Development of new indicators and their measurement techniques which enable a prediction of glide avalanche release

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K18918
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 25:Social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Niigata University
• Principal Investigator: Matsumoto Takane 新潟大学, 災害・復興科学研究所, 特任准教授 (20374209)
• Co-Investigator(Kenkyū-buntansha): 河島 克久 新潟大学, 災害・復興科学研究所, 教授 (40377205)
• Project Period (FY): 2018-06-29 – 2021-03-31
• Keywords: 全層雪崩 / グライド / 積雪の性状変化 / 積雪底部 / 誘電式含水率計 / 電気伝導度 / 低灌木 / 倒伏過程

Outline of Final Research Achievements

In order to clarify the relationship between release of a glide avalanche and changes in physical properties of a snowpack in the starting zone, various observations were carried out on a steep slope in Oshirakawa, Uonuma City, Niigata. During the period between the onset of snow glide and the avalanche release in the winter of 2020/21, values measured with dielectric soil moisture probes which were installed into the lowest layer of the snowpack showed a sudden decrease followed by a large increase. In addition, specific electric conductivity of water in a small stream from the starting zone showed remarkable increase several hours before the avalanche release. These changes can be regarded as precursors of avalanche release. On the other hand, results of observations on tipping process of deciduous shrubs on the slope indicate that weather conditions in early winter also have a significant influence on snow glide and avalanche release.

Free Research Field

雪氷水文学

Academic Significance and Societal Importance of the Research Achievements

全層雪崩発生の直前予測を行なうには、これまではグライドメーターを設置して積雪グライド速度の連続的な計測をするのが唯一の方法とされてきた。本研究の成果からは、誘電式含水率計を用いた積雪最下層部のモニタリングや、斜面下方の水流の電気伝導度計測などを併用することで、より確実な全層雪崩発生の直前予測が可能となることが示唆される。また、斜面上の植生の倒伏状態が全層雪崩の発生に及ぼす影響が大きいという本研究の知見は、雪崩発生直前の時期だけでなく、初冬の気象条件をも注視することが、雪崩発生危険度を評価する上で必要になることを明らかにした。