lock emptying system
/ˈlɒk ˈɛmptiɪŋ ˈsɪstəm/
n
English · lock emptying system中文 · 船闸泄水系统Español · sistema de esclusas de vaciado y desagüeFrançais · aqueduc de vidange
意味：Conduit that evacuates the water from the downstream side causing the water level in the lock-chamber to go down.