The hydrogeology of the Uitenhage Artesian Basin with reference to the Table Mountain Group Aquifer

Abstract

The Uitenhage Artesian Basin (UAB) lies in the Eastern Cape and is South Africa’s most important artesian groundwater basin, supplying approximately 1 400 Ml/yr (44 l/s) of water from springs for domestic use to Uitenhage, as well as supporting large citrus irrigation schemes. Groundwater from this basin has been extensively utilised from the early part of the 20 th century, including periods of over-exploitation resulting in the declaration of a groundwater control area to limit abstraction to sustainable rates. The aquifer comprises fractured Table Mountain Group (TMG) sandstones confined in the eastern part of the basin by overlying Cretaceous siltstones and mudstones, resulting in artesian conditions. The Coega Fault is a major structural feature dividing the basin into separate systems, viz. the southern Swartkops Aquifer and the northern Coega Ridge Aquifer, that are hydrogeologically independent of each other. The Elands River syncline divides the Swartkops Aquifer further into the Kruisrivier and Bethelsdorp Units.

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