Numerical Modelling of Water Quality Environment in Coastal and Estuarine Waters

本研究的目的是发展通用的，可靠的数值模式预测水质在沿海和河口沃茨，严重依赖于斜压效应，由于盐度和/或水温的差异。这种沃茨中的流动特征可分为三种：一维充分混合流、垂向二维分层流、三维分层流（其中包括水平二维充分混合流）。将变密度场中的时变空间分布流与水质动力学耦合，建立了各类别的模型。本文的主要研究成果如下：1.采用有限元方法，建立了适用于变密度流场的通用性强的流动模型，并对模型的稳定性、精度（主要通过台架试验）和求解效率等数值特性进行了研究 关于我们 一维和三维问题，建立了基于描述水质物质变化的对流-弥散方程的有限元水质模型。通过将水质模型与水流模型耦合，建立了比传统箱形模型更为精细的水质预测模型。3.对于垂向二维问题，水流模型可以用于研究浮游生物的垂直运动、停滞和浓度，从而有助于了解赤潮发生的机理。建立了生物系统的初步模拟模型，并对其基本数值特性进行了检验。此外，本文还提出了一个河流水质控制模型，并验证了该模型的有效性，作为后续研究，有必要进一步考察所建模型的解的重现性，并讨论未知参数的估计和识别方法。少

The purpose of this study is to develop versatile, reliable numerical models for perdicting water quality in coastal and estuarine waters that depends heavily on baroclinic effects due to difference in salinity and/or water temperature. The flow in such waters is charactreristically categorized into three ; one-dimensional well-mixed flow, vertically two-dimensional stratified flow, three-dimensional stratified flow (in which horizontally two-dimensional well-mixed flow is included). The model for each category is built by coupling time-dependent spatially distributed flow in variable density field with water quality dynamics. The fruitful results obtained through this study are summarized as follows.1.Flow models of high versatility, applicable to variable density field, were newly developed for the respective categories by employing the finite element method, and their numerical properties (stability, accuracy (mainly by rig-testing) and solution efficiency) were investigated.2.For o … More ne-dimensional and three-dimensional problems, finite element water quality models were developed based on the convection-dispersion equation that describes variation of the water quality substances. By coupling the water quality model with the flow model, water quality prediction models, far refined than the conventional box models, were built.3.For vertically two-dimensional problem, it was shown that the flow model was capable of being used for investigating vertical movement, stagnation and concentration of plankton, and therefore useful for understanding the mechanics of red-tide generation.4.For future perspective of the study, a primary simulation model for biological system was developed and its basic numerical properties were tested. In addition, a water quality control model for rivers was proposed and its validity was demonstrated.As the follow-up study, it is necessary to further investigate solution reproducibility of the models developed, and to discuss the methodology for estimation and identification of the unknown parameters involved. Less