| Date | November 2018 | Marks available | 1 | Reference code | 18N.2.SL.TZ0.1 |
| Level | Standard Level | Paper | Paper 2 | Time zone | Time zone 0 |
| Command term | Describe | Question number | 1 | Adapted from | N/A |
Question
Figures 1(a) and 1(b) show the availability of renewable freshwater per capita in 2013 and its predicted availability in 2040.
Figure 1(a): Water stress by country in 2013
Figure 1(b): Predicted water stress by country in 2040
[Source: Maps adapted from www.wri.org. File licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)]
Figure 2: Relationship between vegetation cover and evaporation
from different soil types
© International Baccalaureate Organization 2018
Using Figures 1(a) and 1(b):
State one country with no expected change in water stress between 2013 and the 2040 prediction.
State one difference in water scarcity between 2013 and the 2040 prediction.
Outline how climate change may affect the availability of freshwater resources.
Describe two water management strategies that can reduce water scarcity.
Describe the overall trend for sandy soil shown in Figure 2.
Calculate the change in evaporation from clay soil when the vegetation cover changes from 50% to 100%.
Outline two reasons why loam soils are the most productive for plant growth.
Markscheme
Canada/Argentina/Russia/Saudi Arabia/Australia/Mexico/Brazil/India/UK.
Note: Do not credit names from Fig1(a), e.g. Europe/Australasia, as these are not country names. Credit may be given for valid countries not labelled in Fig 1(b) e.g. Peru/Libya/Sri Lanka.
increased water scarcity in eg USA/France/Namibia/Spain/China;
increased water scarcity in some countries in sub-Saharan/southern countries in Africa/Middle East;
decreased water scarcity in eg Venezuela/Japan.
Note: a single named country OR a named region AND the difference (increase/decrease) is required for [1] mark. Credit reference to countries not named in Fig1(b), as long as difference is clearly identified.
increased temperatures/evaporation may lead to increased loss of soil water/aridity/desertification;
increased temperatures/evaporation may cause loss/salination of water supplies lakes etc;
changes in precipitation/increased frequency of El Nino events may lead to increase/decrease of water supply/droughts;
rising sea levels may lead to inundation/salination of ground water;
increased temperatures may cause melting of glaciers/ice caps leading to increase/decrease of water availability (i.e. by increased input to lakes/run-off to oceans).
Note: to gain credit, each statement should clearly identify the "climate change" element (e.g. increased temperature / decreased precipitation / sea level rise / increased monsoons/typhoons/hurricanes / higher frequency of El Nino / increased evaporation), AND its effect to freshwater resources (e.g. increased supply by melting ice sheets of mountaintops / reduced stream discharge / reduced amount of water in lakes / increased soil aridity / increased salinity / increased or decreased groundwater supply).
desalinisation to increase available supply;
use of water-saving agricultural strategies eg drip irrigation/terracing;
aqueducts/pipelines to move water from water-rich to water-scarce areas;
education/campaigns/increased charges so citizens use less water;
reduce production of crops with high water demand e.g. meat/dairy/almonds/cotton;
use of technology to collect/recycle/reuse water e.g. dams/rainwater/grey-water;
clean-up/restoration of polluted freshwater bodies/lakes/aquifers.
Note: Alternative valid responses may be credited but to gain credit they must identify appropriate strategy and at least indicate its relevance in addressing water scarcity as in MPs above.
Only credit valid “management” strategies as opposed to personal behaviour choices eg taking short showers/turning taps off.
as amount/% of vegetation increases the amount of evaporation from soil declines / negative correlation between evaporation and vegetation cover.
20 − 5 = 15; Allow 14−16
Note: Response needs to show calculation to gain credit.
because it is a good balance of sand and clay avoiding each of their more negative qualities;
not prone to waterlogging / has good drainage (compared to clay);
allows easy root penetration / workability (compared to clay);
allows good aeration / oxygen supply to roots (compared to clay);
stable / not prone to wind erosion (compared to sand);
retains moisture (compared to sand);
retains nutrients/minerals (compared to sand).
Examiners report
Vast majority of candidates could identify a country with no expected change.
Candidates generally identified a specific change in a given country or region but some made statements that were too broad for validity e.g. “water scarcity will increase”.
Most candidates could identify one impact of climate change on water availability, although, again, a number made statements that were too vague for credit.
Many were able to describe appropriate strategies, but it was quite common for candidates to offer glib responses like ‘turn taps off after use’ or ‘take shorter showers’ that could not be credited as “management strategies”.
Most candidates could clearly identify the trend shown.
Only a minority of candidates failed to complete this calculation correctly but, given its simplicity, the minority was quite sizable. Some lost credit for not showing their working which is required by this command term.
Candidates grasp of the nature of loam soils proved generally strong in addressing this question.
