Technical development for hillslope conservation based on the processes of soil production and runoff

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14001
• 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
• Principal Investigator: Watakabe Takuma 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 (10883663)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 土層生成 / 土砂流出 / 表層崩壊 / 山地保全 / 宇宙線生成核種 / 航空レーザー測量

Outline of Final Research Achievements

In this study, I predicted long-term soil layer development in the head-water basin underlain by granite bedrock using a simulation of soil production, transport, and removal. The soil production rate is quantified using cosmogenic beryllium-10 and the sediment runoff is monitored by direct observation. Soil particles accumulate on concave part of the hillslope. The soil layer develops thicker over time in the steep parts of the hillslope with the high risk of shallow landslide initiation. In gentle hillslope with persistent stream flow, thickness of the soil layer is kept thin due to sediment transport by water flow. Sediment supply to downstream areas will likely decrease over long term when the ability of sediment transport falls due to decrease in the frequency of heavy rain or burial of the stream bed.

Free Research Field

自然地理学

Academic Significance and Societal Importance of the Research Achievements

土層の生成量と降雨時に流出する土砂量という時間スケールの違う地形プロセスを統合し、山地源流域の土層発達過程を予測した点において、学術的意義がある。本研究で得られた成果には改善の余地は残されているものの、長期的な土砂生産量を予測できるため、水・土砂管理施設の維持的な管理に資する情報を提供できる。