A river drains water from the land to the sea. In IGCSE Geography you are asked to explain how a river erodes, carries and deposits material, read a channel and a graph, trace its landforms and judge claims about flooding using supplied evidence.
This module sits inside the wider Geography learning guide. It connects well with weather and climate, because rainfall is the input that every river system responds to.
What do you need before you start?
You need to read a table and a simple graph, multiply and divide, find an average and write a sentence of cause and effect. Nothing goes beyond IGCSE-level arithmetic. Check the Cambridge syllabus page for your exam year, because the exact content and skills can change between series.
One orienting example
All numbers in this example are invented for practice. A stream channel is 4 m wide with a mean depth of 0.5 m, and the water moves at 0.6 m/s. The area of the cross-section is 4 × 0.5 = 2.0 m², so discharge is 2.0 × 0.6 = 1.2 m³/s.
After heavy rain, the depth rises to 1.0 m and the velocity to 1.0 m/s. The area is now 4 × 1.0 = 4.0 m², and discharge is 4.0 × 1.0 = 4.0 m³/s.
That is more than three times the earlier figure, since 4.0 ÷ 1.2 ≈ 3.3. Small changes in depth and speed add up quickly, which is why rivers can rise so fast.
Each lesson here repeats the same move: read the numbers, link them to the river’s energy, then explain what follows.
In what order should you study the lessons?
- Explain erosion, transport and deposition through a reach first, because it sets up the idea that energy decides what a river does.
- Interpret a channel cross-section next, because it turns channel shape into area, discharge and efficiency.
- Trace a landform sequence after that, to follow gradient and landforms from source to mouth.
- Read a hydrograph with time lag once you can describe the channel, so you can see how it responds to a storm.
- Evaluate a flood-related claim from supplied evidence last, because it asks you to judge data using everything above.
What are the common traps?
- Naming a process correctly but applying it to the wrong thing, such as attrition for the channel.
- Using maximum depth times width as the cross-sectional area.
- Giving the time of the peak discharge instead of the lag time.
- Placing landforms in the wrong order, for example an oxbow lake before a meander.
- Accepting a flood claim without asking about rainfall, record length and other changes.
How should you use the practice set?
Work through the rivers and drainage practice set with a pencil and calculator, and cover the answers until you have written your own. The statistics and distribution explorer helps with averages, and the food-web and energy-flow explorer is a useful model for thinking about energy moving through a system. Record any repeated slip in the mistake log and retest queue.
Real river case studies are not invented here. When you build notes on one, write down the place, date and source for each fact. Describe events neutrally and factually.
Fieldwork and the alternative-to-fieldwork route are set by your course and exam centre, and the Cambridge page sets out what is assessed. Our online lessons focus on the data and written-answer skills around them, described on the Geography tuition page.