Hydraulic properties of the Table Mountain Group Aquifers

This research attempts to provide a new insight into the fractured rock aquifers, with case studies on the Table Mountain Group (TMG), South Africa. Multiple approaches were employed to characterize the highly heterogeneous sandstone aquifers in order to estimate associated aquifer properties such as porosity, storativity and hydraulic conductivity. Aquifer media study with focus on the nature of the fractures or fracture networks was conducted in detail. The establishment of aquifer conceptual models is helpful to have a better understanding of groundwater behaviours in the fractured rock aquifers. Results show that porosity of the TMG sandstones is strongly scale-dependent. The fractured rock hydraulic conductivities (K value) were estimated by using a hydraulic conductivity tensor and hydraulic test methods. These K values at most of the sites fall in the range from 10-2 m/d to 10-3 m/d; however they decreases at depth. 3-D fracture network model demonstrates that very few fractures in the sandstone aquifers are interconnected and contribute groundwater flow in the fractured rocks.

L. Lin , PhD: Hydrogeology at the University of Western Cape. Specialist Scientist at Council for Geoscience, South Africa.