What are the types of river erosion?

There are four main types of river erosion. You can have hydraulic action, attrition, abrasion and solution. 

Hydraulic action is the power that the water has to simply break away bits of the river bed and banks. Attrition happens when rocks that are carried by the river smash into each other and break into smaller rocks. Abrasion is also to do with rocks that are carried by the river but this time instead of smashing into each oher they smash into the river banks and break bits away from the bank. The final type of erosion is solution which is quite different to the other three types. Solution happens when chemical (mainly acids) in the water dissolve rocks and material that is in the river bed and banks.