Table 1 shows observations from a study of sand dunes behind a beach in Northumberland. Fig. 1 shows the route used by students, who placed a 1 metre quadra...
Question 1 Report
Table 1 shows observations from a study of sand dunes behind a beach in Northumberland. Fig. 1 shows the route used by students, who placed a 1 metre quadrat at regular intervals from the strandline towards older dunes. They recorded plant cover and measured the height of each dune using a tape and ranging pole. The fieldwork was completed without walking on areas of bare, unstable sand.
| Distance from strandline (m) | Plant cover (%) | Dune height (m) |
|---|---|---|
| 5 | 8 | 0.4 |
| 25 | 32 | 1.3 |
| 45 | 68 | 3.0 |
(a) State the plant cover at 25 metres. [1]
(b) State the trend in dune height shown by Table 1. [1]
(c) Suggest why plant cover increases away from the strandline. [2]
Fig. 1 shows a simple sediment budget diagram prepared for a shingle beach at Lyme Regis, England. Material enters the study area from a river and from longshore drift. Sediment leaves when waves carry it beyond the eastern boundary and when council workers remove shingle for harbour maintenance. The diagram is used to help predict whether the beach will become narrower over time.
(a) State one source of sediment entering the beach system shown in Fig. 1. [1]
(b) Explain why a negative sediment budget may increase the risk of coastal erosion. [2]
Answer Details
Sand dunes
(a) Plant cover at 25 m is 32%. [1]
(b) Dune height increases with distance from the strandline, rising from 0.4 m at 5 m to 3.0 m at 45 m. [1]
(c) Further inland there is less salt spray and wave disturbance, so the sand is more stable. Plants can establish roots and trap additional sand, increasing plant cover still further. [2]
Sediment budget
(a) One source of sediment is the river. Longshore drift is also a valid source. [1]
(b) A negative sediment budget means more sediment leaves the beach system than enters it. The beach becomes narrower and absorbs less wave energy, allowing waves to erode the coast more strongly. [2]
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