[M-IS11] Mountain Science

[MIS11-P12] Changes of sediment volume on the northeast slope of Mt. Shakushi

*Serina Takaki¹, Chiyuki Narama² (1.Graduate School of Science and Technology, Niigata Univ., 2.Niigata Univ.)

Keywords:Snow patch, Debris flow, Rock slope failure, Northern Japanese Alps

On August 23, 2013, a debris flow occurred on the northeastern slope of Mt. Shakushi. The debris flow was caused by torrential rainfall of 300 mm cumulative and 55 mm per hour. The 2013 debris flow on the northeastern slope of Mt. Shakushi was reported to have been caused by debris flow from accumulated sediment on the slope (Jogasaki et al., 2014). Sediment production from the surrounding bedrock slopes continues to occur on the northeastern slope of Mt. Shakushi, and there is a risk of another debris flow. In this study, the amount of sediment deposited in valley strips V1 and V2 on the northeast slope of Mt. Shakushi was determined by differential analysis in ArcGIS Pro. The results of the differential analysis indicated that a large collapse was observed on the bedrock slope upstream of V1, suggesting that the rapid increase in sediment volume in 2017 was associated with the collapse of the bedrock slope. In the future, we plan to determine the sediment volume at the foot of the site and evaluate it together with the sediment volume in the valley.