Pearson Edexcel GCSE (9-1) Geography B (1GB0) · Spec 4.6, 4.7 and 4.8
Rivers: processes, floods and management
Read the notes, then try the questions. Each one is marked the moment you press Check, and shows the right answer and why.
Key ideas
- In the upper course the valley is narrow and V-shaped, with vertical erosion. Downstream the valley is wide and flat with a floodplain. The long profile is steep near the source and gentle near the mouth.
- Rivers erode by hydraulic action, abrasion and attrition. They transport load by traction (boulders rolled), saltation (stones bounced), suspension (fine particles carried) and solution.
- A waterfall forms where hard rock lies over softer rock. The soft rock is undercut and the waterfall retreats upstream, leaving a gorge.
- Flood risk has physical factors, such as heavy rain and steep slopes, and human factors, such as building on the floodplain.
- Hard engineering includes embankments, flood walls and relief channels. Soft engineering includes floodplain zoning and planting trees in the catchment.
Key terms
- Floodplain
- The flat land either side of a river that floods in high water.
- Traction
- Large boulders rolled along the river bed.
- Saltation
- Small stones bounced along the river bed.
- Hydrograph
- A graph of river discharge over time after a rainstorm.
- Floodplain zoning
- Controlling what is built on land that floods.
Common mistakes
- Saying river hard engineering means sea walls and groynes. Those are coastal. Think embankments and flood walls.
- Saying brown water means no sediment load. Fine particles in suspension make the water brown.
- Saying a river is in flood because it looks deep or fast. Flood evidence is water outside the normal channel.
Exam tip
Q3 on Paper 2 is worth about 6 marks. When you explain a cost of hard engineering, develop it: maintenance costs, money taken from other services, damage to habitats or more flooding downstream. Saying it costs a lot earns little.
Free practice questions
7 questions, 15 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.
- Question 1 · Multiple choice[1 mark]
Which describes the typical valley cross profile in the upper course of a river?
- Question 2 · Fill the gaps[2 marks]
Vertical erosion upstream cuts a ___-shaped valley, while downstream the valley has a wide, flat ___.
Word bank: floodplain · V · U
- Question 3 · Matching[3 marks]
Match each river erosion process to its description.
- Question 4 · Put in order[1 mark]
Put the stages of waterfall and gorge formation in order.
Use the arrows to put these in the right order, first at the top.
- 1The soft rock is undercut and a plunge pool forms
- 2Hard rock lies over softer rock
- 3The overhanging hard rock collapses
- 4The waterfall retreats upstream, leaving a gorge
- Question 5 · Choose more than one[2 marks]
Which TWO are soft engineering methods for river flooding?
Choose 2.
- Question 6 · Sort into groups[3 marks]
Sort each flood-risk factor into the correct group.
Deforestation
Impermeable rock
Heavy, prolonged rainfall
- Question 7 · True or false[3 marks]
Decide whether each statement about waterfalls and gorges is true or false.
1. A waterfall retreats upstream as the overhanging hard rock collapses.
2. A gorge forms when a river cuts straight down through rock from above.
3. A plunge pool forms at the foot of a waterfall.