PREFERENTIAL FLOW IN A SANDY VADOSE ZONE .2. MECHANISM AND IMPLICATIONS

Field experiments conducted at the Hancock Agricultural Research Station during the 1987 growing season showed that preferential flow paths were the dominant flow pattern in the Central Sand Area of Wisconsin (CSAW). The observed preferential flow was different from other preferential flow patterns mentioned in the literature (e.g., "short circuiting" flow and "fingering" flow). This paper presents a detailed discussion of the mechanism of this preferential flow and its influence on groundwater contamination, soil solution sampling, and solute transport modeling. Four factors that will determine the occurrence of a funneled flow are: (A) conductivity of the upper finer layer, K; (B) slope of the inclined layer, sin (β); (C) retention potential of the upper finer layer, 2σ/r; and (D) ponding potential, ρ g L. © 1990.