Sluice Gate

A sluice is a water channel fitted with a sluice gate, a movable barrier that is raised or lowered to control the flow and level of water passing beneath it, traditionally worked by a hand-turned chain, worm drive, or rack and pinion, and by electric or hydraulic power in modern installations. Sluices direct water to turn mills, float logs down from mountain streams, and regulate levels in canals and drainage channels, and a lowered gate can itself act as a small weir once water begins to spill over its top rather than pass beneath it. The Dutch hydraulic engineer Jan Blanken invented a self-opening variant, the fan gate, in 1808, a design that opens under water pressure alone and was historically used to flood land for defense.