Study on development and improvement of simulation model for environmental prospect of lake water system

建立了两种分析浅湖水流运动的数值模型。它们都是基于有限元法的二维非定常流场模拟模型，但一个是水平的，一个是垂直的。前一种模型可以模拟水的水平运动，在流速垂直均匀分布的情况下，可用于分析污染物的流入、流出、扩散和稀释。利用该模型对霞aura湖和inbanuma湖的水流形态进行了分析。结果表明，风对霞aura湖的影响是主要的，而在inbanuma湖，抽水作业是非常有效的。原计划中的三维模型尚未完成，但通过提高其数值稳定性已接近最后阶段。后一种模型可以计算水的垂直运动，适合于追踪漂浮物质，如微囊藻。利用该模型研究了港口释放稀释水时漂浮物的行为。释放的水可能是热的，也可能是冷的。另一方面，对某大坝水库长期泥水问题进行了现场研究，并建立了垂直一维模拟模型。野外研究的目的是收集大洪水前后的水文和水质资料。利用这些数据对泥水生成过程进行了研究。采用一维模型考察了幕墙和旁通通道的有效性，可用于防止入流水与水库泥水混合。通过以上研究，解决水环境问题的模拟模型已经基本完成，但还需要进一步完善，以获得更好的前景。

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.