changing channel characteristics

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what is cross profile
shows a slice across the river at a certain point- so shows the shape of the river channel and the valley profile
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how does cross profile change downstream
as you go downstream the cross profile becomes wider and steeper, the valley sides become flatter
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why does the cross profile change downstream
this is due to the increase in discharge as more tributaries join the main channel crates a wider and deeper river. // there is also increased lateral erosion do to and increase in kinetic energy and the river is closer to sea level
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what is wetted perimeter
the amount of bed and banks (of the river) in contact with the rivers water
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how does wetted perimeter change downstream
as you go further downstream there is a larger wetted perimeter
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why does wetted perimeter change downstream
this is because the river bed becomes wider and deeper meaning there is more bed and banks in contact with the water
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what if efficiency/ hydraulic radius
efficiency is the energy availible for erosion and transportation // hydraulic radius is the channel's cross section divided by the length of the wetted perimeter
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how does efficiency/ hydraulic radius change downstream
as you go downstream the hydraulic radius increases and the river becomes more efficient
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why does efficiency/ hydraulic radius change downstream
this is because a smaller % of water is in contact with the bed and the banks meaning less energy is used to overcome friction
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what is channel roughness
how angular the bed load is
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how does channel roughness change downstream
it is greater in the upper course of the river and the lower stages are smoother
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why does channel roughness change downstream
as you go downstream erosion means the rocks and banks become much smoother leading to lower roughness
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Card 2

Front

how does cross profile change downstream

Back

as you go downstream the cross profile becomes wider and steeper, the valley sides become flatter

Card 3

Front

why does the cross profile change downstream

Back

Preview of the front of card 3

Card 4

Front

what is wetted perimeter

Back

Preview of the front of card 4

Card 5

Front

how does wetted perimeter change downstream

Back

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