Development of Soil Erosion Model and Application of Debris-Flow Model for Sediment Disaster Mitigation in Forested Watersheds

2023 Fiscal Year Final Research Report

• Project/Area Number: 19KK0392
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research (A))
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 40:Forestry and forest products science, applied aquatic science, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Hotta Norifumi 東京大学, 大学院農学生命科学研究科(農学部), 准教授 (00323478)
• Project Period (FY): 2020 – 2023
• Keywords: 土壌侵食モデル / GeoWEPP / 土砂流出 / 土石流数値計算 / 微細土砂

Outline of Final Research Achievements

This study improved a soil erosion model and a debris-flow model for the mitigation of sediment disasters, including driftwood disasters. The soil erosion model reproduced long-term sediment discharge from forested watersheds by appropriately describing sediment dynamics on slopes and within channel sections, respectively. The debris-flow model, after analyzing field data and laboratory tests focusing on the behavior of debris flows on debris-flow fans, successfully reproduced the deposition patterns on these fans.

Free Research Field

砂防工学

Academic Significance and Societal Importance of the Research Achievements

森林における長期的な土砂流出量が土壌侵食モデルで再現することで，森林管理の影響を数十年スケールで検討することが可能になる．一般に，日本における土砂流出は侵食などの面的な土砂生産より，崩壊や土石流などの局所的な土砂生産源が支配的であると考えられているが，土石流モデルによって土石流の堆積範囲を正確に予測することで，森林流域からの土砂流出量を，撹乱を考慮しつつ予測することが可能になる．