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Exploration of deep, previously unknown semi-fossil aquifers of the Kalahari Basin (southern Africa)

Author:
Bäumle, Roland, Himmelsbach, Thomas
Source:
Grundwasser 2018 v.23 no.1 pp. 29-45
ISSN:
1430-483X
Subject:
aquifers, basins, fossils, freshwater, groundwater, hydrologic cycle, rivers, tectonics, Angola, Namibia
Abstract:
Unlike fossil groundwater reserves, semi-fossil aquifers are still integrated in the hydrological cycle and hence, partially renewable. In Africa, semi-fossil aquifers provide an important freshwater resource that is not yet fully explored. Two recently discovered, deep porous aquifers in the northern parts of the Kalahari Basin are currently investigated, namely the Ohangwena II (KOH-2) aquifer in the border region of Namibia and Angola and the Lower Kalahari Aquifer (LKA) in northeastern Namibia. The hydrogeological characteristics of the KOH-2 are largely determined by the sedimentary structure that was defined as a paleo-delta whereas the LKA is influenced by the tectonic setting within an incipient rift zone that has repeatedly led to river captures. Hydrochemical and hydroisotope results for the LKA indicate that a presumably brackish groundwater body is undergoing “freshening” since the Late Pleistocene. The exploration of such deep groundwater systems must focus on the identification of main geological, tectonic and sedimentological structures.
Agid:
5893860