River profiles

Question 1

Long profile?

Answer 1

A line that shows the course of a river from the source (where it starts) to the mouth (where it meets the sea).

Question 2

Cross profile?

Answer 2

Shows a cross-section of a river’s channel and valley at a certain point along the river course.

Question 3

Upper course?

Answer 3

• Mainly hydraulic action and attrition
• Vertical erosion as there is greatest amount of G.P.E
• Some traction and saltation at a high flow
• Shallow, narrow channel
• Waterfalls, interlocking spurs
• Deposition of a large material
• Lots of friction due to large bedload
• Steep sided V-SHAPED valley

Question 4

Middle course?

Answer 4

• Some vertical erosion but lateral erosion more important hydraulic action less important
• Suspension is the main transportation and saltation and traction are still present
• Valley, meanders, slip off slopes, river cliffs, ox-bow lakes, floodplains
• Deposition more obvious as ox bow lakes form
• Wider more U-SHAPED

Question 5

Lower course?

Answer 5

• Less erosion, only a little lateral, erosion much less important
• Largest amount of load and sediment is now very small as it has been eroded away
• Suspension dominates
• The river banks and bed are really smooth
• The river is carrying a large volume of water
• Deposition of fine light material called alluvium
• River is flowing the fastest
• WIDEST and DEEPEST channel and valley

Question 6

Describe and explain how the valley cross profile changes downstream. (6 marks)

Answer 6

The cross profile is v shaped in the upper course. This is because the river has more gravitational potential energy and cuts vertically through the land.

As the river moves downstream into the middle course it erodes laterally so the river becomes more wider and U shaped.

As the river carries most of the water in the lower course it becomes very wide and deep.