almost linear magnetic feature which ran across the study site. The shape of this feature suggests the presence of a dyke-like structure. The dyke is being considered as the primary target for groundwater exploration in the current project.
Currently, the project is still undergoing its initial phase. Limited geophysical investigations have been completed but have produced encouraging results. The ring-dyke structure gives distinct geophysical responses that aid in facilitating interpretation of the anomalies recorded across it. The possibility of installing high yielding boreholes in these aquifers associated with the dyke appears promising.
[This is a summary of “ Investigating the Potential of Using Groundwater Associated with a Ring-Dyke to Augment the Municipal Water Supply to Bloemfontein” – by Makoae, Molaba, van der Merwe and Fourie – link to the article may be found below]
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