A braided river channel consists of a network of small channels separated by small islands called braid bars.
The channels and braid bars are usually highly mobile, with the river layout often changing significantly during flood events. Channels move sideways via differential velocity: On the outside of a curve, deeper, swift water picks up sediment (usually gravel or larger stones), which is re-deposited in slow-moving water on the inside of a bend.
The most famous example of a large braided stream in the United States is the Platte River in central and western Nebraska. The sediment of the arid Great Plains is augmented by the presence of the nearby Sand Hills region north of the river.
Extensive braided river systems are found in only a few regions world-wide:
Streams receive most of their water input from precipitation, and the amount of precipitation falling in any given drainage basin varies from day to day, year to year, and century to century.
Streams carry most of the water that goes from the land to the sea, and thus are an important part of the water cycle.
Because meandering streams are continually eroding on the outer meander bends and depositing sediment along the inner meander bends, meandering stream channels tend to migrate back and forth across their flood plain.
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