雨水流出現象における初期貯留量について ―樹木による降雨遮断―

Abstract

This paper describes the interception mechanism of rainfall by trees which occurs firstin a runoff process. The results obtained by experiments and the theoretical considera-tions are as follows:1) The relation between amounts of the water storage on a tree, that is, interception, and the leaves of tree is shown quantitatively to be linear for each kind of trees.2) The amount of water storage on a tree is constant for a constant intensity ofrainfall, and draws exponentially to the maximum value, S~, for larger intensity ofrainfall.3) In the unsteady state of the interception process, the storage equation of rain-water on a tree during the period of rainfall is shown as equation (8) by using theequivalent area of tree, At, which is concerned directly in the process, and the maximumwater storage, Sm.4) In the decreasing state of the water storage on trees after rain ceasing, the storagedecreases following to equation (8) during the period of several minutes after ceasing, exponentially for the period later than about 30 minutes, and during the period fromseveral to 30 minutes there exist both the decreasing processes of stem flow and of waterdrop on leaves.