The role of vertical pipes in the formation of saturated zones in a hillslope
1993
Wang, D. (Tokyo Univ. of Agriculture and Technology, Fuchu (Japan). Faculty of Agriculture) | Kubota, J. | Tsukamoto, Y.
Vertical pipes with 1-2cm diameters were found in high density within surface soil layers on a forested slope of Tama-hill. The total length of the vertical pipes was 7-8m in the two pits (1m x 1m x 2.2m). The role of the vertical pipes in the formation of saturated zones is discussed with the results of soil column experiments and field experiments. The column experiments, using a stratified two-layer formation which consisted of a permeable upper layer and an impermeable lower layer with vertical pipes demonstrated a rapid flow through the pipes when saturated zones in the upper layer were formed locally around the entrances of the pipes. With the field measurements of water levels and pressure heads on the slope under natural and artificial storms, it was found that saturated zones in the lower layer were formed locally at various spots by rapid flows though vertical pipes after the bottom of the top soil was saturated. On the basis of these results, the authors present a conceptual model of saturated spots, which are formed locally by a rapid flow through vertical pipes in the lower layer, developing into continuous saturated zones in the slope
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