A new method by exploring responses of mountain slopes to river incision for predicting potential landslide sites for hazard mitigation: A case of Shirakami-Sanchi, Japan

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K20893
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science; Forest science
• Research Institution: Hirosaki University
• Principal Investigator: Tsou Ching-Ying 弘前大学, 農学生命科学部, 助教 (40750055)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: landslide / river incision / Shirakami-Sanchi

Outline of Final Research Achievements

Mt. Shirakami shows a typical fluvial landscape where many landslides are distributed. Field geological and geomorphological surveys, mapping of landslides using aerial photos and 1 m LiDAR DEM were conducted. At the Okawa landslide, comparison of the topography of 2017 and 2008 suggests horizontal displacements range from 0.1-9.7 m. At the landslide body of the northern part the computed vectors show a southward movement. The longitudinal displacement for a flat, terrace-like topography within the landslide body of the southern part was computed of ~7 m. Active displacements were constrained at the secondary and side scarps of 3-9 m and the edges of toes of 2-8 m, where the retreating movements are identified relating to the river erosion. Similar phenomena were demonstrated at the Sansukezawa landslide. Study on the Juniko landslide suggests its occurrence may be divided into the northern and southern parts associated with flowing and slump mechanism, respectively.

Free Research Field

砂防学

Academic Significance and Societal Importance of the Research Achievements

気候変動や地震により大規模な地すべり・崩壊が多発すれば、土砂災害とともに森林生態系も大きな影響をうけることが懸念される。本研究は、地すべり斜面の変動に関する定量的なデータが少ない白神山地において、詳細な地形データに基づく地すべり発生機構や斜面動態の計測に基づき解析を行った。山岳地の地形発達において、河川プロセスがマスムーブメントの発生場に対し重要な役割を働いていることを明らかにすることによって、より詳細かつ実態的な地すべり発生機構の解明に資するものである。本研究の成果も環境保全に資するところもあると考える。