FIG. 1. Conceptual physical nonequilibrium models for water flow and solute transport. In the plots, is the water content, _mo and _im in (b) and (c) are water contents of the mobile and immobile flow regions, respectively; _M and _F in (d) are water contents of the matrix and macropore (fracture) regions, respectively, and _M,mo, _M,im, and _F in (e) are water contents of the mobile and immobile flow regions of the matrix domain, and in the macropore (fracture) domain, respectively; c are concentrations of corresponding regions, with subscripts having the same meaning as for water contents, while S is the total solute content of the liquid phase.