As the river enters the plain it twists and turns forming large bends known as ______.

The correct answer is meanders.

Key Points

• Meandering River:
  • The formation of successive bends of reverse order may lead to the formation of a complete S curve called Meanders.
  • When consecutive curves of reverse order connected with short straight reaches called crossings are developed in a river reach, the river is stated to be a Meandering river.
• The meandering of a river is due to the erodibility of the bed and banks of streams.
• Causes
  • Extra turbulence is generated by excess river sediment during floods. When the silt charge is in excess of the quantity required for stability, the river starts building up its slope by depositing the silt on its bed.
  • The increase in bed slope tends to increase the width of the channel if the banks are not resistant. The banks are attacked by river water and in the process one bank is likely to be attacked slightly more than the other, causing a slight deviation in flow.
  • This slight deviation from the uniform axial flow helps in improving more and more flow towards one bank than towards the other.
  • This process continues causing one bank to be convex and another to be concave. Hence, increasing slope is also a reason for meandering.

Additional Information

• Meander parameters:
• Meander Length: It is the axial length of one mender, i.e. tangential distance between the corresponding points of the meander.
• Meander Belt: It is the distance between the outer edges of clockwise and anticlockwise loops.
• Meander Ratio: It is the ratio of the meander belt to the meander length.
• Tortuosity: It is the ratio of length along the channel (actual length) to the direct axial length.
• Crossings or cross-over: It is the shortest reach of the river, connecting two consecutive clockwise and anticlockwise loops.