Abstract: The emptying tunnel of the Shuibuya Project will be used for both the diversion during the late construction and the emptying of the reservoir for maintenance after completion of the dam. It possesses the characters of high head, large variation range of water level , high velocity and long operation time. Through comparative researches of many plans in a scale 1∶58 hydraulic model, a new energy dissipator, i.e. hyperbolic differential dentated bucket lip was proposed for the first time, and the scheme successfully has solved the difficult problems about flood discharging and energy dissipating in the emptying tunnel under the conditions of high head, large variation in water level, big spreading angle, narrow valley and poor rock properties; at the same time, this energy dissipator has no any cavitation erosion phenomenon so far.

Key words: emptying tunnel , flood discharging and energy dissipating, doublecurved differentialdentated bucket lip, energy dissipator