Review: Groundwater resource occurrence in Hout river gneiss crystalline basement formation in the Limpopo Basin, South Africa

Understanding the occurrence and sustainability of groundwater resources within the crystalline basement lithological environment in most parts of Africa is of paramount importance as in most cases it is the only available water resource for domestic consumption and agricultural use. Moreover, the abstraction of groundwater resources within such aquifers often proceeds without a thorough understanding of groundwater processes that controls the availability and groundwater occurrence of the system. The Hout river gneiss crystalline basement aquifer system, situated in the Limpopo province of South Africa is a particular example of such aquifer system where groundwater abstraction is substantial and the knowledge of groundwater controls within the system is not fully understood. This paper reviews the hydrogeologic setting and factors that potentially influences the groundwater occurrence and utilisation within the Hout river gneiss crystalline basement formation which is part of the Limpopo Mobile Belt in South Africa. The study provides an understanding on the major drivers of groundwater resource occurrence, hence areas of high groundwater potential within the formation. It discusses how geological structures such as NE-SW trending diabase dykes and pegmatitic veins influence the aquifer compartmentalization within the weathered regolith and the fractured rock units within the crystalline basement system. The work presented herein lays a platform for future groundwater development and research within the system, thereby enabling the establishment of the facts which control the groundwater occurrence and dynamics within the Hout river gneiss crystalline basement aquifer formation.