水布垭枢纽放空洞主要承担水布垭工程施工期后期导流及完建后大坝检修时放空水库的任务。它具有水头高、水位变幅大、流速大、运行时间长等特点，经过1∶58水工整体模型多种方案的比较研究，首次提出了一种新型的双曲双槽差动鼻坎消能工形式；经过2007年超高水位、长时间的泄洪运行检验，该消能工成功地解决了放空洞高水头、大变幅、大夹角、窄河谷且地质条件较差的消能防冲难题；同时，该型鼻坎消能工无任何蚀损。

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.