36 exam-style questions on Water access, use and security — topic 4.2 of Water in the IB Environmental Systems and Societies syllabus — with answers and explanations. Samples below; the full set is free with an account.
Which sector accounts for the largest share of global freshwater withdrawal?
Answer: agriculture, mainly for irrigation
Irrigation takes roughly 70 % of withdrawals worldwide, which is why demand-side measures in farming release far more water than household savings can. Hydroelectricity is a non-consumptive use, not a withdrawal.
A coastal city replaces groundwater abstraction with a large reverse osmosis plant. The most likely environmental cost of this switch is
Answer: discharge of hypersaline brine to the sea
Desalination separates fresh water from a saline input, so the output is a concentrated brine that is denser than seawater and sinks onto benthic communities near the outfall; the plant's high energy demand is the second major cost.
A large storage dam is completed on the upper reach of a river that flows on through two further countries. The most likely source of dispute between the states is that
Answer: downstream states lose control of the timing and volume of flow
A dam converts a shared flow into a storage controlled by one state, so downstream users depend on decisions taken elsewhere about when and how much to release. Shared basins are managed by treaty for exactly this reason, and the hard part of any such treaty is agreeing a rule for dry years rather than for average ones.
Groundwater beneath a coastal city is pumped for several decades at a rate well above natural recharge. Which pair of consequences is most likely?
Answer: The land surface subsides and seawater intrudes into the aquifer
Removing water reduces the pressure supporting the sediment, so the ground settles, and lowering the freshwater level lets denser saltwater move inland beneath it. Subsidence is largely irreversible, and once an aquifer is salinised it can take generations to flush, so both effects outlast the pumping that caused them.
A dispersed rural settlement in a monsoon region has no piped supply and no capital for a treatment works, but receives about 1 100 mm of rain in four months of the year. The most appropriate supply strategy is
Answer: roof rainwater harvesting into household storage tanks
The constraint here is storage and capital rather than total rainfall, so the appropriate technology is small, cheap and installed household by household. Desalination and transfer schemes solve a shortage of water; this settlement has a shortage of infrastructure.
In many low-income urban districts water is physically available but not safe to drink. The largest health consequence of this is
Answer: diarrhoeal disease from faecally contaminated drinking water
Water contaminated with faeces spreads cholera, typhoid and other diarrhoeal diseases, which cause far more illness and death than any other water-related hazard, falling heaviest on children under five. Dissolved metals such as arsenic are serious but local, and dehydration does not fit because the water is available: the problem is quality, not quantity.
That was 6 of 36 Water access, use and security questions.
Practise all 36 freeOutlineAO2 · 1–4 marks
A brief account or summary: the main points in two or three sentences, no evaluation.
DistinguishAO2 · 1–4 marks
Make the difference clear for BOTH terms — a definition of one of them is only half an answer.
36 Water access, use and security questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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