The sluice for flood discharge and drainage is also called drainage sluice. It is usually located at the outlet of river drainage in flood-stricken areas. The drainage gate on the irrigation channel is used to discharge the excess water in the irrigation channel, such as the flood in the catchment area of the canal system in flood period, which is generally called the drainage gate. Located at the end of the channel, it is used to drain the accumulated water in the channel and facilitate the maintenance of the channel, which is called a sluice. Located at the end of the channel, it is used to drain the accumulated water in the channel and facilitate the maintenance of the channel, which is called a sluice. Drainage sluice built at the outlet of coastal drainage channel, also known as tidal sluice.