Effects of preferential water flow in snow layers on landslide activity

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14562
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17030:Human geosciences-related
• Research Institution: Forest Research and Management Organization (2021-2023); University of Tsukuba (2020)
• Principal Investigator: Osawa Hikaru 国立研究開発法人森林研究・整備機構, 森林総合研究所, 主任研究員 等 (70839703)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 融雪 / 融雪地すべり / 選択的な水移動 / 側方流

Outline of Final Research Achievements

To clarify the water movement process in the snow layer, aerial photography by a drone was used to investigate the water flow path below the snow surface, a dye water tracer test was conducted on a sloped snowpack and a two-dimensional water movement analysis was conducted to reproduce the results. Aerial photography revealed that linear snow concavities of different scales were developed on the sloped snow surface toward the valley floor depression, and traces of water movement were observed. The results of tracer tests with different slopes and topography showed that in all experiments, the water movement generated on the snow surface on the slopes was predominant in the direction of the maximum slope inclination rather than in the vertical direction, and that the water supply to the ground surface was concentrated in the concave topography. Furthermore, water movement analysis reproduced the experimental preferential infiltration pathways.

Free Research Field

斜面水文学

Academic Significance and Societal Importance of the Research Achievements

本成果は、雪面で発生した水分が積雪層内を通り地表面へ到達し、積雪底面において水分の再配分を行う過程を明らかにすることから、融雪に起因する地すべり・斜面崩壊および融雪洪水といった融雪土砂災害全般の発生メカニズムへ寄与し、それらの予測手法や、効果的な地表水排水などの対策手法の立案において防・減災へと貢献する成果である。