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論文(リポジトリ) |
論文(リポジトリ)
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古谷, 元 ; 末峯, 章 ; 丸井, 英明 ; 佐藤, 修 ; 原, 龍一 ; 岡本, 敦
概要:
We carried out investigation of soil temperature at one-meter depth and water quality (water temperature and electric conductivity) to make clear relationship between slope failure and groundwater flow at source area of debris flow in the
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Tobinosu-dani-A stream, Zentoku, Tokushima, Japan. Furthermore, we investigated water temperature and electric conductivity of springs, at Tobinosu-dani-C stream, boreholes and underflow at Z6 block of Zentoku landslide to grasp the origin of groundwater. The results of our investigations are as follow. The groundwater flows at the source area of Tobinosu-dani-A stream are under flow type, which is flowing from outside of basin. Direction of these flows are Northeast to Southwest, which may be controlled to relative high permeability structure in the bedrock. The slope failure at source area of debris flow in this stream is caused by underflow from North to South.
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| 2.
論文(リポジトリ) |
論文(リポジトリ)
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古谷, 元 ; 末峯, 章 ; 小山内, 信智 ; 原, 龍一 ; 佐藤, 修 ; 小松原, 岳史
概要:
Many debris flows caused by heavy rainfall have occurred at mountains in crystalline schist area, Shikoku Island, Southwestern Japan. The typical movement form of debris flow caused by heavy rainfall in mountainous area is
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fluidizing of soil mass from source area of debris flow to down slope (Stream). The debris flow at Tobinosu-dani stream in Zentoku, Nishiiyayama village on 29 June 1999 is this type of movement form. Therefore, it is important to make clear about occurrence mechanism of slope failures at source area of debris flow. Then, we carried out investigations of soil temperature at one-meter depth, water temperature and electric conductivity of springs and boreholes at the source area in the Tobinosu-dani stream and the Zentoku landslide. The results of our investigations are as follow. 1) There are two types of groundwater flows at the source areas of debris flows in the Tobinosu-dani stream that cause slope failure. One type is underflow changed by groundwater flow in deep layers with low value of electric conductivity. The other type is fissure water like groundwater vein-streams from deep layer with one digit higher value of electric conductivity than the underflow. 2) It is presumed that different of value of electric conductivity between underflow and fissure water is based on the different storage time (groundwater pass). Depth of the fissure water supply, especially, is corresponding to the approximate depth of the sliding surface (or bed rock) in the Zentoku landslide.
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