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:
①The main operational section, used to close or open apertures, commonly referred to as a gate or a gate leaf.
② Settled section
③ Valve equipment.
The activity section includes weight-bearing structures such as panel girders, support rolling parts, guiding and waterstop devices, and lifting lug, etc. The embedded part includes main rail, guide rail, hinge seat, lintel, sill, waterstop seat, etc., which are embedded around the opening, securely connected to the concrete of hydraulic structures with anchor bars, forming supports for rolling parts and waterstops on the door leaf to transfer the water pressure and other loads on the door leaf structure to the hydraulic structure, and achieving good gate waterstop performance. The operating mechanism is connected to the lifting lug of the door leaf to control the position of the activity section, although a few gates operate automatically with hydraulic control.