Fig. 1 is a proportional-symbol map from a study of water use in four villages on the edge of the Sahel. Each circle represents daily water collected from a...
Question 1 Report
Fig. 1 is a proportional-symbol map from a study of water use in four villages on the edge of the Sahel. Each circle represents daily water collected from a borehole. The students used household interviews and measured the number of containers carried home. The map is useful for seeing differences between villages, but the class also checked that households had been sampled at each settlement.
(a) State the village with the greatest daily water collection. [1]
(b) Suggest why a proportional-symbol map is more suitable than a simple location map for these data. [2]
A fieldwork notebook contains the flow diagram in Fig. 1. It was produced by students investigating how rainwater moves through an urban catchment after heavy rainfall. They stood at a culvert where water from roofs and roads entered a small stream. The diagram is used to help them distinguish between rapid surface movement and slower underground movement before they analyse discharge data.
(a) State the name given to water flowing over the ground into the stream. [1]
(b) Explain why a paved road is likely to increase this flow during a storm. [2]
Answer Details
Proportional-symbol map
- (a) Kura has the greatest daily water collection because it has the largest circle. [1]
- (b) A proportional-symbol map uses circle size to represent the amount of water collected. It therefore allows differences between villages to be compared quickly while also showing the spatial pattern of water collection. [2]
Urban catchment flow
- (a) Water flowing over the ground into the stream is called surface runoff or overland flow. [1]
- (b) A paved road is impermeable, so little rainwater can infiltrate into the ground. More water therefore travels rapidly across the surface into drains or directly into the stream, increasing surface runoff. [2]
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