2017 年 70 巻 1 号 p. 31-37
This study conducted a detailed analysis of the failure process and sediment yield of a freeze-thaw induced landslide. As most of the slopes where freeze-thaw failure occurs are located in inaccessible areas, in mountainous environments and under severe meteorological conditions, a safe and high-precision measurement method has not been established. The study site is a slope along the Yotagiri River. In order to obtain high-density and high-precision data, terrestrial laser scanning was applied. Between 2010 and 2013, surveys were conducted four times before freezing in November and December, and three times after thawing in June of the following year. In all, seven surveys were conducted. The landslide volumes were calculated using DEMs (Digital Elevation Models), by subtraction within the landslide-affected area. By the analysis of erosion and deposition of the slope over time, it became clear that a large amount of sediment from the freeze-thaw failure has been supplied to the stream. The analysis also revealed the erosion volume per unit area, estimated at 42,100 m3/km3/year in the study area.
