ABSTRACT
This is the first case applying a stepped spillway to a concrete gravity type dam in Japan. This dam has the wide uncontrolled overflow crest and side stepped channels on the dam foot (dam-foot training channel) to conduct flow to the narrow stilling basin, because the catchment area is small and the dam design flood discharge is much larger than the maximum inflow during the flood control operation. In order to reduce the training wall height of the dam-foot training channel, the stepped spillway was applied. And emphasizing horizontal stripes of steps, the downstream view of the dam has become beautiful. Hydraulic model studies were carried out at PWRI laboratory from 1989 to 1990.
