Water environment of irrigation and drainage systems and optimal water control in flat low-lying areas along a coastal zone

在沿海地区的平坦低洼地区，灌溉和排水系统的最佳控制取决于对水流状况的准确理解。在高水位季节，需要对洪水径流现象进行定量了解，特别是对排水系统进行最佳控制。另一方面，在枯水期，由于死水和海洋现象的影响，必须考虑水质的物理动态，以保持良好的水质。本文研究了沿海平坦低洼地区的水流特征和水质物理动力学，并建立了预测最佳水环境和控制灌排系统的数值模型。首先，应用人工智能模型预测潮汐河的水位。结果表明，人工智能是一种有效的边界条件短期预测技术，可用于优化控制灌溉和排水系统。其次，采用水槽试验和野外观测研究了水体中溶解物质的运移。通过实验研究了明渠流中悬浮物的运移规律，得出了在水面的加热和冷却作用下，悬浮物在垂直和水平方向上的运移以对流为主的结论。悬浮物的输运可以用剪切流的动力结构来解释。最后，在上述研究结果的基础上，运用模糊控制理论，成功构建了水土保持灌排系统最优控制专家系统。

In flat low-lying areas along a coastal zone, the optimal control of irrigation and drainage systems for water-environmental conservation depends on the accurate understanding of flow regimes. During the high water season, a quantitative understanding of flood runoff phenomena is required in particular for optimal control of drainage systems. On the other hand, during the low water season, the physical dynamics of water quality must be considered to maintain good water quality because of the influence of stagnant water and oceanographic phenomena.In this study, we examined the characteristics of flow regime and the physical dynamics of water quality in flat low-lying areas along a coastal zone, and numerical models were obtained to predict optimal water environment and control irrigation and drainage systems.First, Artificial Intelligence models were applied to predict water-stages in a tidal river. It was suggested that Al was an effective technique for the short-term prediction of the boundary conditions that should be used when controlling irrigation aid drainage systems optimallySecond, the transport of dissolved matter in a stagnant body of water was investigated using flume experiments and field observations. It was concluded that the vertical and horizontal transport of dissolved matter was characterized by convection due to the heating and cooling of the water surface aid wind-induced flow The transport of suspended matter in an open channel flow was also investigated with experiments. The transport of suspended matter could be explained in terms of the dynamical structure of shear flow.Finally, based upon the above mentioned results, an expert system for the optimal control of irrigation and drainage systems for water-environmental conservation was successfully constructed using the fuzzy control theory.