Kazuo OKAYAMA 1 , Yasuji TAKANO 2
1 Director, River Environment Division, River Bureau, Ministry of Land, Infrastructure and Transport(MLIT), 2-1-3 Kasumigaseki, Chiyoda-ku, Tokyo, 100-8918, Japan
2 Technical Councilor, Japan Water Resources Environment Technology Center (WEC), 2-14-2 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan
The number of dams in Japan increased year by year. The dams in the management phase placed under the direct jurisdiction of the Ministry of Construction (MOC) numbered 471 in 2003, an increase by 119 in the decade since 1993. The total reservoir area is approximately 90,000 km2, occupying about 20% of Japan. The reservoir area is certainly expected to increase further with the future progress of dam projects.
Dam construction requires a wide project area in a limited mountainous region, so it has a great impact on the area around the dam site and may involve the following problems: (i) Community as a basis of life in the area surrounding the submerged area is often lost. (ii) There may be public concern about the reconstruction of lives because of difficulty in finding land for resettlement and in securing employment opportunities in the limited mountainous area. (iii) The benefits of the dam for controlling floods and using water are enjoyed only by the downstream residents, so reservoir area residents firmly complain about the unfair advantage taken by the people in downstream areas.
The problems have been becoming outstanding with the recent decrease of appropriate dam sites and social and economic changes, and making a big roadblock to the promotion of dam construction.
Then, there emerge the needs during dam construction for reconstructing the lives of residents in the area to be submerged, developing the basis for life in the reservoir area and encouraging closer mutual relationships between the people in the downstream and upstream areas. Measures to meet such needs are collectively referred to as reservoir area development.