Fig. 1 shows a spit at the entrance to a tidal river in northern Spain. A geography class used an aerial photograph and a map to trace the curve of the spit...
Question 1 Report
Fig. 1 shows a spit at the entrance to a tidal river in northern Spain. A geography class used an aerial photograph and a map to trace the curve of the spit. Salt-tolerant grasses grow in the sheltered water behind it, while waves from the open sea strike the seaward side. The students are investigating how deposition has changed the shape of this coastal landscape.
(a) State the name of the sheltered water feature behind the spit. [1]
(b) Explain why the end of a spit may be curved. [2]
The table below shows wave data recorded by an automatic buoy off the coast of Cornwall. Fig. 1 shows a wave approaching shallow water near the shore. The data were used in a coastal study to decide when students could safely measure sediment size on the beach. Wave height was measured from crest to trough.
| Time | Wave height (m) | Wave frequency (waves per minute) |
|---|---|---|
| 09:00 | 0.4 | 7 |
| 12:00 | 1.1 | 12 |
| 15:00 | 1.8 | 16 |
(a) State the wave height at 12:00. [1]
(b) State whether wave frequency increased or decreased during the study. [1]
(c) Suggest why waves become higher as they enter shallow water. [2]
Answer Details
Spit
(a) The sheltered water behind the spit is a lagoon. [1]
(b) Longshore drift deposits sediment along the coast to build the spit. A change in wind or wave direction, or the influence of a river current at the estuary, can make deposition bend inland, producing a curved or recurved tip. [2]
Wave data
(a) The wave height at 12:00 was 1.1 m. [1]
(b) Wave frequency increased, from 7 to 16 waves per minute. [1]
(c) In shallow water, friction with the sea bed slows the base of the wave. Water behind continues to arrive, so it piles up; the wave becomes steeper and higher before breaking. [2]
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