Students are introduced to the structure, function and purpose of locks and dams, which involves an introduction to Pascal's law, water pressure and gravity.. Download scientific diagram | Illustration of downstream boat passage in a typical lock and dam. Note that both the downstream emptying valve and downstream miter are closed as a lock cycle begins.
How a Dam and Lock System Works To move a ship or boat going downstream to a lower water level, the lock is filled by opening the filling valve. Then the drain valve and upstream and downstream gates are closed so the chamber water level rises to the upstream level. Then upstream gate opens and the boat moves in.. Three Gorges Dam lock near Yichang on Yangtze river, China. A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a chamber in a permanently fixed position in which the water level can be varied.