| Date | May 2017 | Marks available | 2 | Reference code | 17M.2.SL.TZ0.2 |
| Level | Standard Level | Paper | Paper 2 | Time zone | Time zone 0 |
| Command term | Identify | Question number | 2 | Adapted from | N/A |
Question
Water stress is the total annual extraction of water as a proportion of the renewable supply in a given area. If the extraction represents 40 % or more of the available supply it is described as a high risk area.
Figure 2: Water stress for selected crops
[Source: World Resources Institute,
http://www.wri.org/resources/charts-graphs/portion-agricultural-production-under-high-or-extremely-high-stress.
Used with permission.]
State the crop that is under the greatest water stress.
Identify two strategies that could be used to grow crops in areas of high water stress.
Identify three factors that may lead to an increase in water stress.
Markscheme
cotton
improved irrigation efficiency eg drip irrigation;
use crop cultivars that require less water (eg drought resistant seeds/GMOs) / replace high stress crops (eg cotton) with low stress (eg oats);
improve water catchment/storage with dams; reservoirs;
install desalinization plants in coastal areas;
plant cover crops/use terracing (to reduce evaporation/run-off losses);
use salt-tolerant crops to exploit available sea-water/saline soils.
Do not credit simply “irrigation”. Too vague.
increased demand through increased population / domestic/agricultural/industrial use;
increased water consumption through more affluent lifestyles / shift to meat-rich diets;
move towards more intensive agriculture/irrigation / unsustainable abstraction of water;
movement of water out of drainage basin eg aqueducts / upstream use by other countries;
growing of inappropriate/heavily water-dependent crops;
deforestation in drainage basin / pollution/contamination of water sources;
drought/reduction of rainfall (due to global warming/El Niño).
Award [1] for each correct factor identified, up to [3 max].
For last MP, do not accept simply a description of a regular climate eg low rainfall/dry season. The question asks for what will increase stress, so there needs to be a suggestion of change.
Marking points above may be stated as given or explicitly demonstrated through reference to examples/case studies (eg cotton around Aral Sea absorbs excessive water from an environment at risk).
Examiners report
The vast majority correctly associated cotton with highest water stress.
Majority of candidates could identify at least one appropriate strategy …incorrect responses were generally due to being too vague or inaccurate e.g. ‘better irrigation’; ‘crop rotation’.
Most candidates could come up with a couple of valid causes of water stress …incorrect answers again were often too vague e.g. ‘growing lots of crops’ and a significant number mistook water stress for flooding.
