| Date | May 2018 | Marks available | 6 | Reference code | 18M.2.bp.2 |
| Level | SL and HL | Paper | 2 | Time zone | |
| Command term | Explain | Question number | 2 | Adapted from | N/A |
Question
The diagram shows some possible water movements in the hydrological cycle.
[Source: © International Baccalaureate Organization 2018]
State the four elements of the hydrological cycle labelled A–D.
State two possible methods of artificially recharging the aquifer.
Explain three possible ways people may modify a river channel to increase the flow of water.
To what extent has the management of one major wetland area been successful?
Markscheme
Award [2] for all four correct answers, [1] for two or three correct answers.
A = evaporation
B = precipitation (accept rainfall)
C = infiltration (accept percolation)
D = groundwater flow (accept baseflow).
Award [1] for any of the following points, up to a maximum of [2]:
- the creation of recharge basin lakes
- controlled flooding/irrigation
- water pumped down the bore hole
- drainage diversion
- other valid methods.
In each case, award [1] for correct identification of a method and [1] for a valid explanation of how it increases the flow of water (may make applied use of concepts such as wetted perimeter, hydraulic radius, channel efficiency).
For example, straightening/shortening a river channel [1] increases the gradient and therefore the velocity [1].
Other possibilities include:
- concreting the channel/decreasing the roughness
- widening/deepening/levees
- dredging.
Responses should clearly identify one major wetland. If more than one wetland is referred to, credit only the first.
Major wetlands include, for example, the Kissimmee, the Everglades, Norfolk Broads.
Responses should clearly outline the management with respect to why it was needed and its aims. There are numerous reasons why wetlands are managed: biodiversity issues, restoration of wetlands, ecotourism, natural flood defenses. Management can then be evaluated in terms of how successful it has been (or not).
Good answers may discuss the extent to which different stakeholders have different perspectives on whether the strategy has been successful. Another approach might be to evaluate the extent to which all aims and objectives have been met (there may be spatial and temporal dimensions to this).
At band D, responses should describe the management of a major named wetland, and may assert partial success/failure.
At band E, there should be either greater explanation of the strengths and weaknesses of the management, or a critical evaluation of the extent of success.
At band F, expect both.
Marks should be allocated according to the Paper 2 HL and SL markbands.
