Rivers meander when they are traveling on top of a relatively flat surface.

•Meander is a result of friction between the stream and its bed. The pattern of flow that dissipates the stream’s energy most rapidly is a meandering helical pattern.

•The meander pattern shifts constantly since the river is cutting the bank on the outside of meander loops and depositing alluvial sediment on the inside.

The pattern of flow in rivers and streams creates a diversity of habitatsboth within the stream and on the floodplain.

meandersIn streams and rivers of different sizes

http://www.kented.org.uk/ngfl/rivers/River%20Articles/meander.htm

Streams flow down hill and take the path of least resistance, however the path is usually a meandering instead of straight

It takes more velocity to suspend and move larger particles

Oxbow lake forming from a river meander

The erosion that occurs during a flood even may cause the river to take a shortcut from one loop to the next--thus cutoff loop will remain as an oxbow lake.

Oxbow lakes and braided channels on the Upper Amazon River

http://muller.lbl.gov/travel_photos/AmazonWebPages/AmazonWebPages-Thumbnails/1.jpg

http://waterknowledge.colostate.edu/meander.htm

An important reference on River MeandersLeopold, L.B., and M.G. Wolman, 1960,River Meanders: Geol. Soc. America, Bull., v. 71, pp. 769-794.

The physical stresses on the river bed during floods often cause a river to change course.

The river valley contains many old channels superimposed on each other

A good example of braiding in the river channel

Rivers often simultaneously occupy several of their historical channels at once.We call this type of river channel braided

Oldman RBelow Summerview

Showing old river channels

When rivers cut deeply into the landscape the meander pattern becomes entrenched and from then on shifts downward only.

http://courses.missouristate.edu/EMantei/creative/WeathStrem/entrenched.jpg

If you want to learn more about the landforms and deposits created by running water, with particular reference to western Canadian watersheds, take

Geography 3035Fluvial Geomorphology—Hester Jiskoot

Other courses of relevence are

Geography 4015Integrated Watershed Management—Jim Byrne

AndGeography 4012Hydrology—Stefan Kienzle