愛知県小原村周辺の山崩れについて (II) -斜面における土壌水と基岩の風化について-

Abstract

The behaviour of the soil moisture in the topsoil of the hillslope is analyzed on the basis ofthe field observation using tensiometers and so on. The soil is usually dry at the ridge parts andwet at the hollows, which represent the topographic effect on the soil moisture, and the soil re-peats the wetting and drying cycle in the shallow horizon and remains wet in the deep horizon, which represent the effect of the soil depth on it.It is also revealed that two modes of the circulation of infiltrating water take place in the di-fferent soil horizons, the one a circulation including evapotranspiration flux and the other in-cluding steady percolation and throughflow. The former circulation will promote the wettingand drying weathering, and the latter will be favorable for the chemical weathering. Thedifference of the subsurface structure between convex and concave slopes as shown in Fig. 1may be explained by these effects.