荒川流出試験地の流域特性について

Abstract

In order to observe the hydrological phenomena with respect to the runoff processand the water balance in a small mountainous watershed, an experimental area wasarranged in 1966 in the River Ara, a tributary of the River Yasu which flows into LakeBiwa. This paper describes the characteristics of vegetation, geology, hydrogeology, geomorphology and so on of the basin, in relation to the runoff process of rain-wateror the field of motion of rain-water. It was found by field observation, laboratory testand topographical analysis that (1) the basin is densely covered with needle- and broad-leaved trees, (2) the surface stratum is the well-graded sand, 0. 2 0. 4 mm in 10% grainsize by weight and 1-2mm in 50%, and its average depth is beween 1 and 2 m, whichresults from weathering the bed rock, granite, (3) the topographical features followsvery well to the laws of bifurcation of streams, length of streams of each and area ofsub-basin of each order.