A set of high-definition waterfall and stream picture desktop wallpapers are shared with everyone. Wallpaper size: 3840x2160. A waterfall is water flowing down from a mountain wall or a place where the river bed suddenly drops. From a distance, it looks like a hanging white cloth.In geology, it is called falling water, which is the phenomenon of river water falling vertically from high altitude when flowing through faults, depressions and other areas.