How does a river erode?

Answer 1

rivers aren't permanently the same shape, through different methods rivers can be eroded and shaped over long periods of time. i will give four

Hydraulic action, this is where the sheer force of the water forces the river side to be eaten away, this can be through cracks in rock or mud which the water is forced into which can then break off fragments.

Attrition, this is where large objects such as mud or rocks smash together and break of fragments.

Abrasion, this is where particulates such as sand or small stones are carried by the river and rubbed on the river walls, this works much like sandpaper and grinds away the river

corrosion, this is where chemical substances in the water that are particularly caustic react and dissolve river walls and other substances

Answer 2

river beds are eroded because the four main types of erosion,attrition,abrasion,corrosion and hydraulic action slowly break away the rocks that are found on the river bed. Therefore as more rocks are eroded/transported off the bottom of the river bed, the river will effectively become deeper. This method also applies for channel width

Answer 3

a steam is eroded when water passes by through the years.

Answer 4

Yes, they erode their banks and fill in the channels also.

Answer 5

it don't.