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Earth and Space Sciences · Glossary

What is Braided and meandering rivers?

Also known as: braided river · meandering river · point bar · avulsion

Definition 17.4 University Earth and Space Sciences — Year 3 · Chapter 17 — Facies Models

A braided river flows in several shallow channels that divide and rejoin around bars, on a steep plain with abundant coarse load and variable discharge. A meandering river flows in a single sinuous channel on a gentler plain, carrying more fine sediment; it migrates by eroding the outer bank of each bend and depositing on the inner one. The deposit on the inner bank is a point bar. Avulsion is the abandonment of a channel for a new course across the floodplain, usually after a flood breaches a levee.

(a) A braided river: several channels around bars of sand and gravel. (b) A meandering river: one sinuous channel, point bars (pb) on the inner banks, an abandoned course (dashed) left by avulsion. Right: grain-size logs of the deposits (width means coarser): stacked sand sheets with little change upward for the braided river, a sharp-based fining-upward succession capped by rooted floodplain mud for the point bar.
(a) A braided river: several channels around bars of sand and gravel. (b) A meandering river: one sinuous channel, point bars (pb) on the inner banks, an abandoned course (dashed) left by avulsion. Right: grain-size logs of the deposits (width means coarser): stacked sand sheets with little change upward for the braided river, a sharp-based fining-upward succession capped by rooted floodplain mud for the point bar.
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