Rock fracture characterization and discrete network modeling and its implication for groundwater flow in crystalline rocks of south-eastern Ghana

Information on the role fracture properties plays in groundwater flow and solute transport in crystalline rock masses abound. This study uses the discrete fracture network (DFN) modeling approach from 1128 fractures spanning along 238 m of linear scanline, and 14 circular scanlines to determine mean porosity and permeability of some crystalline rocks in the Togo structural units of south-eastern Ghana. Linear intensity ( P 10 ) and areal intensity ( P 21 ) were determined, while spatial fracture intensity ( P 32 ) and hydraulic properties were estimated from the DFN modeling. The estimated mean porosity is 0.38 for a representative elemental volume of 8000 m 3 , while the horizontal and vertical permeability values range from 10 –3 to 10 –4 and 10 –4 to 10 –6 m/s, respectively. The study concludes that scanline mapping data can be effectively used to project field information at outcrop scales to produce 3D models of discontinuity networks in the crystalline rocks. Results from the study can be of relevance during the siting of waste dumps and water supply sources. The approach would be suitable for the characterization of similar terrains for water resource supply and waste disposal site selection.