For the scheme of tailrace tunnel with variable crown heights, tailrace surge chamber can be omitted,but pressure and interface between free flow and pressure flow would vary with flow transition.

• 向家坝水电站尾水下接金沙江,江水位变幅大,尾水隧洞选用变顶高尾水洞方案时可不建尾水调压室,但洞内压力和明满交界面会随水流过渡过程变化。