When a river bends and twists, what is it called?

Answer

The bending and twisting of river is called as meandering.

Meandering river are basically asymmetric.

There are two theories which explain the formation of meandering. these are as follow:

1. stochastic theory

Formation due to obstacles to the flow of river.

2. Equilibrium theory

Formation due to equilibrium between erodibilty of land and transport capacity of stream.