How the long profile changes downstream Flashcards
Long profile
The journey of the river from source to mouth and the changes in the characteristics of the channel
The Bradshaw model
It is a model that shows changes in the characteristics of the river downstream
What is wetted perimeter?
The area of the channel in contact with water
Why is wetted perimeter higher upstream?
Upstream, there are still rocks and boulders in the river
What is discharge?
The amount of water in the river passing a given point at a given time
Unit for discarge
M3/s (CUMECS)
What happens to the velocity and discharge of a river along its course?
They increase
What affects the velocity of a river?
How much water comes into contact with the channel banks and bed
Why is velocity low in the upper course?
There is a lot of friction
Why is there more friction in the upper course?
The channel is shallow and narrow due to vertical erosion, and the valley sides haven’t been widened up much by weathering and erosion due to the harder rock here
Why does the river begin to meander and erode laterally in the middle course?
It flows through lower country where the gradient is less steep
Why does lateral erosion increase in the middle course?
The rocks that make up the valley sides are softer
Why does the river get a more gentle profile in the middle course
It uses more energy in lateral erosion and isn’t able to remove all the eroded material. This builds up on the valley floor to give it a gentle profile
Nature of the channel in the lower course
Very wide and deep
Why is there a higher velocity in the lower course?
The wide, deep channel leads to less friction
