Why does bedload decrease in size downstream? Watch

becky96
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I know it's to do with attrition and abrasion but why does that happen?? If the river is gaining more energy for it to be doing these processes why does it deposit more bedload downstream?


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A is for Alice
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Hey, I've just been doing rivers in geography so I'll try to explain it.

Bedload size decreases downstream because as the river moves down stream it's velocity increases. As the velocity increases, it allows the river to pick up heavier and larger sediment, this sediment will bump into each other and into the river bank causing bits to break off (attrition and abrasion). By the time the river's reached it's lower course, the sediment that was once large will have been broken into smaller pieces of sediment and become more smooth and rounded from rubbing against other sediment.
The river will drop most of it's bedload when it reaches it's mouth (usually the sea) because of the sudden change in velocity, from high velocity to low velocity.

Hope this helps
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ConnorMckay
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Bye Bae.
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Hollydp143
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Why does the velocity increase? Thanks
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izzyll
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(Original post by Hollydp143)
Why does the velocity increase? Thanks
Because depth and width are increased; the velocity will become higher if there is a constant supply/flow of water. :-)
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Mina_
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(Original post by Hollydp143)
Why does the velocity increase? Thanks
There is more tributaries entering the river leading to a rise in discharge and velocity
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RandomChick
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Oh my days same bro
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lokuy
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Yh that's right
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lokuy
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(Original post by lokuy)
Yh that's right
Check out the Bradshaw model... might help but it's very generic
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Cat9cherry
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#10
Bradshaw model is
Velocity increases between the source and mouth of the river, the bedload size and shape is large at the source and get smaller towards the mouth. The cross sectional area increases towards the mouth. Discharge is the amount of water
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Karrie04
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Thanks helped a lot!!
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