noun A ravine or gorge, usually one with water running through.
noun An open channel or trough used to direct or divert liquids, especially to carry materials (logs, mined material, etc) or people (as a water slide), especially (but not always) one where the walls are raised above the surrounding terrain rather than recessed like a ditch.
verb To transport (logs of wood) by floating them along a water-filled channel or trough.