River channel migration is the lateral motion of an alluvial river channel

Channel (geography)

In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...

 across its floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

 due to processes of erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 of and deposition

Deposition (geology)

Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of...

 on its banks and bars

Bar (river morphology)

A bar in a river is an elevated region of sediment that has been deposited by the flow. Types of bars include mid-channel bars , point bars , and mouth bars...

. In meandering streams

Meander

A meander in general is a bend in a sinuous watercourse. A meander is formed when the moving water in a stream erodes the outer banks and widens its valley. A stream of any volume may assume a meandering course, alternately eroding sediments from the outside of a bend and depositing them on the...

, channel migration typically takes place by erosion of the cut bank and deposition on the point bar

Point bar

A point bar is a depositional feature of streams. Point bars are found in abundance in mature or meandering streams. They are crescent-shaped and located on the inside of a stream bend, being very similar to, though often smaller than towheads, or river islands.Point bars are composed of sediment...

. In braided streams, channel change occurs due to sediment transport

Sediment transport

Sediment transport is the movement of solid particles , typically due to a combination of the force of gravity acting on the sediment, and/or the movement of the fluid in which the sediment is entrained...

 and the motion of barforms

Bar (river morphology)

A bar in a river is an elevated region of sediment that has been deposited by the flow. Types of bars include mid-channel bars , point bars , and mouth bars...

through the channel.

Channel migration is an important engineering problem, as it can undercut and damage transportation infrastructure.