地質境界が存在する斜面での地質構造や水文特性に着目した表層崩壊危険度評価手法の提案

抄録

In the Nachi River basin, the shallow landslides and the debris flows occurred by the heavy rainfall from Typhoon Talas in 2011. This basin is characterized by the existence of geological boundaries, which is considered to be one of main causes of the landslides. In this study, we conducted geophysical and hydrological surveys to make it clear. First, we conducted airborne electromagnetic survey. Second, the groundwater level was observed using the boreholes. The surveys were conducted on landslide occurred and not occurred slopes and the results were compared. Third, we conducted hydrological observation of the surface soil layer near the geological boundary using the tensiometers and the soil moisture meters. As a result, we have found that both the drainage characteristics and the distribution of resistivity were different on the two slopes. We have also found that geological boundaries affect hydrological behavior.