Abstract
The development of new dam sites is decreasing recently by geological and environmental problems.
On the contrary, redevelopment of existing dams by raising their height will increse in the future, since this method has outstanding merits; for example, high ratio of storage volume/raised-height (high economical feasibility), and easiness of purchase of new land area (small impact on environment).
Design and construction of rasing dam height should take into account of functions of exising dams; flood control, irrigation, and water supply, etc.
Kayaze dam, of concrete gravity type, 51.0m high, built in 1962 by Nagasaki prefecture, is now under construction by raising its height by 14.5m.
