Characterization and quantification of preferential flow in fractured rock systems, using resistivity tomography

Abstract

In the use of unsaturated zone methods to estimate recharge, the basic assumption is made that recharge occurs by means of diffusive processes (i.e. piston flow occurs). In fractured environments the reliability of recharge estimate have been questionable due to preferred pathways influencing the recharge flux. These preferred pathways have been shown to occur throughout sub-Saharan Africa. The focus of this study is to develop improved methodologies to quantify preferential flow in fracture environments. From the quantification of preferential flow pathways it will be possible to differentiate/identify fast flowing (by-pass through fractures) and slow flowing (water in matrix) conduits. This will lead to the estimation of proportions of slow and fast flowing pathways.