| Project/Area Number |
18K04362
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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 | Gunma University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2020)
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| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2020: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2019: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2018: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 複列砂州 / 低水路蛇行 / 単列化 / 水衝部 / 河岸侵食 / 河道内樹林化 / 砂州の樹林化 / 単列砂州化 / 蛇行流路 / 砂州の固定化 / 低水路 / 流路形態 / 河床変動 / 流路変動 / 移動床水理 / 河道管理 |
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| Outline of Final Research Achievements |
The purpose of this study was to elucidate the factors that cause the degeneration of double-row bar bed rivers and its mechanism. We focused on appearance of a single meandering channel that often causes riverbank erosion. As a result, it was clarified that one of the riverbank sandbars in the double-row sandbar expanded and integrated with the central sandbar, resulting in asymmetry of the planar shape and the progress of single meandering channel formation. In addition, the effects of bank erosion and of vegetation invasion were extracted as external conditions to cause remarkable development of a single meandering channel. In the former case, bed aggradation due to the lateral supply of sediment and in the latter case, the forestation of sandbars which causes the fixation of sandbars, both are important roles to promote a single meandering channel. Based on these results, we presented useful findings on the river channel management in the double-row sandbar channel.
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| Academic Significance and Societal Importance of the Research Achievements |
複列砂州を伴う河道では，洪水時の流路変動が活発で川の自律的な変化が維持できる河道とされている．しかしながら，近年こうした河道特性が崩れ，砂州の固定化と河道内樹林化，単列蛇行流形成がもたらす水衝部固定など，河道のダイナミズムが消失している．こうした傾向は複列砂州維持の自律性を崩し，非可逆的な単列化傾向となって河道の二極化を生むことから治水的にも河川環境的にも好ましくなく，複列砂州の維持・自律的回復の手立てが喫緊の河道管理の課題である．本研究は，複列砂州河川の河相変質を生む要因とその機構についての理解を進め，単列化を強調する条件を明らかにして河道管理について有用な知見を提示するものである．
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