River Processes
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Aims:
To understand how rivers transport material.
Erosion- Attrition, hydraulic action, carrasion, corrosion.
Deposition.
Resources
Waugh P.282
Internet s-cool.co.uk/geography
Activities
Energy is needed in any system (not just drainage basins) for transfers to take place.
Under normal conditions 95 % of a river’s energy is used to overcome friction.
Most friction occurs at the wetted perimeter
The wetted perimeter is where the river comes into contact with the surrounding banks and bed.
Erosion
4 types of river erosion
Attrition – This is the process whereby the river moves boulders and rocks that collide into each other and break into smaller pieces. Most attrition occurs near the source of the river- in its upper reaches
Hydraulic Action- This is where the water forces air into small cracks in the side of the river bed. The air is under pressure, when it escapes, a small explosion occurs, breaking of some eroded material
Corrasion- Smaller material carried in the river stream rubs the bank and bed of the river making it smoother and more eroded
Corrosion- Acids in the water dissolve the river banks and bed.
4 processes of transpiration
Intraction: Big rocks roll along the river
Saltation; When rocks jump over the river bed
Suspension: Small rocks are carried within the water flow
Solution: The rocks are totally disolved
About the Author
by: Admin
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Word Count: 659
Date: Sun, 13 Feb 2011 Time: 4:38 PM
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