Irrigation Water Operation and Water Quality Management in Large Scale Water System

土地和水是水稻农业不可或缺的资源，本研究的目的是阐明灌溉水系统运行的绩效，并评价灌溉水系统运行对流域水质管理的贡献。(1)通过对几个流域灌溉用水现状的调查，运用多元分析方法，研究了灌溉用水与各相关因素之间的关系。(2)近年来，由于农村社会的城市化和现代化，农民在水协会中的利益发生了显著变化。通过调查和分析，阐明了这一变化的原因。(3)本文试图探讨塔河流域传统溪流的各种功能。根据控水原理，从环境保护的角度评价了河沟的作用。(4)采用复水箱模型分析了河沟水系统的水量平衡及各组成部分，并对河沟水系统的水质进行了分析，认为河沟水系统中回流的存在提高了水资源的利用效率，但对河沟水系统的水质有严重影响。(5)河沟地区实行稻田与其他作物轮作，通过净出水水质分析评价该地区的水质状况。

Land and water are essential resources for paddy agriculture.The purposes of the study are to clarify the performances of irrigation water system operation and to evaluate the contributions of the water system operation to water quality management in river basins.(1) The practices of irrigation water use were surveyed and the relationships among the water use and several concerning factors were considered by multivariate analysis in several river basin areas.(2) There arc, recently, remarkable changing of farmers' interests in their water associations, because of urbanization and modernization in rural communities. Surveys and analyses were conducted for clarifying the change in aspects and reasons concerning on it.(3) It was tried to investigate various functions of traditional creeks in tower river basin. Based on principles of water control, the roles of creeks were evaluated from environmental conservation side.(4) The water balance and concerning components were analyzed using a complex tank model for creek water system, The water quality was also examined.The existence of return flow in the creek water system improve the efficiency of water use, but may have severe impacts on water quality in creek networks.(5) There are rotational land use of paddy and other crops in creek area.The net effluent toad analsis was conducted for evaluating the status of water quality in the area.