Rocky thresholds in the mountain river. Foamy stream of fast flowing water. Small rivers can be referred to using names such as stream, creek, brook, rivulet, and rill. Stone stones forest mountain green fresh hydrological cycle. A stream is a body of water with surface water flowing within the bed and banks of a channel. Moss mossy alga lichen stream watercourse creek brook valley gully rivulet runlet water. Fast flowing raging river. Giant roiling water. The stream encompasses surface fluxes that respond to geological, geomorphological, hydrological and biotic controls. 4K 3840×2160.