2004 Fiscal Year Final Research Report Summary
Study on Salt Water Intrusion of Estuary in Compound Channel
| Project/Area Number |
14550517
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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 | Hachinohe National College of Technology |
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Principal Investigator |
FUJIWARA Hirokazu Hachinohe National College of Technology, Department of Civil and Environmental Engineering, Associate Professor, 建設環境工学科, 助教授 (70199389)
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| Co-Investigator(Kenkyū-buntansha) |
SUGITA Hisao Hachinohe National College of Technology, Department of Civil and Environmental Engineering, Associate Professor, 建設環境工学科, 助教授 (10280322)
YAGUCHI Junitchi Hachinohe National College of Technology, Department of Civil and Environmental Engineering, Professor, 建設環境工学科, 教授 (80342450)
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| Project Period (FY) |
2002 – 2004
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| Keywords | brackish lake / compound channel / salt water intrusion / Corbicula japonica / neural network / density current / horizontal mixing / field measurement |
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| Research Abstract |
In the regional development, a balance of development and preserving of natural resource should be considered. The precious natural environment has to be maintained. The Lake Ogawara in Aomori Prefecture is one of large brackish lake where the most dominant water organism for fishery is Corbicula japonica. Takase River connects the lake with the Pacific Ocean. The river is a tidal river with the compound channel. Filed measurement and laboratory experiments were carried out in order to understand mixing characteristics of river estuary in this research. Salinities of the lake were able to estimate from field data. The transverse mixing coefficients were obtained from these results using diffusion equation, and compared with those in compound channel. This result agreed with the conventional research. The mixing coefficients were related to the product density current parameter and cross-section of channel parameter. It was showed that the values of k_y/u_*h were related to the product β and d/D (k_y : transverse mixing coefficient, u_* : shear velocity, h : water depth, β : relative water level difference of fresh water and salt water, d : water depth of flood channel, D : water depth of main channel ). This result agreed with the values of k_y/u_*h required field measurement data. Therefore, it was found that Takase River estuary was influenced by compound channel from these results.
The water quality and the flow of the lake is very related to the habitation of the clams. The field observation of water quality was carried out for this lake in the period for three years from August 2002. From a viewpoint of water quality environment, egg-laying and hatching of them are performed on the north side of the lake, and they diffuse throughout the lake by the flow.
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