Groundwater resource assessment for development and use in Jozini, KwaZulu-Natal

English: Due to a shortage of surface water, coupled with the current drought situation that has befallen South Africa, groundwater plays an important role in the water supply for domestic users; mostly for the rural communities in South Africa. Groundwater resource assessment aims to obtain significant data and information required to describe the hydraulic and chemical parameters for the estimation of the available groundwater resource suitable for human consumption. A study was undertaken for groundwater resource assessment for the rural town of Jozini in Northern KwaZulu-Natal, South Africa. The field investigations included the use of geophysical methods, and for this study magnetic (G5 Proton magnetometer), together with electromagnetic methods (Geonics EM 34-3 system) were chosen as the preferred methods. The reason for the magnetic method was because it is easy to operate, analyse and interpret the anomalies from a possible structure such as a dolerite intrusion. On the other hand, the electromagnetic method was chosen, because it determines the resistivity of the rock, and the resistivity of variations with depth and lateral extent of geological structures, whereupon these variations are then interpreted to identify the drilling targets. Based on the results of the geophysics, drilling targets were sited, and seven boreholes were drilled using rotary percussion air drilling. Blow yields for the newly drilled boreholes ranged between 0.14-2.28 l/s, which is an indication of low yielding to moderately yielding boreholes. An aquifer pumping test was conducted on all newly drilled boreholes and existing four boreholes, for the duration of between 9 hours and 22 hours. Pumping test for the existing boreholes was conducted by another external consulting company, during their refurbishment. The aquifer parameters were estimated using the Cooper-Jacob (1946) method and the Theis recovery (Theis, 1935) method. The general groundwater flow in the study area is from both the fractures and from the matrix, as seen from other boreholes. The combined yield of 0.95l/s (0.0821 ML/d) was estimated from all eleven boreholes (seven newly drilled and the four existing boreholes). These sustainable yields are very low and cannot sustain the requirement in the study area. The groundwater quality assessment reveals that there are two dominant water types in the study area namely: the NaCl water type (42%) and the Na-HCO3- water type (28%), other samples show a mix of water types. The conclusion was therefore made that although the area is characterised by low yielding boreholes, the municipality with the help of the DWS should drill more boreholes which will supplement the existing and newly drilled boreholes. It is then recommended that when drilling boreholes for water supply in the study area, the host rock (rhyolite) or the intrusion should be targeted as these areas have shown to have a bit higher yields than the boreholes which were drilled targeting the contact between the host rock and the intrusion.