2001 Fiscal Year Final Research Report Summary
Study on the mechanism of the riparian trees expansion in a gravel-bed river and an approach to that management
| Project/Area Number |
12650505
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
水工水理学
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| Research Institution | Gunma University |
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Principal Investigator |
SHIMIZU Yoshihiko Gunma University, Associate Professor, 工学部, 助教授 (70178995)
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| Co-Investigator(Kenkyū-buntansha) |
KOBATAKE Shigeki Gunma University, Professor, 工学部, 教授 (00027260)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Riparian trees / Gravel bed-river / Robinia pseudo-acacia / 2D-flow model / Critical tractive force / Instream vegetation / 一般化座標系平面流数値計算 / 動的樹林化 |
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| Research Abstract |
Recently riparian trees in the course of gravel bed-river have extremely increased and enlarged their covered-area over bars and flood plain. Such a situation brings about problems of river management for the environmental aspects as well as the safety of rivers against flood. In order to clarify such problems, we should get the knowledge about how the instream vegetation grow up and expand their covered zones in the gravel-bed river. In this study, the cause of the excessive growth of Robinia pseudo-acacia was examined in the segment-1 reach of Watarase River. Especially, from the investigation of the annual rings of tree, it was clear that some forests of Robinia pseudo-acacia in bars were formed right after of the main flood. We show that the floods cause change of generation of the trees and rapidly expansion by the germination from fallen trees makes the excessive growth of riverine trees. Based on the field study and numerical analysis with 2D- flow model, the critical tractive force to be an index of the scale of flood disturbance is evaluated and results show that the damage scale of the riparian trees depends on the size of the critical tractive force and bed-degradation.
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