Date | May 2018 | Marks available | 1 | Reference code | 18M.2.bp.3 |
Level | SL and HL | Paper | 2 | Time zone | |
Command term | Estimate | Question number | 3 | Adapted from | N/A |
Question
The diagram shows wind frequency over a 30-year period on a beach in the Caribbean.
[Source: © International Baccalaureate Organization 2018]
Estimate the percentage of days when the wind blows from the north.
Identify the direction of the most frequent wind.
State the direction towards which longshore drift is most likely to occur at X on the diagram.
State one landform likely to be produced by longshore drift at X.
Explain three physical factors that affect the development of coral reefs.
“Coastal hazard management always creates more problems than it solves.” Discuss this statement, with reference to one or more areas of coastline.
Markscheme
15 % (accept 13–17 %).
ESE (accept SE).
West/north west/west northwest.
Spit.
Award [1] for each factor explaining the development (growth or decline) of coral and [1] for its development and/or exemplification.
For example:
- Presence of polyps/zooxanthellae (soft animals) [1] which produce calcium carbonate to form the reefs [1].
- Sunlight for photosynthesis [1]; coral growth favoured in tropical oceans where sunlight is more intense [1].
Other factors include:
- clear, shallow water
- optimal sea temperatures of 23–29°C
- acidity of water
- salinity of water
- where water is less saline
- natural hazards can destroy reef
- natural predators
- climate change.
The question can be answered using any coastal hazard, including tsunamis, storm surges, coastal erosion and cliff failure. Answers should include a discussion of the conflicts involved with coastal hazard management. These may include access, decline of amenity value, cost, disruption of ecosystems, impact on fisheries, impact on transport or lack of management.
For example, sea walls may be built to reduce the threat of tsunamis and storm surges but may interfere with natural ecosystems and shipping routes. Erosion may be managed using hard and soft engineering, but this may affect the aesthetics of an area and reduce its recreational/tourist impact. A “do nothing”/managed retreat may anger local residents land owners.
In contrast, many people feel more secure as a result of attempts to manage coastal hazards, and do not see a conflict of interest.
Good candidates may discuss different coastal hazards and stakeholders and cover both sides of the argument. Another approach may be to examine the scale of the hazard, eg a 50-year event may be planned for, but the scheme will not protect against an event of higher magnitude. Others may consider the possible impacts of climate change.
At band D, expect a description of the hazard management of one or more areas of coastline.
At band E, expect either a detailed explanation of the hazard management of one or more areas of coastline or a discussion of the problems created and resolved by hazard management.
At band F, expect both.
Marks should be allocated according to the Paper 2 HL and SL markbands.