| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥700,000 (Direct Cost: ¥700,000)
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| Research Abstract |
Two kinds of numerical models were developed for analyzing flow movement in a shallow lake. They are both two dimensional unsteady flow simulation models based on the finite element method, but one is horizontal and the other is vertical.
The former model can simulate horizontal water movement and can be used for the analyzes of pollutants' inflow, outflow, diffusion and dilution, if velocities are vertically equally distributed. This model was used for analyzing flow patterns in the Kasumigaura lake and in the lnbanuma lake. It was found that wind effects were primary in the Kasumigaura lake, and pumping operations were strongly effective in the lnbanuma lake. Three dimensional model, which was in the original plan, is not completed, although now approaching final stages through improving its numerical stability.
The later model can calculate vertical water movement and is suitable for tracing floating materials, such as microcystis. This model was used to investigate bahaviors of floating materials when dilution water was released in a harbor. Released water may be hot or cold.
On the other hand, the long-term muddy water problem in a dam reservoir was studied at field, and in vertical one dimensional simulation model as well. The field study was aimed at gathering hydrological and water-quality data before and after large flood. These data were used to investigate muddy water generating process. One dimensional model was used for examining the effectiveness of curtain wall and bypass channel, which might be used to prohibit inflow water from being mixed with muddy water in a reservoir.
Through the above studies, simulation models for solving water envitonmental problems are nearly completed but should be improved to gain a better prospect.
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