Abstract
An arrangement of fine-grained soil overlying coarse grained soil along a sloping contact can, under appropriate circumstances, hal infiltrating water away from the coarser material. Such an arrangement is called a capillary barrier. The water halted by a capillary barrier flows downward above the contact. This type of flow is named a funneled flow. The amount of funneled flow increases in the downward direction as additional infiltration is halted by the barrier. Sufficiently far downward, the funneled flow wets the contact to the point that an amount of water equal to the infiltration penetrates vertically into the coarse soil mostly in the form of a fingering flow. The lateral distance at such a point is defined as the diversion capacity of an inclined capillary barrier.
Diversion capacities of the inclined capillary barriers were measured experimentally by using a rain fall simulator under which one of two types of transparent Hele-Shaw models, a small model or a large model, filled with a Hyojun sand layer over a coarse glass beads layer was placed. Since both of the unsaturated funneled flow model proposed by Ross and the saturated funneled flow model proposed by Kung are two dimensional models, they were modified into three dimensional models by using a catchment factor. Soil physical parameters which depend on the bulk densities of materials were corrected by using non-similar media scaling technique. These modifications significantly improved the ability of predictions of the measured diversion capacities.
