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S5 Geography | Coastal Landforms Paper 4 (Error Retry)
S5 Geography | Coastal Landforms Paper 4 (Error Retry)
Paper 4 targets the marks most often lost: comparing height without period, forgetting the safety margin in cliff retreat, comparing defences by total cost, and reading a wider platform as deposition.
Attempt first, mark afterwards Allow about twenty-five minutes; write the formula and unit before substituting, split any “how much more”, “used up” or “left” question into two steps, and check the direction of the answer at the end.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 items |
| Suggested time | About 25 minutes |
| Difficulty mix | Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1 |
| Chapter | Chapter: S5 Geography | Coastal Landforms |
| Level | S5 (Secondary 5) Geography |
02 Questions (10 items)
- FoundationTwo swells reach the same bay: swell A is 1.2 m high with a 5 s period, swell B is 2.4 m with a 10 s period. Wave energy goes as height squared times period. How many times more energy does B carry?
- FoundationA cliff stands 36 m from a coastal road and retreats 0.6 m a year on average. Guidance requires a 12 m margin from the cliff edge, so in how many years does the road enter the alert zone?
- FoundationLongshore drift supplies 7,500 cubic metres a year and a spit is 600 m long, 50 m wide and 2 m thick on average. How many years of drift does the spit represent?
- FoundationThe roof of a sea arch stands 14 m above the sea and is lowered by 0.2 m a year. How high is the roof above the sea after 30 years?
- IntermediateA bay gains 18,000 cubic metres of sediment a year but loses 7,000 offshore, 4,500 to dredging and 5,000 to longshore output. What is the net budget, and by how much does it change if dredging rises to 7,500 cubic metres?
- IntermediateA sea wall costs $48,000,000, runs 1500 m and lasts 40 years. Nourishment places 18,000 cubic metres at $25 each every 5 years over the same 1500 m. What is each cost per metre per year, and how many times dearer is the wall?
- IntermediateDesign still water level is 2.6 m, storm surge adds 0.9 m and wave run-up 1.5 m. The existing wall crest is 4.2 m. What crest is needed, and by how much is the wall short?
- ChallengeSea level rises 5 mm a year on a shore of slope 1 in 60, while the cliff retreats 0.2 m a year. How far inland does the shoreline move in 60 years?
- ChallengeA groyne traps 9,000 cubic metres a year that used to drift downdrift, where 12,000 cubic metres a year is needed. The downdrift beach has 15,000 cubic metres of buffer. When is it used up, and how much accumulates updrift in the same time?
- Error redoA student sees a wave-cut platform widen from 8 m to 20 m and concludes that the coast is building up and the beach is improving. What is wrong, and how far did the cliff foot move?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | B carries 8 times the energy of A. | 2.4 squared times 10 is 57.6, while 1.2 squared times 5 is 7.2, so the ratio is 8; doubling height quadruples energy and doubling the period doubles it again, which is why height alone understates it. |
| 2 | In about 40 years. | The usable retreat is 36 minus 12, or 24 m, and dividing by 0.6 gives 40 years; only the distance down to the margin counts. |
| 3 | About 8 years. | The spit holds 600 times 50 times 2, which is 60,000 cubic metres, and dividing by 7,500 gives 8 years; its curved end records the drift direction. |
| 4 | About 8 m. | 0.2 times 30 is 6 m, and 14 minus that leaves 8 m; once the roof reaches sea level it collapses and the piers become stacks. |
| 5 | The net is now +1,500 cubic metres; with the extra dredging it is -1,500, a change of 3,000 cubic metres. | 18,000 minus 7,000, 4,500 and 5,000 leaves 1,500; replacing the dredging figure with 7,500 gives -1,500, so the budget falls by 3,000 and turns negative, which is when a beach starts to narrow year after year. |
| 6 | The wall costs $800 per metre a year and nourishment $60; the wall is about 13.33 times dearer. | The wall is $48,000,000 divided by 1500 and by 40, or $800; one nourishment is 18,000 times $25, or $450,000, and dividing by 5 and 1500 gives $60, so the ratio is 13.33. |
| 7 | A crest of 5 m is needed, so the wall is 0.8 m short. | 2.6 plus 0.9 plus 1.5 is 5 m, and taking away 4.2 leaves 0.8 m; the three terms add because surge and run-up occur together. |
| 8 | About 30 m. | 5 mm times 60 is 300 mm, or 0.3 m; times 60 gives 18 m, the cliff adds 0.2 times 60, or 12 m, and the two add to 30 m because both push the shoreline the same way. |
| 9 | It lasts about 5 years, with about 45,000 cubic metres piling up updrift. | The downdrift deficit is 12,000 minus 9,000, or 3,000 cubic metres a year, so 15,000 divided by 3,000 gives 5 years, while 9,000 times 5 is 45,000 cubic metres trapped updrift. |
| 10 | It is an erosional feature: widening by 12 m means the cliff foot has retreated 12 m, so erosion has increased. | The platform grew from 8 m to 20 m, a gain of 12 m, but a wave-cut platform is cut by cliff retreat and abrasion, so its width is rock removed, not sand added; depositional forms are spits, bars and beaches, which look and sit differently. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
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