Lesson 9: Formation of an Ox-Bow Lake

A river meanders across the valley eroding laterally(1)

Water directed at the outside of the bend has reduced friction and increased velocity(1).

The faster-flowing water erodes through Hydraulic action(1) when air is compressed into the river bank causing materials to be dislodged(1) and Abrasion(1), pieces of broken-off rock thrown at the river bank causing erosion(1).

There is less water on the inside bend, so less energy means the material is deposited creating a river beach. (1)

Over time continued erosion and deposition narrow the neck of the meander. (1)

During a time of peak discharge (during a flood), the river will break through the neck continuing on a straight path(1), abandoning the meander.

The fastest current is now in the centre of the straight channel and deposition will occur at the side of the river banks. (1)

This deposition will seal off the ends of the meander leaving Oxbow Lake (1). This will eventually dry up and disappear except during times of heavy rainfall or flooding.