| Co-Investigator(Kenkyū-buntansha) |
KURAJI Koichiro Tokyo Institute of Technology, Lecturer, 大学院・総合理工学研究科, 講師 (90282566)
FUJIWARA Hirokazu Hachinohe National College of Technology, Associate Professor, 建設環境工学科, 助教授 (70199389)
NISHIDA Shuzo Osaka University, Associate Professor, 工学部, 助教授 (40172663)
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| Research Abstract |
The currents and salinity circulation mechanism of Lake Ogawara, a large brackish water lake in Aomori prefecture, is investigated by field experiments and numerical simulations as well as their effects on the biology of Corbicula Japonica that is a species of Clams and the major and important product of fishery in the lake.
In 1997, the dynamics of salinity under flow, which is a characteristic of the salinity circulation of this lake, was clarified by field measurements. A new techniques for measurements of growth rate of Corbicula Japonica was also developed as the first step of the study on its biology. In 1998, the seawater intrusion and mixing process in Takase River, the outflow from the lake, was studied by field experiments. In the lake, the spatial distribution of infant clams of Corbicula Japonica was surveyed. The algae distribution and the transportation routes of nutrients for its propagation were also investigated by field measurements and numerical simulations because algae is a major food for Corbicula Japonica. In 1999, hydraulic data concerned with the salinity circulation, which have been collected by lake management office, were restored for missed parts and modified for inaccurate parts, and then a probabilistic model of seawater intrusion was constructed by using the data so as to estimate the stochastic feature of the seawater intrusion and the salinity condition of the lake. Internal oscillations and vertical mixings in the lake caused by strong winds and density effects were also clarified by detailed field measurements. As for Corbicula Japonica, the development of their spawning condition at shallow area near the lake exit was investigated from the standpoint of hydraulics by field measurements and numerical simulations. With the results obtained in 1998, a view about biology of Corbicula Japonica in the lake was obtained from the hydraulic standpoint.
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