ABSTRACT
The dam of Dachaoshan hydropower station is a RCC gravity one with five crest overflowing orifices, which have a unit discharge of 222 m3/s.m at the check flood level. By entire and local model tests, crest overflowing orifices adopted the technology of combined energy dissipator of flaring gate pier, stepped overflow surface and flip bucket. In June, 2002, the prototype observation was carried out to verify the design and operating conditions when the reservoir reached the normal water level (design flood level). The test results illustrated the characteristics of flow at high water head and large unit discharge. In February 2003, the comprehensive inspections to the structure was done, which reflected that the combined energy dissipator was in good condition after a flood season.
