2023 Fiscal Year Final Research Report
Development of a numerical simulator to prevent and mitigate sediment and flood damage
| Project/Area Number |
21H01597
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 25030:Disaster prevention engineering-related
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| Research Institution | Ritsumeikan University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
権田 豊 新潟大学, 自然科学系, 教授 (10303116)
内田 太郎 筑波大学, 生命環境系, 教授 (60370780)
藤本 将光 立命館大学, 理工学部, 准教授 (60511508)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 土砂・洪水氾濫 / 土石流 / 掃流状集合流動 / 浮遊土砂 / 堆積速度 / 細粒土砂 |
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| Outline of Final Research Achievements |
Several numerical simulation models were developed for debris flow, bed load and suspended load regions, focusing on the behavior of fine sediment. Reproduction calculations were performed for two watersheds with clear differences in the grain size of produced sediment and the grain size of riverbed materials, and the effects of the grain size of produced sediment and the handling of fine sediment on the numerical calculation results were clarified. In addition, a new sediment transport model was developed that covers everything from debris flows to bed load and suspended sediment by incorporating a model of the phase shift of fine sediment in debris flows and a suspended sediment model in steeply gradient rivers based on a unified model of inertial debris flows. The deposition rate of mixed sand and gravel at gradient change points was measured in flume experiments, and the applicability of the deposition rate formula used in conventional numerical calculations was examined.
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| Free Research Field |
砂防工学、河川工学
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| Academic Significance and Societal Importance of the Research Achievements |
土石流領域から掃流砂・浮遊砂領域までに適用可能な流砂モデルを開発し、複数の実領域への適用を通じてその妥当性を検証してきた。まだまだ未解明な点は多いものの、勾配変化点で実際には生じない顕著な土砂堆積が計算されるという課題は解決できたと考えている。また、細粒分を用いた水路実験を行い、粒径が堆積速度に大きな影響を与えることを明確にしたことは、これまで堆積速度係数の設定に問題があった部分を解消できる可能性が高いと考えている。実験ケース数を増やし、粒径の範囲等をさらに広げていくことで、より実用性の高い流砂・河床変動モデルの確立につながるものと期待している。
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