2018 Fiscal Year Annual Research Report
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
| Project/Area Number |
16K20893
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| Research Institution | Hirosaki University |
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Principal Investigator |
鄒 青穎 弘前大学, 農学生命科学部, 助教 (40750055)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | landslide / river incision / Shirakami-Sanchi |
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| Outline of Annual Research Achievements |
Mt. Shirakami of Japan shows a typical fluvial landscape comprising paleosurface remnants with moderate relief at higher elevations and incised V-shaped inner gorges below them, made by the recession of knickpoints. We made field geological and geomorphological surveys, mapping of landslides using aerial photos and airborne LiDAR-derived DEM of 1-m resolution. At the Okawa landslide, we constructed DSM from UAV imagery obtained on 6 November 2017. Then, the DSM was used to compare to the LiDAR DEM acquired on 22 October 2008 to constrain the landslide magnitude and direction of the displacement vectors using CIAS (Kaab and Vollmer, 2000). Results were also compared with longitudinal profiles collected by a hand-held laser-ranger finder. The computed horizontal displacements range from 0.1-9.7 m with a standard deviation of 1.8 m. At the landslide body of the northern landslide the computed vectors suggest a southward movement. The longitudinal displacement for a flat, terrace-like topography within the landslide body of the southern landslide was computed of ~7 m that is represented as compared with the filed measurement. Active displacements were generally 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. Similar phenomena were demonstrated at the Sansukezawa landslide, where the analysis of tree ring width was applied to constrain the timing of landslide occurrence. The findings indicate the onset of landslide since 1950s and the secondary landslide at 1960s, 1975s, 1990s, and 2000s.
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Research Products
(3 results)
