What Are Meanders?
Meanders are a winding curve or bend in a river.
Where Do Meanders Occur?
Meanders can occur in the middle or lower course of a river.
How Are Meanders Formed?
Meanders are formed by Deposition and Erosion.
Decribe and Explain how a Meander is formed
On the outside of a meander the fast flow of water leads to erosion on the outside bank. the power of the water erodes the bank. This is known as hydraulic action. The load being carried by the river hits the bank, erodes and undercuts it. The material above collapses and leaves a steep side called a river cliff.
On the inside bend, the slow flow of water cannot erode and deposition is the dominant process. In the slow flowing water, material is deposited to form a steep slope.
Ariel View of a Meander
Difference between the inside + outside of a river
The inside of a river is shallow. This part of the river also has a beach (slip off slope).
The outside of a river is quite deep. This part of the river also has a river cliff.
Explain why these contrasts occur
The inside of a river has a slow flow, and Deposition occurs.
The outside of a river has a fast flow, and Erosion occurs. This type of Erosion is called Hydraulic Action.
What Are Oxbow Lakes?
An Oxbow lake is a horseshoe shape. It is a bend in a river - where the main stream has cut across and no longer flows around the bend.
Where Do Oxbow Lakes Occur?
Oxbow Lakes can occur in the middle or lower course of a river.
How Are Oxbow Lakes Formed?
Oxbow Lakes are formed by Erosion and Deposition.
Describe and Explain how an Oxbow Lake is formed
The river begins to meander. The fastest flow is on the outside bend and the slowest flow is on the inside bend.
The fastest flow is on the outside bend, which results in Erosion on the side of the channel. The slower water is on the inside bend which causes Deposition.
This causes the meander to shift (migrate) and the two outside bends get closer together. As these processes continue, it creates a small area of land separating the neck of the meander. This is broken through, often in flood.
The river follows the shortest course, which leaves an Oxbow Lake without a water supply.
Deposition continues until the Oxbow Lake becomes marshy.