2018 Fiscal Year Final Research Report
Mechanisms and risk evaluation of meltwater-induced landslides on forest-covered slopes during strong wind
| Project/Area Number |
16H03151
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Natural disaster / Disaster prevention science
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
平島 寛行 国立研究開発法人防災科学技術研究所, 雪氷防災研究部門, 主任研究員 (00425513)
松四 雄騎 京都大学, 防災研究所, 准教授 (90596438)
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| Research Collaborator |
OKAMOTO Takashi
KAMIISHI Isao
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Keywords | 積雪地帯 / 強風時の融雪 / 積雪層内水移動 / 積雪荷重 / 浸透能 / 土壌水分 / 間隙水圧 / 地すべり |
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| Outline of Final Research Achievements |
To evaluate the landslide hazard caused by meltwater on a forested slope during strong wind, we carried out field observations and in-situ tests in a heavy snowfall area in addition to laboratory experiments and numerical simulations. As a result of the laboratory experiments and field observations, turbulent flow generated near the canopy in a relatively sparse forest stand can cause a large amount of snow melting. Because the meltwater infiltrates the snowpack and then forms complex water pathways, meltwater flows out locally, and we reproduced this phenomenon by numerical models. Based on long-term results of deep pore-water pressure in snow-covered conditions, the magnitude of the pore-water pressure increase tends to be relatively suppressed because of the seasonal decrease in the permeability of the surface soils and a decrease in the volume of the vadose zone. These research results should help improve the accuracy of landslide risk evaluation in heavy snowfall areas.
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| Free Research Field |
傾斜地保全学
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| Academic Significance and Societal Importance of the Research Achievements |
気温による融雪予測は研究蓄積も数多くある。一方、積雪層に雨が降る場合は雨の観測が容易なうえに融雪熱量も計算しやすい。ところが、風による融雪は発生頻度が少ないため、他の融雪要因の研究に比べ大幅に遅れている。また、前二者については、「気温上昇=融雪促進」、「降雨=災害多発」というイメージがあることから、災害に対する注意を喚起しやすい。ところが、風による融雪については強風で急激に雪が融けることが、必ずしも流域内の住民に共有されていない。本研究で強風時の融雪現象が明らかとなり、地すべり発生危険度評価の精度を高めることができた。したがって積雪地帯における地域住民の安心と安全の確保に寄与できる。
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