River Processes

There are 3 river processes that occur as the river flows along its course.

1) Erosion
occurs when rocks and other materials are broken into smaller pieces and moved downstream by the energy of the river.

The four processes of erosion are:

• Hydraulic action where fast-moving water loosens and dislodges the rocks and soil from river bed and banks.
• Corrasion where rock fragments that are dragged along by the flow of the river, grind against the river bed and banks.
• Attrition where eroded materials in the river constantly collide against each other and break down into smaller pieces.
• Solution where minerals in the rock dissolve in the carbonic acid in the river due to acid rain.

To remember:
" I was a piece of rock by the river bank, broken off by hydraulic action. I was carried by the river causing corrasion as I erode the river bed and banks. I collide against the other rocks, resulting in attrition. I’m going to be dissolved in solution as there’s carbonic acid in the water. "

(By student: Hot Chicks Affect Success)

2) Transportation
occurs when materials are carried downstream by the energy of the river.

The four processes of transportation are:

• Traction where the larger size materials are rolled and slided along the river bed. (e.g boulders and gravel)
• Saltation where materals are transported downstream in a series of bouncing action. (e.g. coarse sand)
• Suspension where fine particles are carried along in the river without touching the river bed. (e.g. silt and clay)
• Solution where the river transport dissolved materials downstream. (e.g. calcium carbonate)

The following webpage shows an animation of how the river transports its load.
http://www.school-portal.co.uk/GroupDownloadFile.asp?file=21393

To remember:
" There was a tractor (traction) bringing soil to the construction site. However the salt (saltation) content of the soil is too high. The driver got a suspension and has to think of a solution as he lost his rice bowl. "

(By student: Think Some Sexy Stuff)

3) Deposition
occurs when the river puts down or deposits its load due to insufficient energy.