According to Coutex, sluice gates are movable gates set over a moving body of water that control the quantity of water permitted to flow through the gate. Raising the gate increases water flow, and lowering the gate reduces it. Some sluice gates are fully automatic and equipped with water pressure sensors that determine the gates' ideal position, while others are operated by hand.
Common locations for sluice gates are rivers, canals and creeks. Sewage treatment plants, mines, mills and refineries also employ this technology.
There are several styles of sluice gates. Flap gates are vertical, automated and rely on pressure sensors to open and close. Gates of this type without pressure sensors are called vertical rising sluice gates.
Radial sluice gates consist of cylindrical sections placed horizontally across the water. Each gate has a series of embedded rods which the gate operator controls to manipulate the cylinder and adjust the water flow.
The fourth type of sluice gate is the needle gate, which operates on the same hydrodynamic principle as a needle dam. Each needle gate features an array of large, thick, freestanding needles braced vertically against a horizontal scaffold. The pressure of the water flowing through the gate holds the needles in place.
Miniature sluice gates called sluice boxes are staples of small mining operations. They act as filters that collect tiny stones and pieces of valuable ore.