Avulsion (river)

In sedimentary geology and fluvial geomorphology, avulsion is the process by which flow is diverted out of an established river channel and into a new course via a bifurcation, or splitting of the channel. Avulsions range from full, in which all flow is diverted from a one channel to another, to partial, in which only a portion of flow is diverted. Avulsions were once thought to occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course (i.e., the slope advantage of one channel over another), but it is now recognized that many factors, including upstream channel planform, channel cross-sectional geometry at a bifurcation, and channel obstructions such as wood or beaver dams can also influence the rate and progression of avulsions.