Changes in River Characteristics
River characteristics
- All rivers have a long profile and cross profiles
- Each river's long and cross profiles are unique but they do have some characteristics in common
- These profiles show changes in river characteristics from the source to the mouth
Long profile
- The long profile of a river shows the changes in the river gradient from the source to the mouth
- Most long profiles have a concave shape with similar characteristics:
- The source is usually in an upland area
- The upper course of the river includes areas which are steep with uneven surfaces
- In the middle course, the gradient decreases
- In the lower section, the gradient decreases further until it becomes almost flat
Long profile
Cross profiles
- The cross profiles of a river are cross-sections from one bank to another
- Cross profiles of the upper, middle and lower courses show the changes in the river channel
- Upper course characteristics include:
- Shallow channel
- Steep valley sides
- Narrow channel
- Low velocity
- Large bedload
- Rough channel bed
- High levels of friction
- Vertical erosion
Upper Course
- Middle course characteristics:
- Deeper than upper course channel
- Gentle valley sides
- Wider than upper course channel
- Greater velocity than upper course channel
- Material in river decreases in size
- Smoother channel bed
- Lower levels of friction than upper course channel
- Lateral erosion
Middle Course
- Lower course characteristics:
- Deeper than middle course channel
- Flat floodplains
- Wider than middle course channel
- Greater velocity than middle course channel (apart from as the river enters the mouth)
- Material carried mainly sediment and alluvium
- Smooth channel bed
- Lowest friction
- Deposition is dominant
Lower Course
Exam Tip
Remember valley shape and river shape are not the same thing. If you are asked to describe valley shape you should focus on the gradient and shape of the land either side of the river channel.
