2020 Fiscal Year Final Research Report
Study on the mechanism of fine sediment deposition in tidal zone and its application to new management to improve disaster safety
| Project/Area Number |
18K04371
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 22040:Hydroengineering-related
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| Research Institution | Maebashi Institute of Technology |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
大本 照憲 熊本大学, 大学院先端科学研究部(工), 教授 (30150494)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 感潮域 / 複断面河道 / 二次流 / 密度流 |
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| Outline of Final Research Achievements |
A tidal river is a mixture of saltwater and freshwater, which makes it highly productive and has a very rich ecosystem. Therefore, it is very important to understand tidal rivers in order to develop a well-balanced region.
In this study, we aimed to clarify the characteristics of the flow and sediment deposition mechanisms in a compound channel of a tidal river.
As a result, field observations during high tide showed that secondary flow cells occurred in the fairway From the numerical analysis, it was found that the secondary flow at the lower tide was caused by salinity, while salinity and water temperature had little effect on the occurrence of small secondary flow cells at the upper tide.
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| Free Research Field |
水工学
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| Academic Significance and Societal Importance of the Research Achievements |
これまでの研究から，流れ方向主流速の空間分布と二次流構造は微細土砂の横断方向への堆積厚さに関与していることがわかっていた．流動機構を解明することは，物質輸送，底質形成，水質環境などの研究で，また船舶の航行や漁業分野では，効率的な移動や停泊において重要である．
本研究において，物質輸送の一部に横断面内の二次流構造が寄与していることを見出した．さらに流下方向の土砂輸送は，最強流時に多いこと，上層と下層で濃度が異なっていることなども明らかになった．このように本研究を通して感潮域の往復流の新たな作用が判明し，水工学のみならず地盤工学や生物学，水産学等への応用も考えられる．
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