Pore-air pressure measurement in mountainous slope and its role on rainfall runoff process

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K19963
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Forest Research and Management Organization
• Principal Investigator: Iwagami Sho 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 (70612729)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 山地源流域 / 降雨流出プロセス / 間隙空気 / 土壌水 / 基岩地下水

Outline of Final Research Achievements

In the present study, we could successfully show that pore-air pressure is not negligible in the field measurement. It is shown that our handmade measurement system was useful for measuring the pore-air pressure in the soil layer, and also the measurement of inner pressure of the borehole was useful for evaluating the pre-air pressure in the bedrock layer.
Various rainfall amounts of rainstorm events accompanied with pore-air pressure rising were observed. By sorting the relationship between rainfall parameters and the peak discharge of rainstorm events by pore-air pressure response, it was revealed that the pore-air pressure response has influence on peak discharge. Especially the pore-air pressure response at the shallow bedrock groundwater will make influence on peak discharge.

Free Research Field

水文学

Academic Significance and Societal Importance of the Research Achievements

降雨流出プロセスにおいて，斜面内の間隙空気の挙動については主に室内実験において流出現象との関連が指摘されているものの，現地観測によりそのプロセスを示した例は未だほとんど無いと言える．本研究では山地斜面における間隙空気の観測手法について検討し，土層内・基岩層内それぞれにおける間隙空気圧の観測手法の有用性について示すことができた．本研究で得られた斜面内における間隙空気の挙動の実態や流出に影響を及ぼす条件等は新たな知見であるとともに，これらの結果は洪水発生や斜面崩壊とも関連し，災害予測において新しい提言へとつながる可能性がある．