Avulsion (river)

Deposition from the river results in the formation of an individual deltaic lobe that pushes out into the sea.

An example of a deltaic lobe is the bird's-foot delta of the Mississippi River, pictured at right with its sediment plumes.

If the river could breach its natural levees (i.e., during a flood), it would spill out onto a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope.

This will make it easier for the river to breach its levees and cut a new channel that enters the ocean at a steeper slope.

When these channel switching events happen repeatedly over time, a mature delta will gain a distributary network.

[7][8] Rivers can also avulse due to the erosion of a new channel that creates a straighter path through the landscape.

[1] Avulsion typically occurs during large floods which carry the power necessary to rapidly change the landscape.

[13] Avulsions have been investigated in deltas or coastal plain channels as a result of obstructions such as log-jams and possible tectonic influences.

Plumes of sediment enter the ocean from several mouths of the Mississippi River bird's-foot delta . This sediment is responsible for building the delta and allowing it to advance into the sea. As it extends further offshore, the channel slope will decrease and its bed will aggrade , promoting an avulsion.