1993 Fiscal Year Final Research Report Summary
Study on Hydraulics of Rivers with Vegetation
| Project/Area Number |
04302043
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Hydraulic engineering
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
IKEDA Shunsuke Tokyo Institute of Technology Dept.Civil Eng., Professor, 工学部, 教授 (60016590)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Yasuharu Hokkaido Development Bureau Civil Eng.Research Institute, 開発土木研究所, 副研究室長
TSUJIMOTO Tetsuro Kanazawa University Dept.Civil Eng., Associate Professor, 工学部, 助教授 (20115885)
SUNADA Kengo Yamanashi University Dept.Civil Eng., Associate Professor, 工学部, 助教授 (20020480)
SHIMIZU Yoshihiko Gunma University Dept.Civil Eng., Research Associate, 工学部, 助手 (70178995)
ISHIKAWA Tadaharu Tokyo Institute of Technology, Dept.Environ, Physics & Eng., 大学院・総合理工学研究科, 教授 (50159696)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Flow with vegetation / Turbulent flow / River hydraulics / Honami / Sediment transport / River morphology / Growth of plants in rivers / Horizontal mixing |
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| Research Abstract |
1. Field survey of vegetation in rivers : The method of field survey of vegetation in flood plain of rivers has been established where the important to survey the micro-undulation of flood plain with observation of plants is emphasized. The field survey has been conducted in the river Tedori, and the characteristics of vegetation in flood plain of fluvial-fan rivers has been clarified. In Hokkaido, the destroyed trees in flood plains due to the flood (August 1992) has been minutely investigated in the Mukawa river. Furhermore, the growth process of low-trees around shore-line of lakes has been observed, and it has been attempted to predict the annual change of vegetation.
2. Flow over vegetation : Particularly, the flow over flexible vegetation has been focused on. The organized vortices near the boundary of the begetation layr has been investigated by film analyzing technique and MASCON model. On the other hand, instability of a closed system of deformation of plant and flow over vegetation with wavy boundary has been analyzed to explain a formation of honami.
3. Flow and sediment transport in flow with vegetation : Flow with vegetation zone is characterized by horizontal organized vortices. The transverse profile of velocity has been formulated and then the instability of such a horizontal shear flow has been analyzed to explain the organized motion. The induced low-frequency fluctuation affects even bed-load motion. To apply non-equilibrium transport law to alternating transverse bed-load transport has deduced the net transport of bed-load in the transverse direction which forms a sand ridge and a longitudinal stripe of fine sand near the vegetation zone.
4. Vegetation and sediment balance in river system : A new synthetic model to predict state of sedimentation in a whole mountainous river system, where pseudo channel network has been created from DEM.The model is applied to the small basin to demonstrate the high potential of the proposed model.
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