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

建立了两种浅水湖泊水流运动的数值模型。这两个模型都是基于有限元方法的二维非恒定流模拟模型，一个是水平的，一个是垂直的，前者可以模拟水平的水流运动，在流速垂直均匀分布的情况下，可以用来分析污染物的流入、流出、扩散和稀释。该模型被用来分析柏浦湖和印巴努马湖的水流形态。研究发现，风的影响在鹿儿湖是主要的，而抽水作业在印巴努马湖是非常有效的。原计划中的三维模型虽然通过提高数值稳定性已接近最后阶段，但尚未完成，后者可以计算水体的垂直运动，适用于微囊藻等漂浮物的示踪。该模型被用来研究港口释放稀释水时漂浮物的行为。释放的水可以是热的，也可以是冷的。另一方面，在现场和垂直一维模拟模型中，研究了大坝水库的长期浑水问题。实地研究的目的是收集大洪水前后的水文和水质数据。这些数据被用来研究浑水的产生过程。用一维模型检验了幕墙和旁路渠道对防止水库进水掺入浑水的效果，通过以上研究，解决水环境问题的模拟模型已接近完成，但仍需改进，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.