Abstract
In this research, a case study was undertaken in Edogawa-ward in order to identify the change in water management organizations and water activity projects as a result of urbanization in the Tokyo metropolitan area. While some irrigation canals have either been filled in or converted into drainage ditches, other canals have been reevaluated as an important natural resource to be utilized for the improvement of the urban environment. In previous studies on water management, the main focus has been on the irrigation association's ability to cope with urban growth. Although it is recommended that there exists a need for the utilization of irrigation canals after the land improvement districts are dissolved and the canals have lost their primary irrigation function, there has not yet been a full investigation into the actual needs and conditions of such use. For this reason, it is important to consider a new approach to utilize the canals in association with the provision of water resource management in an urban setting.
In this research, functional changes in water supply and the Edogawa-ward community's reactions to those changes are discussed as central issues. First, historical changes in water supply are examined in relation to agricultural activities. Second, the process of change in land improvement districts is examined from the viewpoint of financial characteristics, project changes and water rights. Changes in land improvement districts and the transfer conditions of water rights are also taken into account. Third, the transformation of irrigation canals, which at first were converted to urban sewage drainage after the dissolution of land improvement districts, is examined in "order to identify how the Edogawa-ward municipality re-converted the canals into a water activity facility, in relation to the city planning process.
The urbanization of Edogawa-ward has influenced the irrigation association in this area in many ways. The land improvement districts were reformed after the excavation of Edo River irrigation water, and an agricultural cooperative association took control of the land improvement districts. When the canals lost their irrigation function as a result of the agricultural restructuring, the Edo-ward municipality undertook the responsibility of managing the canals. The canals were once severely polluted due to the construction delay in sewage lines. However, the municipality made an effort to improve the canals to be utilized as water activity facilities, recommended by the municipality's master plan. There have been a great many activities going on in the canals since then, and several groups have been organized to protect the canals' environment. Overall, the improvement of the canals is much appreciated by the community at present, although some issues concerning the existence of different administrative procedures to improve the canals as city parks still remain to be resolved. Moreover, the regulations for the canals' water rights have not yet been established; the water rights related "water activities" are neither defined nor articulated in the present river law. Thus, it is critical to establish laws and regulations on water rights for "water activities" in order to plan and implement the multiple usage of water resources in urban communities. In addition, it is said that water resources in an urban setting, such as canals in Edogawa-ward, are very effective in preventing or mitigating natural disasters. Much attention was paid to the utilization of water resources in the city after the Grate Hanshin-Awaji Earthquake, for example. Therefore, it is very important to make the best use of the irrigation canals which have lost their original function, backed up by appropriate laws and regulations, in order to improve the community's natural and living environment as well as to incorporate prevention measures against natural disasters.
