Which process describes the changing of a river or stream's course?

The process that describes the changing of a river or stream's course is avulsion. Avulsion occurs when there is a sudden change in the flow of a river that results in the river cutting a new path and abandoning its previous channel. This can happen due to natural events, such as flooding or landslides, which force the river to switch courses rapidly.

Avulsion is significant because it can have legal implications concerning property boundaries, especially when land changes hands as a result of the river altering its course. In contrast to gradual processes like erosion or sediment deposition associated with accretion, avulsion is marked by its immediacy and can create new landforms and alter existing ones in a short time frame.

Understanding this distinction is essential for surveying and understanding land use in areas near waterways, where property boundaries may be influenced by the natural shifting of streams and rivers.