Braided River. Image credit patternsofthefuture.com

Braided River. Image credit patternsofthefuture.com

ZIMSEC O Level Geography Notes: Braiding and Alluvial Fans

Braiding

  • Braiding occurs typically during the dry season when a river’s discharge is greatly reduced.
  • The river may be split into several channels which rejoin and split again.
  • These are known as braided river channels.
  • Rivers with heavy loads becomes overloaded in the dry season when the amount of water falls in the dry seasons.
  • As the amount of water and thus its capacity to carry the load is reduced deposition takes place in the form of sand banks and alluvium islands causing a channel to braid.
  • In order to continue flowing the river splits into smaller channels that continuously split and rejoin.
  • Braiding is the process by which a river diverges and ¬†converges into a series of segments separated by channel bars
  • A braided river can be both wide and shallow.
  • Although it mostly occurs in the floodplain braiding is by no means limited there.
  • Human activities such as streambank cultivation and gold panning can lead to the choking of the river due to excessive siltation and thus result in braiding.
  • Decreased discharge in Winter months leads to river braiding in most of Southern Africa’s rivers including Zimbabwe.
A braided river channel. Image credit Uwec.edu

A braided river channel. Image credit Uwec.edu

Alluvial Fans

A vast 60km alluvial fan in China. Image credit WikiMedia

A vast 60km alluvial fan in China. Image credit WikiMedia

  • These are cone or fan shaped features composed of alluvium that form as a tributary descends down the bluffs onto the flood plain.
  • Deposition occurs at the point where the steep bluff merges with a flat plain leading to reduced velocity.
  • They also occur when a river descends into a flat area from an escarpment or the edge of a rift valley.

To view more landforms formed by river processes go to this page.

To access more topics go to the Geography Notes page.


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