L3 - Changing Course

Question 1

How long is the River Severn and where is it geographically located?

Answer 1

UK’s longest river at 354km

Rises in mid-Wales, flows east into England and then south into the Bristol channel

Question 2

How does the gradient develop with the River Severn?

Answer 2

Upper course - steep, V-shaped valleys and interlocking spurs present
Middle course- flatter, still fairly steep, meanders and ox-bow lakes form
Lower course - flat, deltas, levees, flood plains

Question 3

What is discharge?

Answer 3

The volume of water that passes through a cross-section per unit time
Measured in cumecs (cubic metres per second)
Increases the further downstream

Question 4

Describe features of the upper course in the River Severn.

Answer 4

Geology - hard rock (impermeable shale and grit)
Near the river source (Plynlimon 610m above sea level) - narrow and shallow channel, angular stones slowing river down due to friction

Question 5

Describe features of the middle course in the River Severn.

Answer 5

Softer, permeable rock - sandstone

Wider and deeper due to erosion, velocity increases

Question 6

Describe features of the lower course in the River Severn.

Answer 6

Geology - mudstone, sand, gravel

- River channel widens, discharge increases

Question 7

What happens to discharge downstream?

Answer 7

Increases
More tributaries join the river draining a larger catchment area increasing the volume of water.
- Channel width is greater due to erosion further up the course, gradient decreases and width increases faster than depth.

Question 8

What happens to river velocity downstream?

Answer 8

Increases

River is smoother and larger due to previous erosion, reducing friction and gradient

Question 9

What happens to gradient downstream?

Answer 9

In the River Severn the gradient decreases
- Weaker rock has already been eroded along the middle and lower courses, more resistant rock upland so gradient remains high,