Abstract
Many irrigation ponds existed in Nagoya City especially in the eastern hill area before. There are still 113 irrigation ponds though the number of ponds decreased sharply with the progress of land development since the former half of 1960's. The city formed Nagoya City Conference for Environmental Preservation of Irrigation Ponds in 1973, surveyed all the ponds in the city, and settled on Basic Plan for Environmental Works of 96 ponds that their evaluation on flood control or environmental side was high. At the same time, alteration, abolition and repairing of the ponds became the considerations that needed decision by the conference. In 1992, the city legislated Irrigation Ponds Conservation Ordinance. Thus, Nagoya City has been engaged in conservation of irriagation ponds with all its might. In Nagoya City, there are many public-owned ponds and this promotes their conservation. As for making the ponds public-owned, the relation to land readjustment is deep, and the most of land development in Nagoya City have depended on the land readjustment. Concretely, the irrigation pond is made public-owned after bottom ground of the pond is exchanged for housing lot with the same value as the bottom ground. It seems that 43 ponds at least were made public-owned by land readjustment. Besides, it seems that 20 ponds were made public-owned by purchase or donation. Also, 66 ponds are used as parks and 54 are used as flood regulation ponds. These ponds contribute to an increase of green tract rate and flood control. As mentioned above, the utilization and conservation measures of irrgation ponds by Nagoya City serves as a good reference when the ponds are maintained at the urbanized area.
