Figure 2.
In many fractured-rock systems it is useful to conceptualize the rock as comprising two domains: (1) the mobile porosity (blue) consisting of connected permeable fractures, and (2) the immobile porosity (red) consisting of dead-end, disconnected or impermeable fractures and the rock matrix. Advection of solutes occurs only in the mobile porosity, and exchange occurs locally between the two domains according to various forms of diffusive rate-limited mass transfer (Carrera et al., 1998).
