Estimation of Dynamic Characteristics of Water Environmental Elements in a Brackish and Fresh Water Lake and Development of an Ecosystem Model in Closed Water Area

通过野外观测、水力模型试验和数值模拟，对封闭水域水质项目的行为进行了估算、表征和预测。其后果总结如下。(1)微咸湖泊水质变率研究2003 ~ 2005年对小山湖进行了水质和微气象项目的连续测量。我们通过小波分析检验了DO的可变性。同时，利用混沌工程领域发展起来的局部逼近方法对DO的短时时间跃迁进行了预测。2)半封闭海湾环境行为的数值模拟。建立了考虑生态系统过程的多哥平原区低洼水田灌溉期水体水质（氮、磷）日变化的数学模型。同时，通过数值模拟评价了含tbt防污涂料在有明海北部的环境行为和命运。在此基础上，建立了日本有明海的二维深度平均有限差分数值模型，用于预测潮流和SS。3)封闭水域密度流的水力学模型试验研究了封闭水体中基于风致流力学扰动的漂浮植被表面覆盖度对湍流结构的影响。因此，漂浮植被的存在对湍流夹带的规模有显著影响。当水面部分被漂浮植被覆盖时，水面和密度界面附近水平方向湍流能量随着漂浮植被覆盖面积的增加而减小。少

The field observation, hydraulic model experiment and numerical modeling were carried out for an estimation, characterization and prediction of the behavior of water quality items in enclosed water area. The consequences were summarized as follows.1)Variability of water quality in a brackish lakeA continual measurement of water quality and micrometeorological items was carried out in Lake Koyama from 2003 to 2005. We examined the variability of DO by the wavelet analysis. Also, the prediction in short-term the time transition of DO was done using a Local Approximation method developed in the chaos engineering field. In addition, a 3-dimensional analytical model was constructed by utilizing the operator splitting method to examine lake currents and salinity dispersion, and was applied to Lake Togo.2)Numerical modeling of environmental behavior in a semi-closed bayA mathematical model was developed for predicting the daily variation of creek water quality (nitrogen and phosphorus) in the … More flat low-lying paddy-cultivated area during irrigation period by considering ecosystem processes. Also, the environmental behavior and fate of TBT-containing antifouling paints in the northern Ariake Sea were assessed by numerical simulations. Furthermore, the 2-dimensional depth-averaged finite difference numerical models have been developed for predicting the tidal flow and SS in the Ariake Sea, Japan.3)Hydraulic model experiment for density current in closed water areaWe experimentally investigated the effect of the surface coverage of floating vegetation on the turbulent structure based on the mechanical disturbance of wind-induced flow in a closed water body. As a result, the presence of floating vegetation had a significant effect on the scale of the turbulent entrainment. When the water surface was partially covered with floating vegetation, the turbulent energy in horizontal direction was decreased at water surface and neighborhood of density interface as the surface coverage of floating vegetation increased. Less