(n.) A gate, or valve, by which a flow of water is permitted, prevented, or regulated.

aboideau air lock aqueduct arroyo bed canal creek bed culvert dock gate donga dry bed flood-hatch floodgate flume gate gulch gully gullyhole head gate headrace irrigation ditch lock lock gate nullah penstock race river bed riverway runnel sluice sluice gate spillbox spillway stream bed streamway swash swash channel tailrace tide gate wadi water carrier water channel water furrow water gap watercourse waterway waterworks weir