2010 Fiscal Year Final Research Report
THERMAL CONVECTION PHENOMENA DURING COOLING PERIOD IN THE NORTHERN PART OF LAKE BIWA AND EMERGENCY COUNTERMEASURES OF DO DEPLETION NEAR THE BOTTOM OF LAKE
| Project/Area Number |
20560477
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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 |
Hydraulic engineering
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| Research Institution | Kyoto University |
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Principal Investigator |
HOSODA Takashi Kyoto University, 大学院・工学研究科, 教授 (10165558)
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| Co-Investigator(Kenkyū-buntansha) |
TAMURA Mssayuki 京都大学, 大学院・工学研究科, 教授 (90109900)
ONDA Shinichirou 京都大学, 大学院・工学研究科, 助教 (50402970)
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| Project Period (FY) |
2008 – 2010
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| Keywords | 琵琶湖 / 地球温暖化 / 水質 / 熱対流 / 貧酸素化 / 土木環境工学 |
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| Research Abstract |
It is an increasing concern that the depletion of dissolved oxygen (DO) concentration at the bottom layer of the northern-part of Lake Biwa with 100m in maximum depth has been worsen in recent years not only due to eutrophication in water but also the effects of global warming such as the raise of air temperature during winter. Since it is known that the thermal convection during the cooling period is the main mechanism of the vertical DO transfer from the surface to the lake bottom, the fundamental features of mixing processes caused by thermal convection were clarified using the results of 3D CFD simulation. Then, the electrolysis of water at the lake bottom for the restoration and DO recovery is considered as one of the countermeasures proposed by Lake Biwa Environmental Research Institute, Shiga Prefecture. The simulation model was developed to predict the effectiveness of the electrolysis in the lake. A mechanical setup to enhance the vertical mixing was also proposed as the other countermeasure technique.
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