Social Discovery on Irrigation, Drainage and Reclamation System in the Context of Upgrading Facilities and Diversified Purpose ; Special Reference to the Decision-making in Rural Communities

本研究的目的是提出农村社区发展水稻种植的灌溉、排水和稻田的设计和建设方法，明确农村社区为决策的基本单位。本研究的特点是将社会工程学的方法与农业经济学和农业土木工程学相结合。研究结论如下：1）在关注群体成员之间权力关系的基础上发展了群体决策理论。特别指出了土地改良区对农村社区决策支持的有效性。2）通过建设大面积稻田来减少供水设施，以建立可持续的稻田农业。但是，这种方法并不一定会导致航道密度的降低。为此，应在设计阶段通过社区成员之间的充分讨论，引入土地整理的方法，即在佃农和所有者之间交换农地使用权。3）利用GIS有效地利用水和农田，而土地改良区最适合作为该系统的操作者或管理者。考虑到供水设施的农业用途的溢出效应，市政当局和受益地区的非农民的货币和劳动力支持对于维护这些设施是必不可少的。

The purpose of this study is to propose the method of designing and constructing irrigation, drainage and paddy plots where a rural community is developing its paddy farming, specifying the rural community for a fundamental unit of the decision-making. The characteristic of this study is to apply the social engineering approach to this question in collaboration with agricultural economics and agricultural civil engineering. Our conclusions are as follows.1) We developed the group decision-making theory while paying attention to the power relations between community members. Especially we pointed out the effectiveness of the support of the Land Improvement Districts in the decision-making of rural community.2) It is necessary to reduce the water supply facilities by the construction of large-sized paddy plots to establish the sustainable paddy farming. However, this method does not necessarily lead to the decrease in the density of the waterway. For this decrease, the method of land consolidation by exchanging user right of farm plots between tenant farmers and owner farmers should be introduced through a thorough discussion among community members at the design stage.3) It is effective to use GIS for efficient use of water and the farmland, and the Land Improvement Districts is the most suitable as the operator or the manager of this system.4) Considering the spillover effect of the agricultural use of the water supply facilities, monetary and labor support of the municipality and non-farmers in its beneficiary area are indispensable for the maintenance of these facilities.