oa An integrated approach with DighemV to groundwater exploration – Tsabong, Botswana

Exploration for potable groundwater to supply settlements in the southern Kalahari Desert of southwestern Botswana is currently in progress. A Dighem survey was flown over outcrops of Precambrian rocks after target areas were selected in an initial desktop study. The study included some preliminary ground geophysics, reviewed all available information in the area and completed an interpretation of remotely sensed (Landsat TM and SPOT) and aeromagnetic data. Two target areas were recommended for Dighem airborne electromagnetic (AEM) surveying near outcropping basement. The Dighem survey was designed to map faults and fractures intersecting resistive quartzite of the Olifantshoek Sequence, the most productive groundwater host in the area. Outcrop geological mapping, ground geophysical traverses to test previous successful boreholes and to locate new ones, exploration drilling and borehole logging were then used to follow up and refine targets generated from the AEM survey.

Airborne and ground geophysical survey data were carefully integrated with outcrop geology and borehole information. An improved understanding of the geology and structure in Precambrian Olifantshoek quartzite was based on interpretation of the Dighem and aeromagnetic data. Exploration drilling success is attributed to an integrated multidisciplinary approach, which is strongly recommended for other potential groundwater projects in the Kalahari Desert.