Hydrogeological characterisation and water supply potential of Lebalelo South, Limpopo Province of South Africa

Abstract

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.