Question 1 Report
Table 1 gives measurements from a school investigation of infiltration on two surfaces near a hot desert town in Arizona. Fig. 1 shows the two test plots after the same short rainfall event. Plot A has compacted ground beside a car park, whereas Plot B has loose sandy soil with shrubs.
| Plot | Water infiltrated in 10 minutes (mm) | Surface runoff after 10 minutes (mm) |
|---|---|---|
| A, compacted ground | 2 | 15 |
| B, sandy soil | 11 | 5 |
(a) Which plot has the greater surface runoff? [1]
(b) Outline why compacted ground can increase flash-flood risk. [2]
(c) Draw arrows on Fig. 1 to show surface runoff on Plot A. [2]
(a) Plot A [1] (b) Compaction reduces pore spaces/infiltration [1]; more water flows over the surface quickly into channels [1]. (c) Two arrows downslope/across the compacted Plot A towards a lower edge/channel [2]
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