(i) Describe the changes in flood frequency shown on the graph.

(ii) Estimate how many more floods occurred in the 1990s than in the 1930s.

Suggest one physical reason and one human reason why the risk of a river flooding can change over time.

To what extent are floodplain landforms the result of river deposition?

(i) Possibilities include:

• increasing number of floods [1]
• appears to be cyclical [1]
• there are two flood-rich periods (1940s to 1960s; 1980s to 2000s) [1]
• one/two flood-poor periods (1900s to 1940s; possibly 1970s) [1].

If no quantification, maximum [2].

[3 marks]

(ii) 31 [1]

Allow answers between 29 and 33 [1].

[1 mark]

Award [1] for each valid reason and [2] for development/explanation/exemplification.

Physical reasons (over different timescales) include more rainfall/storms, climate change, antecedent conditions. Human reasons include deforestation/reforestation, increase in urbanization, climate change, change in agricultural practices, river management, increased monitoring.

For example: An increase in building/urban areas leads to more impermeable [1] surfaces which leads to more surface run-off [1] and a greater amount of water entering the river [1].

For example: Very intense rainstorms [1] caused by low pressure systems/strong monsoonal winds/La Niña, etc, [1] create flooding as river channels are unable to cope with increased water [1].

[6 marks]

Deposition on floodplains does help explain the majority of landforms, but some are explained by a combination of erosion and deposition.

A number of various landforms should be looked at and explained. Responses are not expected to give detailed accounts of the formation of each feature but the contribution of deposition and erosion (as required) should be made clear. Not all features are expected to be covered.

Features include meanders, oxbow lakes, river terraces (formed by both erosion and deposition) and floodplains, braiding, levees, point bars and deltas (depositional only).

Good answers may be carefully structured around mainly depositional landforms and landforms formed by other processes, eg erosion or mass movement. Some might consider the extent to which both erosion and deposition contribute to a particular landform, eg meanders, or are of varying importance at different times, eg seasons or longer-term change, or places.

Do not credit landforms found outside the floodplain area, eg waterfalls.

At band D, expect a number of features to be described but mainly attributed to deposition.

At band E, expect either an explanation of a number of features attributed to erosion/deposition or a combination of the two or a discussion of the extent to which deposition dominates.

At band F, expect both.

Marks should be allocated according to the markbands.

[10 marks]