2019 Fiscal Year Final Research Report
Challenging research on active allocation design of floodplain forest by scientific approach
| Project/Area Number |
18K18919
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 25:Social systems engineering, safety engineering, disaster prevention engineering, and related fields
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| Research Institution | Kyoto University |
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Principal Investigator |
Sanjou Michio 京都大学, 工学研究科, 准教授 (80362458)
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| Project Period (FY) |
2018-06-29 – 2020-03-31
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| Keywords | 水害防備林 / エネルギー減衰 / 洪水流 |
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| Outline of Final Research Achievements |
A flood protection forest is a conventional river-management measure that can fit well into the natural environment. This study focused on single-line tree models placed laterally and multi-line tree models. Horizontal and Vertical particle image velocimetry (PIV) measuements and drag force measurements were conducted in a laboratory flume to examine the reduction efficiency of mean kinetic energy due to the tree members and bottom friction properties.The results showed that the flow structure is related closely to a wake phenomenon
for sparsely arranged trees, whereas it is similar to a jet for a dense arrangement.Furthermore, a semi-theoretical formula was developed that was found reasonable in predicting energy reduction efficiency. A downstream bank has an important role to control a depth of oncoming stream, and it implies suppression of the pressure gradient in the streamwise direction. It induces more effective reduction of velocity through the forest.
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| Free Research Field |
水工水理学
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| Academic Significance and Societal Importance of the Research Achievements |
自然繁茂している河畔林の間伐や再植林により，比較的低コストで広範囲の流域をカバーできる．研究成果は，効果的な氾濫減衰のための防備林デザインを構築するもので，水防災・水減災・強靭なまちづくり（実用研究）に貢献し，水工災害学，河川工学に関連する幅広い分野において大きな意義をもつ．特に水路実験の高精度実測データは，防備林周辺の河床変動や浸食機構の解明をはじめとする河川力学の基礎学理（基礎研究）の重要課題の突破口としても期待され，学術的意義も大きいと確信する．さらに人工構造物と比べて防備林は整備しやすいため，本成果は伝統的水防対策の再考を促すきっかけとなるとともに全国的に広く波及すると考える．
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