Gates are control devices used to close and open water discharge channels. An essential component of hydraulic structures, they can be used to block water flow, control water levels, regulate flow rates, and discharge silt and floating debris, etc.

The gate is mainly composed of three parts:
① The main activity section, used to close or open apertures, commonly known as a gate, also referred to as a gate leaf.
② Grouted section
③ Valves and Shut-off Equipment.
The activity section includes weight-bearing structures such as panel girders, support and travel components, guidance and sealing devices, and lifting lugs. The embedded part includes main tracks, guide tracks, hinge seats, lintels, sill plates, and sealing seats, which are embedded around the openings and securely connected to the concrete of the hydraulic structure with anchor rods, forming supports and sealing surfaces for the door leaves to transfer water pressure and other loads from the door leaf structure to the hydraulic structure, and to achieve good gate sealing performance. The opening and closing mechanism 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.