Construction and verification of a method for quantitative evaluation of sediment yield that induces debris-flow disasters

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K22595
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0603:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: National Research Institute for Earth Science and Disaster Prevention
• Principal Investigator: Akita Hiromi 国立研究開発法人防災科学技術研究所, 水・土砂防災研究部門, 特別研究員 (60880820)
• Project Period (FY): 2020-09-11 – 2022-03-31
• Keywords: 生産土砂 / 斜面崩壊 / 土石流災害 / 花崗岩類 / 堆積岩類 / LP地形データ / 差分解析 / 衛星画像

Outline of Final Research Achievements

This study examined sites with different geological features in Tamba City, Hyogo Prefecture and Hiroshima City, Hiro-shima Prefecture, where debris flow disasters were caused by heavy rainfall in August 2014. The sediment volume (V) of each landslide was calculated based on comparisons LiDAR-derived DEMs before and after the disaster. The α- and γ-values of the landslide volume estimation equation, i.e., V = αAγ, where A is landslide area, were also estimated. The results showed a negative correlation between the α- and γ-values, with the γ-value increasing as the ratio of the land-slide depth to the landslide area increased. Igneous rocks had larger α-values and smaller γ-values and sedimentary rocks had a wide range of α- and γ-values.

Free Research Field

砂防学

Academic Significance and Societal Importance of the Research Achievements

崩壊面積の情報のみを用いて、崩壊生産土砂量を早期かつ精度良く推定する手法があれば、緊迫した災害直後でも広域的な被害推定が可能になると考えられる。また、災害前には土石流の規模や危険度の推定に活用でき、災害後は行政機関が災害関連事業を進めるための砂防基本計画の検討にも寄与できると期待される。