Answer one question from this section. (a) Study Fig. 3.1, a flood hydrograph of a river after heavy rainfall. Content removed due to copyright restrictions [Figure 3.1]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2025). The mark or mark type is shown in brackets.

1. [1] 55 (cumecs)
2. [1] Overland flow: Water which flows across the land/on top of the land/runs off the surface/ surface run off/over the surface.
3. [1] Throughflow: Water which flows through/within the soil
4. [1] Rain does not land directly on river/channel/rain has to move to river from other areas/higher land in the drainage basin;
5. [1] Rain could be intercepted by vegetation;
6. [1] Water moves from tributaries/smaller streams to main river;
7. [1] Overland flow/surface runoff/flowing across the surface;
8. [1] Infiltration occurs/throughflow/water flowing through the soil;
9. [1] Percolation occurs/groundwater flow/baseflow/water flowing through the rock/underground;
10. [1] Deforestation along the valley sides: Increases discharge/more water in river/deeper/faster flow/floods/peak discharge is sooner/shortens lag time;
11. [1] More surface runoff/ less infiltration;
12. [1] As rainfall is not intercepted by trees/used by trees/water is not taken up by roots/less transpiration;
13. [1] Surfaces/soil becomes more compacted/less permeable/makes movement of water more rapid; Etc.
14. [1] Building a large reservoir close to the river's source: Reduces/regulates discharge/less water/shallower/slower flow/prevents flooding/delays peak discharge/increases lag time;
15. [1] As natural flow is prevented/water held back/stored by dam;
16. [1] Water is transferred out of drainage basin so does not flow down the river etc
17. [1] X is a slip off slope but Y is a (river) cliff;
18. [1] X is gently sloping/flatter but Y is steep/steeper/vertical;
19. [1] X is pebbles/rocks/stones/material at X is smaller but Y is a bank made of sand/soil/material at X is larger;
20. [1] X is low but Y is high/Y is higher, etc.:
21. Note: Accept left and right/inner and outer as alternative to X and Y
22. Note: Comparison needed
23. [1] River flows around a meander/on a meander/bend/curve;
24. [1] Helicoidal flow;
25. [1] Erosion on outer bank/at Y/right bank;
26. [1] Fast(er) flow/high(er) energy on outer bend/at Y or slow(er) flow/low(er) energy on inside bend/at X;
27. [1] Hydraulic action/abrasion (or description of process);
28. [1] Deposition on inside bank/at X/at left bank; Etc.
29. Levels marking
30. Level 1 (1–3 marks): Statements including limited detail which explains how a waterfall is formed.
31. Level 2 (4–6 marks): More developed or linked statements which explain how a waterfall is formed.
32. Level 3 (7 marks): Comprehensive and accurate answer, which explains how a waterfall is formed and includes a labelled diagram
33. Content Guide: Answers are likely to refer to: Hard rock overlies soft rock
34. Erosion of softer layer by river
35. Abrasion/hydraulic action
36. Undercutting
37. Overhang
38. Formation/deepening of plunge pool
39. Hard rock unsupported
40. Collapse of hard rock layers
41. Retreat of waterfall
42. Gorge formation Etc.