Effects of River Flow's Fluctuations on Substance Circulation in Closed Water Body and Basin Management

在我们的研究过程中，我们幸运地经历了一场估计200年一遇的大洪水。这场洪水给我们带来了许多重要的数据和信息。作为第一步，我们分析了这次洪水的水文特征。通过分析发现，造成洪水的降雨，日强度不是很大，但小时强度很大。接下来，我们考察了这次暴雨对集水区的影响，特别是比较了洪水前后径流形态和溪流水质的变化。因此，我们知道，大洪水之后的小范围洪水可能会使溪水比之前的浑浊10倍。并对洪灾后两座水库的清水过程进行了比较。这两座城市位于一座山的东西两侧，存储容量几乎相当。两座水库的净化工艺存在较大差异，这是由于大坝运行方式不同造成的。其中一个水库只用于农业用水，但另一个水库有两个目标，即农业用水和水电用水。这一事实表明，可以通过大坝运行和水管理来降低水的浑浊度。我们尝试了水工模型试验。最初的实验旨在检验选择性撤资的表现，但效果不是很好。接下来，我们设计了一个幕墙，它将安装在水库内的水道上，防止浑水扩散，并检验了它的效果。当墙体安装在下游一个带有紧固点的俯冲点时，效果很好。通过以上观察，我们可以获得许多数据，这对我们的研究有很大的推动作用。但对于幕墙的实际使用，还需要进一步的观测和数据。

During our research we fortunately experienced a big flood that was estimated to be once for two hundred years. This flood brought us many important data and much information. As a first step, we analyzed this flood's hydrological characteristics. The rainfall that caused the flood was turned out through this analysis that daily intensity was not so heavy but hourly intensity was very strong. We next examined the influence of this heavy rain against catchment area, and especially compared changes of both runoff patterns and stream water qualities before and after the flood. As a result, We knew that a small scale floods after the big one could make stream water 10 times more turbid than those before that. We also compared the clarified processes of two reservoirs after the flood. These two are locating both east and west sides of a mountain and storage capacities are almost comparable. There was a big difference between two reservoirs' purification processes, which was concluded to be caused by the difference of dam operations. One reservoir is operated only for agricultural water usage, but the other has two objectives, agricultural water use and hydroelectric water use. This fact suggested that water turbidity might be lowered throught dam operations and water managements. We tried hydraulic model experiments. First experiments were aimed for examining performance of a selective withdrawal, but it was not so effectual. We next designed a curtain wall, which will be installed along the water course within a reservoir and prohibits turbid water's diffusion, and examined its effectiveness. When the wall was installed downstream of a plunge point with tight, it was very effective. Through above observation we could gain many data, which advances our study. But for the practical use of the curtain wall we need further observation and data.