ABSTRACT
Rill flow is deeper and speedier than inter-rill flow and is characteristically turbulent. It is a sporadic concentrated flow that grades into streamflow.
Subsurface flow Flow within a rock or soil body may take place under unsaturated conditions, but faster subsurface flow is associated with localized soil saturation. Where the hydraulic conductivity of soil horizons decreases with depth, and especially
zone, springs arise where the water table is almost permanent. Once a spring starts to flow, it causes a dip in the water table that creates a pressure gradient in the aquifer. The pressure gradient then encourages water to move towards the spring. Several types of spring are recognized, including waste cover springs, contact springs, fault springs, artesian springs, karst springs, vau - clusian springs, and geysers (Table 9.1).
