We analyzed characteristics manifested by shallow landslides using SHALSTAB and LiDAR 1-m DEM for the intensive shallow landslide event that occurred in the Tsurugi-kawa drainage basin, Hofu City, Yamaguchi Prefecture in 2009. Based on the results, we created a risk assessment map to evaluate surface landslides in this basin. Consequently, we could quantitatively extract and visualize shallow landslide risk areas that had a tendency to have a high-risk probability based on their qualitative geomorphological characteristics. Using SHALSTAB and LiDAR 1-m DEM, we found that it was possible to evaluate relative risk by least assumptions (parameters) without conventional data that were typically utilized for studying shallow landslide processes such as the spatial distribution of soil depth and hydraulic conductivity. However, basic topographic parameters such as slope and basin area and hydraulic conductivity values that were measured in the laboratory considerably affect risk evaluation, but the process of obtaining these values at each shallow landslide area was not established. For example, hydraulic conductivity values measured in the laboratory proved unsuitable to be used in a drainage scale numerical model such as SHALSTAB. This result clearly indicates that spatially expanding the measurement results of various physical property tests in the laboratory is difficult. Conversely, this indicates the importance of research that is focused on using numerical models to estimate values such as watershed characteristics that cannot be actually measured. However, estimating soil depth and hydraulic conductivity, whose spatial distributions are difficult to grasp, may be possible by a numerical model such as SHALSTAB.

豪雨

危険度評価

LiDAR数値標高モデル（DEM）

地形計測

地形プロセス学

チイキガク ケンキュウ