Explain processes of erosion that occur in a river

The first erosional process that occurs in a river is hydralic action, which is where water is forced into cracks in the river bed and channel which compresses trapped air, making the cracks larger which can cause material to chip away and fall off. The next type is abrasion, which occurs when rocks and bedload is carried by the river and wears down the river channel. Attrition is the process of the river bedload smashing into one another which wears down the bedload into smaller pieces. Corrosion is the process of soluable particles in the river being dissolved by acicid substances.