IWRA Proceedings

Because of the increasing needs in recent years for an environment with a higher living standard and abundant water, it is becoming important to recognize the functions of rivers, such as provision of a variety of natural environment and waterfront spaces to local communities, and there has been a growing demand for preserving and sharing river environment. The importance of rivers is now widely recognized, since they not only serve as flood and high-tide prevention facility (flood control) and water resource (water use) but also help preserve rich natural environment and create a high-quality living environment in local communities. Since ancient times, rivers have been playing crucial roles in creating the features and culture of local communities, and serving as common property. In recent years, there has been a growing trend to rebuild the relationship between human and rivers that had been weakened due to the rapid urbanization and intensive land use, and it is becoming important that river management takes into consideration the characteristics of rivers and the features and culture of local communities, and enhances the virtues of the communities. This indicates that rivers must be improved by both the local residents and the municipal government, not by the river administrator alone, and that they need to build a partnership to preserve rivers as the common property. In response to this background, the River Law was revised in 1997 to add "Improvement of River Environment" to its original two purposes, i.e.,"Flood Control" and "Water Use," and procedures to reflect opinions of local residents in river improvement at the planning stages were established. This report represents the background of the revision of the River Law, concept of river improvement based on the revised River Law, and the example of the improvement plan for the Tama River. 2. Revision of the River Law 2.1. Preceding River Law and river improvement planing system Since the first River Law was formulated in 1896, the modern river improvement system in Japan has a history of about 100 years. The law was revised several times in accordance with the changes in economic and social status. The revision in 1964 aimed to establish a comprehensive system for flood control and water utilization, including the introduction of basinwide management system. In parallel with the revision of the River Law in 1964, it was decided that the Basic Plan for the Implementation of Construction Works be prepared by each river administrator under the framework of the river improvement planning system, so that river systems would be improved in a consistent manner. However, although river administrators consulted with the River Council when preparing the Basic Plan, the final decision was usually made by themselves. In addition, the contents of such a basic plan were not detailed enough and were insufficient as a means for river improvement. 2.2 Revision of the River Law Due to the socio-economic changes afterwards, the river environment has dramatically changed in recent years. Nowadays, rivers serve not only for flood control and water use but also as an environment that provides various species of wildlife with abundant water and habitats. In parallel with this, demands for creating rivers which form the culture of regional communities in accordance Director, River Planning Division, River Bureau, Ministry of Land, Infrastructure and Transport (MLIT), 2-1-3Kasumigaseki, Chiyoda-ku, Tokyo, 100-8918, Japan Executive Director, Infrastructure Development Institute (IDI), 5-3-23, Kojimachi Chiy oda-ku, Tokyo, 102-083, Japan with their characteristics are growing. Figure. 1 Past Amendments on the River Law In response to this background, the River Law was revised in 1997 to incorporate the following contents with respect to the relationship between river environment and residents in local communities (Figure.1). 1) Improvement and preservation of river environment With the main purposes being flood prevention and water use, the River Law before revision aimed to utilize rivers for such purposes as preventing disasters due to floods and high tides. The 1997 revision added "improvement and preservation of river environment" to the preceding two purposes "flood control" and "water use." This indicates that the revised law is not only for the natural environment of rivers, but also for the living environment for human beings supported by rivers, and that it is essential to take into consideration the balance among "flood control", "water use" and "improvement and preservation of river environment" for comprehensive river control. 2) Review of river improvement planing system It was decided to divide the former "Master Plan for River Works" into "Basic River Development Policy" which lays down long-term policies for river improvement, and "River Development Plan" which lays down 20- to 30-year policies with details of necessary activities. The latter has more detailed policies for creating proper river environment than the "Master Plan for River Works," and incorporates procedures to reflect opinions from local community residents and the heads of municipalities (Figure.2). 2.3 Creation of river environment reflecting local communities' opinions "Basic River Development Policy" lays down long-term policies, which allow river administrators to carry out river improvement (construction and maintenance of river structures) while taking into consideration the balance among river systems nationwide, and which serve as guidelines for the determination of key factors such as design flood; allocation of water volume to river channel and flood control facilities; and design flood discharge...