1998 Fiscal Year Final Research Report Summary
Study on Water Exchange between Osaka Bay and Pacific Ocean
| Project/Area Number |
09650565
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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 | Osaka University |
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Principal Investigator |
NAKATSUJI Keiji Graduate School of Engineering Professor, 大学院・工学研究科, 教授 (10029324)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Tateki Kyoto University Graduate School of Agriculture Associate Professor, 大学院・農学研究科, 助教授 (30243075)
ONO Masanobu Graduate School of Engineering Assistant Professor, 大学院・工学研究科, 講師 (80214188)
DEGUCHI Ichiro Graduate School of Engineering Professor, 大学院・工学研究科, 教授 (00029323)
KAWASAKI Koji Graduate School of Engineering Research Associate, 大学院・工学研究科, 助手 (20304024)
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| Project Period (FY) |
1997 – 1998
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| Keywords | nutrient balance / water exchange / field survey / residual current system / baroclinic flow / numerical experiment |
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| Research Abstract |
According to the field survey conducted in Ki-i Channel in summer of 1995, its results indicated that lots of nutrients such as nitrogen (N) and phosphorus (P) of Pacific Ocean intrudes into Osaka Bay.Their volume surprisingly corresponds to total value discharged from coastal land area.One of objects of the present study is to verify the result of field survey.Other purpose is to clarify the inflow fluxes of N and P into Osaka Bay by field survey and to examine the flow structure in detail by a three-dimensional baroclinic flow model.
(1) Field survey to clarify fluxes of N and P
Simultaneous measurements in Osaka Bay were conducted on 23rd August in 1997.12 hours measurements of velocity, temperature and salinity, and water sampling were done in the sections across Osaka Bay along about 20 m depth and Tomogashima Channel.And, during the same time, STD and water sampling were done in Akashi Straits.As a result, in regard to the balance of N, 24 ton during one day inflows through Akashi Straits and 35 ton outflows thorough Tomogashima Channel.In the case of P.68 ton inflows and 1 ton outflows That means that 11 ton of N outflows from Osaka Bay and 67 ton of P inflows.On the other hand, 16 ton of N and 5 ton of P are transported toward the head of bay by estuarine circulation.
(2) Numerical experiment
At first, the flow and density structures are computed in the large scale domain including Osaka Bay, Harimanada Sea and Ki-i Channel with 1,000 m horizontal resolution and 10 layers in vertical direction in order to obtain the boundary conditions for the small scale domain of computation near the Kitan Straits.Secondly, the small scale computation with 250 m clarifies the production mechanism of large scale eddy near the straits, residual current system, water exchange and so on.
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Research Products
(8 results)
