Dig Canal
Dig Canal is a command players can give to citizens. This allows the player to select an area via clicking and dragging to be dug out. This can only be done on open, outside ground. Once a canal is dug, it will immediately be filled with water, which can be removed via another command.
Like standard ground, canals can be walked over, even if they're filled with water. Unlike natural water that's placed by the game, water-filled canals do not increase fertility, but they can provide farms some irrigation if the water tiles are right next to the farm, making farms work much better.
Water can be removed from canals with the Remove Water command.