ABSTRACT
The porous medium below the land surface can be divided into two zones: one between the water table and the land surface, and the other below the water table. The water table is defined as the surface on which the fluid pressure in the pores of the medium is exactly atmospheric. This means that the hydraulic head at any point on the water table must equal the elevation of the water table at that point. The porous medium below the water table is saturated, that is the pores are filled with water, and can be referred to as ground water or saturated geologic zone. As shown in Figure 11.1, the porous medium above the water table is often divided into three zones: (1) capillary fringe, (2) intermediate zone, and (3) soil moisture zone (also called rootzone).
