What are the main forms of river erosion?

Definition: River erosion is a process through which the riverbed, banks and rocks are worn away.

There are 4 key types of river erosion:

1. Attrition
This occurs as smaller rocks which are carried along by the river knock and bounce into each other. This breaks the rocks down into smaller and more smooth and rounded rocks.

2. Abrasion
This occurs as pebbles move and grind along the riverbank and bed. As they scrape along, they cause the riverbed and bank to wear away. This process is like when you sandpaper wood!

3. Solution
This occurs as the water dissolves more alkaline rocks (rocks that dissolve more easily) such as limestone. These rocks are dissolved into the water and then carried along in the water solution.

This also happened to alkaline rocks/rock particles that are in the riverbed and banks. When this happens to the riverbed and banks, the structure of the riverbed and bank is weakened and over time the land will wear away.

4. Hydraulic Action
This occurs as water hits the riverbed and banks. Air becomes trapped in cracks in the rock which expands these cracks causing the rock to wear away.

Remember: These processes all happen at the same time and so it is important to think of them all as part of what goes on in all rivers at all times.



Top Tip: Try making flashcards with the key term on one side and the explanation on the other to help you memorise them!