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

Alluvial Fans

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.