Gates are control devices used for closing and opening water discharge channels. An essential component of hydraulic structures, they can intercept water flow, regulate water levels, modulate flow rates, and discharge silt and debris, among other functions.

The gate is mainly composed of three parts:
① The main activity section, used to close or open apertures, commonly referred to as a gate, also known as a leaf gate.
② Embedded section
③ Closure Equipment.
The activity section includes weighing structures such as panel beams, support and walking parts, guiding and sealing devices, and lifting lugs. The embedded section includes main tracks, guide tracks, hinge seats, lintels, thresholds, and sealing seats, which are embedded around the orifices and securely connected to the concrete of hydraulic structures with anchor rods. They form supports and sealing surfaces on the door leaves to transfer the water pressure and other loads on the door leaf structure to the hydraulic structures and achieve good gate sealing performance. The operating machinery is connected to the lifting lugs of the door leaf to control the position of the activity section, but some gates also rely on hydraulic automatic control for operation.