Hydrogeological Investigation In Namaqualand, Kakamas Area, South Africa

In southern Africa, crystalline basement aquifers constitute approximately 55% of the land area and therefore it is important to understand these aquifers and the mechanisms that control them. These aquifers have been well documented in the northern parts of South Africa however the amount of research done on the central Namaqualand basement aquifers is severely lacking, especially in the area surrounding Kakamas in the Northern Cape (the study area). Therefore a detailed hydrogeological study was conducted in the area by means of a thorough hydrocensus, pumping tests and a geological evaluation of the area. The hydrogeological tests were conducted on various boreholes in the study area, close to Kakamas. In an attempt to better hydrogeologically classify the aquifers that are prevalent in the area, the data from the hydrocensus and pumping tests were evaluated in conjunction with the specific geology of the area, as Namaqualand aquifers are very much structurally controlled by the geology. There are three types of aquifers (alluvial, weathered zone and fractured basement rock) that are superimposed on each other throughout the study area. These aquifers are strongly interlinked as groundwater flows from one to the other. The data obtained from the boreholes varies across the study area. When evaluating both the pumping test data and the site specific geology it is evident that on geological contact zones and areas where the geology is more faulted the boreholes have higher yields. The study indicates that boreholes targeting alluvial aquifers that overlay basement aquifers in faulted valleys or contact zones are the best source for sustainable groundwater in central Namaqualand.