| Project/Area Number |
05402057
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAKAMURA Riota The University of Tokyo, Faculty of Agriculture, Professor, 農学部, 教授 (10011991)
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| Co-Investigator(Kenkyū-buntansha) |
KUBO Naritaka The University of Tokyo, Faculty of Agriculture, Instructor, 農学部, 助手 (40134506)
SHIMADA Masashi The University of Tokyo, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (10272436)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥19,900,000 (Direct Cost: ¥19,900,000)
Fiscal Year 1995: ¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1994: ¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 1993: ¥8,900,000 (Direct Cost: ¥8,900,000)
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| Keywords | closed water body / long-term turbidity water / lake and reservoir eutrophication / tank model for water quality simulation / vertical one-dimensional model |
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| Research Abstract |
During our research we fortunately experienced a big flood that was estimated to be once for two hundred years. This flood brought us many important data and much information. As a first step, we analyzed this flood's hydrological characteristics. The rainfall that caused the flood was turned out through this analysis that daily intensity was not so heavy but hourly intensity was very strong. We next examined the influence of this heavy rain against catchment area, and especially compared changes of both runoff patterns and stream water qualities before and after the flood. As a result, We knew that a small scale floods after the big one could make stream water 10 times more turbid than those before that. We also compared the clarified processes of two reservoirs after the flood. These two are locating both east and west sides of a mountain and storage capacities are almost comparable. There was a big difference between two reservoirs' purification processes, which was concluded to be caused by the difference of dam operations. One reservoir is operated only for agricultural water usage, but the other has two objectives, agricultural water use and hydroelectric water use. This fact suggested that water turbidity might be lowered throught dam operations and water managements. We tried hydraulic model experiments. First experiments were aimed for examining performance of a selective withdrawal, but it was not so effectual. We next designed a curtain wall, which will be installed along the water course within a reservoir and prohibits turbid water's diffusion, and examined its effectiveness. When the wall was installed downstream of a plunge point with tight, it was very effective. Through above observation we could gain many data, which advances our study. But for the practical use of the curtain wall we need further observation and data.
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