A river profile question asks you to describe what the diagram shows and then explain it with a process. The pattern is simple: upper course erodes vertically, middle course transports, lower course deposits.
This lesson belongs to river processes and sustainable management. Next, connecting a river landform to the process evidence uses the same idea on named landforms.
What does a long profile actually show?
A long profile plots height above sea level against distance from the source. It is usually a concave curve: steep at the start and nearly flat at the mouth.
The steepness is the gradient. Gradient controls how much energy the water has, and energy decides whether the river erodes, carries or drops its load.
Worked example: an invented river in four stations
Below is an original, schematic river. It is not a real river and the numbers are invented for practice.
| Station | Distance from source | Height |
|---|---|---|
| A | 0 km | 900 m |
| B | 20 km | 300 m |
| C | 60 km | 40 m |
| D | 100 km | 5 m |
Work out each gradient as height drop ÷ distance.
- A to B: (900 − 300) ÷ 20 = 600 ÷ 20 = 30 m per km
- B to C: (300 − 40) ÷ 40 = 260 ÷ 40 = 6.5 m per km
- C to D: (40 − 5) ÷ 40 = 35 ÷ 40 = 0.875 m per km, about 0.9 m per km
Turning the figures into an explanation
Use three parts: claim, evidence, reason. Here is a model for A to B.
Claim: vertical erosion dominates between A and B. Evidence: the river falls 600 m in 20 km, a gradient of 30 m per km, the steepest section. Reason: the steep slope gives fast flow and high energy, so hydraulic action and abrasion by coarse stones cut the valley floor downward.
For C to D the same pattern reverses. The gradient is under 1 m per km, so velocity falls, the river loses energy and deposits silt. That explains why a floodplain forms near the mouth.
The mistake that costs marks
The common slip is to write a memorised paragraph about the three courses without using the stations. The answer is true but never touches the diagram, so the evidence mark is lost.
| Weak | Stronger |
|---|---|
| “The upper course has erosion.” | “Between A and B the gradient is 30 m per km, so erosion is vertical.” |
| “Deposition happens at the end.” | “Between C and D the gradient is 0.9 m per km, so energy is low and silt is deposited.” |
| “The river carries material.” | “Between B and C the gradient eases to 6.5 m per km, so the river transports its load and begins to cut sideways.” |
Check yourself
An invented river has P at 1 200 m (0 km), Q at 600 m (15 km) and R at 100 m (55 km). Find both gradients and say which section is dominated by vertical erosion.
Answer
P to Q: (1 200 − 600) ÷ 15 = 600 ÷ 15 = 40 m per km.
Q to R: (600 − 100) ÷ 40 = 500 ÷ 40 = 12.5 m per km. The distance is 55 − 15 = 40 km.
P to Q is steeper, so vertical erosion dominates there. The high energy lets the river cut downward and move coarse, angular stones. Q to R is gentler, so the river shifts toward transport and lateral erosion.
What to study next
Move on to connecting a river landform to the process evidence, then try the river processes practice set. The graph evidence and fair-comparison lab lets you practise comparing sections from data.
If you want a teacher to go through your own profile answers, see online one-to-one Geography tuition.