ABSTRACT
ABSTRACT: The methodology of testing and verification of a hydrogeological working hypothesis in regions with scarce hydrological data is demonstrated in the case of the Table Mountain Group (TMG) of the Cape Provinces of the Republic of South Africa (RSA). The rocks of the TMG group have no primary porosity and were considered to be water bearing only in the uppermost shallow part near the surface. The existence of thermal springs along regional faults suggested an alternative conceptual model, in which the fault zones are fractured permeable media, enabling flow into great depths over long distances. Testing and verifying this conceptual model were done by sampling and testing for the environmental isotopic composition (oxygen 18/16, hydrogen 2/1) of the perched water table springs along a section from the sea to the mountains. This proved that the mountains are the areas of recharge of the thermal springs. The high temperature of the water is a function of flow to great depths along the regional fracture zones.
