Foundamental Studies on Oxygen Reaeration at Hydraulic Structures in Nature-Oriented River Work
| Project/Area Number |
12460106
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Ehime University |
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Principal Investigator |
FUJIHARA Masayuki Ehime University, Agriculture, Professor, 農学部, 教授 (40253322)
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| Co-Investigator(Kenkyū-buntansha) |
KAINO Osamu Ehime University, Agriculture, Assistant Professors, 農学部, 講師 (30112254)
FUKUSHIMA Tadao Ehime University, Agriculture, Professor, 農学部, 教授 (90036319)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥6,300,000 (Direct Cost: ¥6,300,000)
Fiscal Year 2002: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | reaeration / boulder-paved fish slope / hydraulic structures in rivers / self-purification in rivers / weirs / 落差工 / 河川整備 / 多自然型河川工法 / 魚道 / 数値シミュレーション |
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| Research Abstract |
The potential contribution of hydraulic structures through air entrainment to the improvement of oxygen deficiencies in rivers has been recognized in the past and several papers reporting oxygen uptake at drop weirs. However it has not been clear that predictive equations proposed in those papers are applicable to a variety of design situations.
The objective of the research is to evaluate the oxygen transfer at relatively complicated hydraulic structures through comparing to simple drog weirs.
The field observations were done at three weirs and two boulder-paved fish slopes. Two of the weirs consist of slope with drops at both upstream and downstream ends. The remaining of the weirs is a boulder-paved sloping weir. From the results obtained at these weirs, it is concluded that aeration performance during flowing on the slop is less than at the drop but it would be more if slop was paved by natural boulders. This is due to the hydraulic jump, splash and turbulence generated by bottom unevenness, which improve oxygen transfer through air water interface.
To confirm the above results., field observations were carried out at two boulder-paved fish slopes. The results showed that the reaeration performance at the fish slopes were greater than those at drop which has same drop height of the fish slopes. Moreover it was cleared that the oxygen transfer efficiency depends on the relashionship between the interval of boulders and flow distance up to the point where jet flow emerges. If the interval between boulders is greater than the distance in which subcritical flow changes into supercritical flow, hydraulic jump surely occurs. Hydraulic jump greatly contributes oxygen reaeration especially when discharge is not so large.
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Report
(4 results)
Research Products
(2 results)
