Groundwater Pollution Control in Fractured and Karstified Rocks

Abstract

Concepts of seepage flow and mass transport were originally developed for soils and rocks with granular structure and intergranular porosity. Fractured and karstified rocks are formed of blocks of solid rock (or matrix), intersected by discontinuities that may be locally developed into (karst) channels. Due to the intergranular, fracture and channel porosities, they represent a much more heterogeneous porous media. Detailed research into the flow mechanisms within the individual fractures and within the fractured media as a whole showed that the flow and mass transport through such media are scale dependants. Observation and description of the intrinsic structural features of the rock masses are scale dependant and so is the study of the flow and transport features of the fractured and karstified rock masses. The scale of the intended flow and mass transport study will predetermine the selection of the flow model type and, consequently, the selection of the observation technique furnishing the requested structural and flow detail. For small scale groundwater pollution problems (such as waste repository studies) the network and channel models will be applied. With large scale regional groundwater pollution problems, the use of the advection-dispersion models must be coupled with the proper internal aquifer regionalization. For such problems, also the flow and transport mechanisms within the unsaturated zone of the fractured and karstified aquifers should be given attention.