Question 1
A settlement has a freshwater supply, but contamination sometimes makes the water unsafe to drink and seasonal interruptions leave households without water for several days.
Define water security.
[2]
State one reason why the settlement does not have water security.
[1]
Question 2
Figure 2 shows the daily water use of a household before and after a water-conservation programme.
Daily household water use before and after a water-conservation programme, with measures applied.
| Use category | Before / | After / | Conservation measure |
|---|---|---|---|
| Toilets | 120 | 60 | Low-flush toilets; treated laundry grey water for flushing |
| Showers | 140 | 105 | Shower-flow regulators |
| Laundry | 70 | 50 | No specific measure shown |
| Kitchen | 45 | 40 | No specific measure shown |
| Outdoor use | 125 | 45 | Rainwater tank supplies garden |
| Total | 500 | 300 | Total daily use |
Identify the category with the greatest absolute reduction in daily water use.
[1]
Calculate the percentage reduction in total daily household water use.
[2]
Explain how two measures shown in Figure 2 reduce demand for treated mains water.
[3]
Question 3
Figure 1 shows freshwater availability and household access in three districts of the fictional country of Maliba.
Freshwater availability, safely managed piped-water access and access context in three districts of Maliba.
| District | Freshwater availability / | Households with safely managed piped water / % | Water infrastructure | Access context |
|---|---|---|---|---|
| Central City | 920 | 98 | Extensive public treatment and pipe networks | Not specified |
| Floodplain Villages | 2400 | 44 | Seasonal river; no treatment plant or distribution network | Connection fee = one month’s median income; may create an affordability barrier; women and girls make 76% of water-collection journeys |
| Arid Town | 620 | 79 | Subsidized water transferred through a government pipeline | Not specified |
Identify the district with the greatest freshwater availability and the district with the greatest household access to safely managed piped water.
[2]
Calculate the difference, in percentage points, between household access in Central City and Floodplain Villages.
[2]
Explain how the data illustrate that freshwater availability does not necessarily produce equitable access.
[3]
Question 4
Figure 1 summarizes water access in the rapidly growing town of Darsana.
Identify one economic factor limiting equitable access to water in Darsana.
[1]
Outline one social impact of the pattern of water access shown in Figure 1.
[1]
Outline one political factor contributing to unequal access and one measure that could address it.
[2]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 5
The population of a city is projected to increase from 240 000 to 270 000. Average domestic water use is expected to remain at .
Calculate the projected total domestic water demand, in litres per day. Show your working.
[2]
Outline one reason why economic development may increase domestic water use per person.
[1]
Outline one way urban growth may reduce groundwater recharge.
[1]
Question 6
Figure 2 shows a reverse-osmosis desalination system.
Explain the role of the semi-permeable membrane in producing freshwater.
[2]
State one environmental disadvantage of desalination.
[1]
State one way enhancing natural wetlands may increase usable water supplies.
[1]
Question 7
Two communities experience limited access to water. Community A is in an arid basin where withdrawals exceed the small renewable supply. Community B is beside a seasonally abundant river but lacks treatment, storage and distribution infrastructure.
Distinguish between the types of water scarcity experienced by communities A and B.
[2]
Outline how domestic water metering may reduce demand and identify one equity concern associated with it.
[2]
Question 8
The fictional Makira basin contains a humid upland area and a semi-arid eastern plain. Most urban growth is occurring in informal settlements on the eastern edge of Makira City.
Makira City household water access, use, price and management context.
| Indicator / fact | High-income central | Mixed-income outer | Low-income informal |
|---|---|---|---|
| Piped-water access / % | 98 | 74 | 22 |
| Mean water use / | 165 | 105 | 42 |
| Mean price / currency units | 0.8 | 1.4 | 5.6 |
| Unconnected-household supply | — | — | Tanker vendors serve unconnected households |
| Farm water allocation | Commercial farms hold long-term abstraction permits | — | — |
| Treatment capacity | Treatment plant operates at full capacity | — | — |
| Proposed measures | Network extensions; lifeline tariff; permit reviews | — | — |
Calculate how many times greater the mean price of water is in the low-income informal district than in the high-income central district.
[2]
Distinguish between the physical and economic causes of water scarcity in the Makira basin.
[2]
Explain how economic and political factors contribute to unequal access to water in Makira City.
[3]
Evaluate the proposed measures for improving equitable water security in the Makira basin.
[4]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 9
During a two-year drought, the municipality of Arroyo Verde introduced household metering, an increasing-block tariff and rebates for low-flush toilets. A minimum allocation of 50 litres per person per day was charged at the lowest tariff.
Identify the income group with the greatest absolute reduction in mean water use.
[1]
Using the mean values of 142 litres per person per day before the measures and 104 litres per person per day after one year, calculate the percentage decrease in mean water use by middle-income households.
[2]
Explain how two of the measures reduced domestic water use.
[3]
Evaluate the effectiveness and equity of Arroyo Verde's domestic water-conservation programme.
[4]
Question 10
Table 1 compares four proposed methods of increasing the water supply of a coastal region. The region experiences frequent droughts and contains an important estuary.
Comparison of projected water-supply options for a coastal region; supply and drought-output figures are projected annual averages.
| Water-supply option | Additional supply / | Electricity use / | Capital cost / million local currency units | Output retained in severe drought / % | Principal environmental effect |
|---|---|---|---|---|---|
| Reservoir | 28 | 0.08 | 95 | 45 | of habitat inundated |
| Roof rainwater catchment | 6 | 0.03 | 18 | 35 | Little land disturbance |
| Reverse-osmosis desalination | 18 | 3.6 | 140 | 100 | Concentrated brine discharged near the estuary |
| Wetland enhancement | 9 | 0.05 | 32 | 70 | of wetland habitat restored |
Identify the option with the greatest additional annual supply and the option that retains the greatest percentage of its output during severe drought.
[2]
Calculate the annual electricity use of the desalination plant, in GWh, if it produces its projected annual supply.
[2]
Suggest a suitable two-option portfolio for the region, using evidence from Table 1.
[3]
Question 11
Figure 3 compares three food-production systems used to produce leafy vegetables in a dry region.
Annual inputs, yield and capital cost for three leafy-vegetable production systems in a dry region.
| Measure | Flood irrigation | Drip irrigation | Recirculating aquaponics |
|---|---|---|---|
| Water input / | 9000 | 5400 | 2200 |
| Vegetable yield / | 6.0 | 6.6 | 8.8 |
| Electricity use / | 0.3 | 0.8 | 7.5 |
| Capital cost | Low | Medium | High |
| Water circulation | — | — | Fish tanks microbial filters plant beds fish tanks; losses mainly through evapotranspiration |
Calculate the water productivity of drip irrigation in kilograms of vegetables per cubic metre of water.
[2]
Compare flood irrigation with drip irrigation using the data in Figure 3.
[2]
Suggest whether aquaponics is the most suitable system for increasing food production in this region.
[3]
Question 12
Malta has limited natural freshwater. Its water strategy includes desalination, treatment and reuse of wastewater, repair of leaking pipes and water-efficient food production.
Explain how aquaponics can reduce water consumption in food production.
[2]
Outline how two of Malta's strategies can improve water security.
[2]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 13
Freshwater governance operates at different scales, from restrictions imposed on individual users during droughts to agreements governing rivers shared by countries.
Outline one local regulation that could reduce urban water use during a severe drought and how it would reduce demand.
[2]
Explain why international agreements may be necessary for a transboundary river.
[2]
Question 14
Figure 4 shows the design of a citizen-science programme for monitoring streams.
Identify two features shown in Figure 4 that improve the reliability of the combined data.
[2]
Outline one benefit and one limitation of citizen science for local water management.
[2]
Question 15
Port Selene is a rapidly growing coastal city with variable rainfall. The city authority is considering several ways to meet future water demand.
Port Selene water-supply capacity and supporting system data for 2025 and the proposed 2040 system.
| Indicator | 2025 | Proposed 2040 | Quantity / unit |
|---|---|---|---|
| Reservoir supply | 72 | 70 | |
| Planned groundwater supply | 34 | 25 | |
| Rainwater catchment | 8 | 15 | |
| Water reuse | 6 | 30 | |
| Desalination supply | 0 | 40 | |
| Total reliable capacity | 120 | 180 | |
| Projected water demand | — | 175 | |
| Population | 1.20 | 1.65 | million people |
| Reservoir evaporation | — | 9 | |
| Electricity from fossil fuels | — | share of electricity | |
| Electricity from renewables | — | share of electricity |
Calculate the percentage increase in reliable water-supply capacity between 2025 and the proposed system in 2040.
[2]
Explain why water demand in Port Selene is projected to increase.
[2]
Analyse two environmental consequences of the proposed change in the city's water-supply system.
[3]
Evaluate whether reverse-osmosis desalination is an appropriate strategy for improving Port Selene's water security.
[4]
Question 16
The semi-arid country of San Aurelio is selecting food-production strategies for a national water-scarcity programme. Three pilot systems produced tomatoes on equal land areas.
Resource inputs and tomato yields for three pilot production systems.
| Production system | Water input / m ha yr | Electricity / MWh ha yr | Tomato yield / t ha yr |
|---|---|---|---|
| Flood-irrigated field | 9000 | 0.4 | 45 |
| Drip-irrigated field | 5200 | 1.0 | 58 |
| Recirculating greenhouse with harvested rainwater | 2600 | 12.0 | 96 |
Identify the system with the highest tomato yield.
[1]
Calculate the water productivity of the drip-irrigated field in kilograms of tomatoes per cubic metre of water.
[2]
Explain how aquaponics conserves water while producing food.
[3]
Evaluate the proposed strategies for reducing water scarcity in San Aurelio's food-production system.
[4]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 17
Figure 4 presents monthly river-flow indicators and separate basin-wide annual indicators for the fictional Luma River basin. The annual basin indicators include all renewable water sources and all consumptive uses in the basin, not only the river-flow series shown.
Monthly river-flow indicators and separate basin-wide indicators for the Luma River basin. Annual basin totals include all renewable sources and consumptive uses, not only the monthly river-flow series.
| Month or basin-wide indicator | Natural river flow / | Consumptive withdrawals / | Remaining river flow / | Minimum environmental flow / | Basin-wide indicators (separate scope) |
|---|---|---|---|---|---|
| January | 240 | 70 | 170 | 60 | — |
| February | 220 | 65 | 155 | 60 | — |
| March | 180 | 60 | 120 | 60 | — |
| April | 140 | 55 | 85 | 60 | — |
| May | 110 | 50 | 60 | 60 | — |
| June | 90 | 45 | 45 | 60 | — |
| July | 85 | 40 | 45 | 60 | — |
| August | 95 | 42 | 53 | 60 | — |
| September | 125 | 50 | 75 | 60 | — |
| October | 165 | 58 | 107 | 60 | — |
| November | 210 | 65 | 145 | 60 | — |
| December | 235 | 70 | 165 | 60 | — |
| Annual basin-wide water balance (all sources and uses; not only monthly river series) | — | — | — | — | Total renewable basin supply: 2.40 per year; total consumptive use: 1.56 per year |
| Groundwater level change | — | — | — | — | Most recent decade: -1.8 m |
| Root-zone soil-moisture index | — | — | — | — | Most recent decade: 100 to 76 |
Calculate consumptive use as a percentage of total renewable basin supply.
[2]
Identify the months in which remaining river flow is below the minimum environmental flow.
[1]
Explain how the indicators suggest increasing risk of transgressing the freshwater planetary boundary.
[3]
Question 18
Figure 5 shows a transboundary river basin before and after the four riparian states adopted a water-governance agreement.
Calculate the percentage increase in downstream dry-season flow following the agreement.
[2]
Outline two provisions of the agreement that could improve sustainable freshwater management.
[2]
Explain why the agreement may not distribute the benefits of the river equitably among the four states.
[3]
Question 19
Figure 6 compares the water footprints of five products. Green water is precipitation stored in soil, blue water is withdrawn surface water or groundwater, and grey water is the volume required to dilute pollutants.
Supply-chain average water footprints; high-stress values refer to blue water.
| Product | Green water / | Blue water / | Grey water / | Total / | Blue water from high-stress basins / % |
|---|---|---|---|---|---|
| Lentils | 500 | 200 | 100 | 800 | 10 |
| Rice | 1200 | 900 | 300 | 2400 | 65 |
| Beef | 7000 | 6500 | 1500 | 15000 | 45 |
| Cotton textile | 3000 | 6000 | 1000 | 10000 | 80 |
| Steel | 20 | 180 | 60 | 260 | 70 |
Calculate how many times greater the total water footprint of beef is than that of lentils.
[2]
Describe two patterns shown by the data.
[2]
Evaluate the usefulness of these water-footprint data for a company deciding which materials or foods to purchase.
[3]
Question 20
Freshwater use is monitored as a planetary boundary because excessive human pressure can cause abrupt or irreversible changes to hydrological systems.
Outline two reasons why a single global annual withdrawal total is insufficient for measuring this planetary boundary.
[2]
State one hydrological variable, other than human withdrawals, that could be monitored.
[1]
Outline one strategy for reducing the risk of transgressing the freshwater planetary boundary.
[1]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 21
Figure 3 shows average water footprints for selected products. Values include direct and indirect water used during production.
Calculate the water footprint of producing of lentils. Show your working.
[2]
Outline two limitations of using the values in Figure 3 alone to make decisions about sustainable consumption.
[2]
Question 22
A country has an annual clean and accessible water supply of and a population of . Water stress is defined as a clean, accessible supply below per person per year.
Calculate the annual clean and accessible water supply per person. Show your working.
[2]
State whether the country is experiencing water stress according to the threshold.
[1]
State one reason why the threshold may not fully represent water stress within the country.
[1]
Question 23
Figure 5 presents two contrasting socio-economic contexts of increasing water stress.
Outline how the principal cause of increasing water stress differs between the two countries.
[2]
Suggest one management response appropriate to each country.
[2]
Question 24
The fictional Lydra basin supplies cities, irrigated agriculture and internationally important wetlands. Monitoring has indicated increasing pressure on the basin's hydrological system.
Lydra basin hydrological indicators, 2000–2025. Water-stress threshold: ; recommended minimum dry-season flow: of natural flow.
| Year | Clean accessible supply / | Groundwater depth below ground / | Dry-season flow / of natural flow |
|---|---|---|---|
| 2000 | 2400 | 18 | 82 |
| 2005 | 2150 | 20 | 76 |
| 2010 | 1900 | 24 | 68 |
| 2015 | 1650 | 31 | 57 |
| 2020 | 1420 | 39 | 44 |
| 2025 | 1280 | 47 | 36 |
State the first year in which the Lydra basin fell below the water-stress threshold.
[1]
Calculate the percentage decrease in dry-season river flow from 2000 to 2025, relative to the 2000 flow value.
[2]
Analyse why the basin was experiencing water stress by 2025 rather than only water scarcity.
[3]
Evaluate the evidence for determining whether freshwater use in the Lydra basin is approaching or crossing a planetary boundary.
[4]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 25
The River Oranta flows through the upstream state of Bellona, the mid-basin state of Caris and the downstream state of Daran before reaching a delta wetland. The states are negotiating a basin agreement.
Oranta basin water use and proposed agreement provisions.
| Basin component or agreement item | Value | Details |
|---|---|---|
| Mean annual renewable river flow | Whole-basin mean annual flow rate | |
| Bellona | Current consumptive use; upstream hydropower reservoir releases | |
| Caris | Current consumptive use; irrigation abstraction and saline agricultural return flows | |
| Daran | Current downstream consumptive use | |
| Delta wetland | Proposed minimum annual environmental flow | |
| Abstraction monitoring | Current abstraction points metered | |
| Release information | Monthly | Reservoir release data shared under the agreement |
| Drought rule | Storage below | Joint drought trigger; each state's allocation reduced by |
| Water quality | Common standard | Salinity standards apply across the basin |
| Dispute resolution | Independent panel | Panel established under the agreement |
| Decision-making | Proportional voting | Voting power is proportional to financial contribution |
Identify one activity in an upstream state that may reduce water security in Daran.
[1]
Calculate the volume and percentage of mean annual renewable flow remaining after current consumptive use.
[2]
Explain why both national regulation and international cooperation are required to manage the Oranta basin sustainably.
[3]
Evaluate the proposed agreement as a means of maintaining sustainable and equitable freshwater use in the Oranta basin.
[4]
Question 26
The government of Norvale is reviewing the water footprint of household consumption and its dependence on imported products.
Average water footprints of selected products, divided into blue, green and grey water components.
| Product | Blue water / | Green water / | Grey water / | Total / |
|---|---|---|---|---|
| Beef | 800 | 14 000 | 200 | 15 000 |
| Cheese | 350 | 4 500 | 150 | 5 000 |
| Rice | 1 600 | 700 | 200 | 2 500 |
| Cotton | 4 000 | 4 500 | 500 | 9 000 |
| Steel | 180 | 0 | 50 | 230 |
| Tomatoes | 120 | 80 | 20 | 220 |
Calculate the annual water footprint associated with Norvale's imported beef, in cubic metres.
[2]
Distinguish between direct and indirect components of a household water footprint.
[2]
Analyse why the size of a product's water footprint alone is insufficient for judging its sustainability.
[3]
Evaluate the use of water-footprint evidence to guide Norvale's trade and consumption policies.
[4]
Question 27
A community-science programme monitored turbidity in the Alder Stream after rainfall. Volunteers used identical handheld meters, uploaded geotagged results to an open database and collected duplicate samples for professional laboratory analysis at selected sites.
Identify the validation site with the greatest difference between volunteer and professional turbidity measurements.
[1]
Calculate the percentage by which the volunteer measurement at site G exceeded the professional measurement.
[2]
Analyse the reliability and representativeness of the community-science data.
[3]
Evaluate the role of citizen science in managing water stress in the Alder Stream catchment.
[4]
Question 28
A citizen-science programme monitored water security in the rapidly industrializing fictional Nera district. Figure 7 presents regional water data and paired turbidity measurements made by volunteers and professional scientists. The six paired sites shown are selected examples from the wider programme; the 70% road-proximity statistic and the 10% professional-validation statistic refer to all programme sampling sites.
Calculate the clean accessible freshwater supply per person per year and determine whether the district falls below the water-stress threshold.
[2]
Explain why the district may experience water stress even though its total renewable freshwater supply exceeds the threshold.
[2]
Evaluate the reliability and usefulness of the citizen-science programme for managing the district's water resources.
[4]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 29
Outline how water security contributes to the sustainability of a society.
[4]
Explain how social, cultural, economic and political factors can interact to produce inequitable access to freshwater.
[7]
Using named examples, evaluate strategies for achieving equitable water security.
[9]
Question 30
Explain why population growth and economic development may increase water demand.
[4]
Explain how different supply-side strategies may increase freshwater availability and affect natural systems.
[7]
Using named examples, evaluate whether engineered supply projects are the most appropriate way to improve water security.
[9]
Question 31
Outline four domestic techniques that conserve freshwater.
[4]
Explain how water-conservation strategies can reduce water use in food-production systems.
[7]
Using named examples, to what extent can water conservation provide greater water security than increasing water supplies?
[9]
Question 32
Distinguish between water scarcity and water stress.
[4]
Explain how evidence can be used to assess whether freshwater use is approaching a planetary boundary.
[7]
Using named examples, to what extent can basin-level management prevent transgression of the freshwater planetary boundary?
[9]
Build a Practice Exam — ESS HL
Test your knowledge with a custom paper containing questions from selected topics.
Question 33
Outline four features of effective freshwater governance.
[4]
Explain why both local regulation and international cooperation may be required to manage freshwater sustainably.
[7]
Using named examples, evaluate the effectiveness of multilevel governance in maintaining freshwater use at sustainable and equitable levels.
[9]
Question 34
Explain how water footprints can inform decisions about sustainable water use.
[4]
Explain how citizen science can provide useful and reliable evidence for local water-resource management.
[7]
Using named examples and contrasting socio-economic contexts, evaluate the usefulness of information-based approaches in reducing water stress.
[9]
The Ultimate All-in-One
IB Platform
All content on this website has been developed independently from and is not endorsed by the International Baccalaureate Organization. International Baccalaureate and IB are registered trademarks owned by the International Baccalaureate Organization.