IB ESS SL 4.2.8 Water Scarcity Mitigation Strategies Questions
Compare integrated strategies for mitigating water scarcity.
- Syllabus
- First assessment 2026
- Course
- ESS SL
- Level
- SL
Exam points
- identify water-scarcity mitigation strategies including demand reduction, efficient irrigation, rainwater harvesting, grey-water reuse, reservoirs, diversion, desalination, pollution control and wetland restoration
- explain how behaviour change, technology and integrated management alter freshwater supply, demand, quality and environmental flows
- evaluate mitigation strategies by comparing sustainability, cost, energy use, environmental impacts, equity, stakeholder acceptance and resilience to drought
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IB ESS SL 4.2.8 Water Scarcity Mitigation Strategies Questions question 1
[Maximum number: 7]
Evaluate the sustainability of two water management strategies to improve access to freshwater resources in a society.
Examples of strategies [2 max]:
i. reservoirs;
dams;
rainwater harvesting;
water diversion projects;
international sale of water resources;
desalination;
artificial glaciers;
cloud seeding;
water conservation/grey water reuse;
restoration of wetlands;
prevention of water pollution;
pumping of aquifers;
Evaluation may include factors such as...
ii. impact of cost on economic sustainability of population;
iii. demand placed on human / physical resources;
iv. climate impact - carbon negative/neutral/positive;
v. impact on ecosystem resilience;
vi. impact on biodiversity;
vii. interference with natural cycles;
viii. limiting geographical/climatic factors;
The following examples of water management strategies and their evaluation show how credit can be given for any appropriate strategy.
Example 1: Rainwater harvesting;
Positive:
does not impact natural water cycle / replenishment rate / impossible to reduce natural income;
free natural capital;
useful for watering plants/irrigation / washing / fire protection / (thus) reduces consumption of groundwater/other freshwater resources;
Negative:
availability restricted temporally and spatially (unequal distribution of rain / unpredictable supply);
usually not safe for drinking;
can't satisfy needs of irrigation of commercial agriculture;
Example 2: Desalinization;
Positive:
sustainable if energy required produced by photovoltaic cells;
sea water is more available than freshwater;
provides accessible/safe drinking/irrigation water;
salt may be used for producing useful chemical products (sodium hydroxide, hydrochloric acid);
reduces pressure on freshwater reserves that need protection;
Negative:
requires huge amounts of energy / increase GCC if fossil fuel used;
not available in landlocked countries;
building of facilities result in environmental damage/pollution;
disposing of salt (brine) poses environmental hazards/pollutes ocean / salt is contaminated so can't be eaten;
high cost to build and operate that may be economically unsustainable;
Notes: Award [1 mark] for each appropriately identified strategy for improving access to freshwater up to [2 max].
Do not accept simplistic statements not clearly linked to sustainability, eg. cheap / efficient / doesn't need elaborate equipment/scientific expertise.
Accept statements such as "its cost is too great to be economically sustainable / its cost may divert economic resources away from habitat/species protection / resource requirement maybe unsustainable for LEDCs".
Award [5 max] if only positive OR only negative evaluation OR only one strategy evaluated.
Award [1 max] for each clear negative or positive evaluation of each factor.
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