WaterIB Environmental Systems and Societies HL: Topic test

20 questions, 54 marks

IB Environmental Systems and Societies HL

Water topic test

Total 54 marks

Name

Class

Date

1
A town in England was built on the floodplain of a river. Over fifty years, forest on the hills upstream was cleared for grazing, and new housing estates, roads and car parks were built across the fields beside the town. During recent heavy rain the river rose within hours and flooded streets that had flooded only rarely before.
(a)
Which flow in the hydrological cycle is most reduced by building roads and car parks?
[1 mark]
ASublimation
BCondensation
CAdvection
DInfiltration
(b)
Which two factors drive the movement of water through the hydrological cycle?
[1 mark]
ASolar radiation and gravity
BWind and tides
CThe Earth's magnetic field and gravity
DPlate tectonics and wind
(c)
Explain how clearing the forest upstream could increase the risk of flooding in the town.
[2 marks]
Total for question 1: 4 marks
2
Off the coast of Namibia, in the Benguela Current, winds blow surface water away from the shore. Cold water from deep in the ocean rises to replace it. This region is one of the most productive marine ecosystems in the world, supporting large fisheries for sardines, anchovies and hake. In many other parts of the open ocean, a warm surface layer sits above cold deep water and the two layers hardly mix.
(a)
What is meant by upwelling?
[1 mark]
AWarm surface water sinking to the sea floor
BA surface current flowing towards the poles
CCold, nutrient-rich water rising from depth to the surface
DA rise in sea level caused by melting ice
(b)
What is the thermocline in a stratified body of water?
[1 mark]
AA layer of ice at the surface
BA transition layer between the warm, mixed surface layer and the cooler deep water
CThe zone where river water meets sea water
DThe layer of the ocean with the greatest salinity
(c)
Explain why the Benguela region is much more productive than areas of stratified open ocean.
[2 marks]
Total for question 2: 4 marks
3
Singapore is a densely populated island with few natural lakes or rivers and no large aquifers. It meets its water needs through four national taps: rainwater collected from urban catchments and stored in reservoirs, water imported from Malaysia, reclaimed wastewater purified to a high standard (NEWater), and desalinated seawater. The government also charges for water at prices that reflect its scarcity and runs campaigns that encourage people to save water.
(a)
Outline three ways in which Singapore increases its water supply.
[3 marks]
(b)
Evaluate desalination as a strategy for addressing water scarcity.
[4 marks]
Total for question 3: 7 marks
4
The Grand Banks off Newfoundland, Canada, once supported one of the largest cod fisheries in the world, with catches of about 800 000 tonnes a year in the late 1960s as large factory trawlers arrived. Catches then fell steadily. In 1992 the Canadian government banned cod fishing, which put tens of thousands of people out of work. More than thirty years later, the cod stocks have recovered only partly.
(a)
Explain how the use of maximum sustainable yield (MSY) can help to prevent the collapse of a fishery.
[6 marks]
(b)
Discuss the risks of harvesting fish at the maximum sustainable yield (MSY) and the need for accurate stock assessment.
[6 marks]
Total for question 4: 12 marks
5
In August 2014 the city of Toledo, Ohio, USA, told about 400 000 residents not to drink or boil tap water for two days. The water was taken from Lake Erie, where a dense bloom of cyanobacteria (blue-green algae) had produced a toxin called microcystin. Runoff of phosphorus fertiliser and manure from farmland in the lake's catchment had enriched the lake for years.
(a)
Which nutrients most often cause eutrophication of freshwater lakes?
[1 mark]
AOxygen and carbon dioxide
BNitrates and phosphates
CSodium and chloride
DIron and copper
(b)
Why can an algal bloom be a threat to human health?
[1 mark]
AIt spreads disease from sewage to drinking water
BIt raises water temperature enough to boil
CIt removes all minerals from the water
DSome algae and cyanobacteria produce toxins that can poison people and animals
(c)
Outline two ways in which eutrophication of Lake Erie could be managed.
[2 marks]
Total for question 5: 4 marks
6
Between 2015 and 2017 the Western Cape region of South Africa had a severe drought. By early 2018 the dams supplying Cape Town were around a quarter full, and the city warned of "Day Zero", the day when most taps would be turned off. Residents were limited to 50 litres of water per person per day, farmers' allocations were cut, and many households installed rainwater tanks. Day Zero was avoided by large cuts in water use.
(a)
What is meant by water security?
[1 mark]
AOwning enough dams to supply a city
BHaving enough water for agriculture only
CHaving access to sufficient amounts of safe drinking water
DPreventing other countries from using a river
(b)
How is water stress defined?
[1 mark]
AA clean, accessible water supply of less than 1 700 cubic metres per person per year
BA clean, accessible water supply of less than 170 cubic metres per person per year
CA water supply of more than 1 700 cubic metres per person per year
DAny year with below-average rainfall
(c)
Suggest two techniques that households in Cape Town could use to conserve water.
[2 marks]
Total for question 6: 4 marks
7
The Indus river basin is shared by Pakistan, India, China and Afghanistan. In 1960 India and Pakistan signed the Indus Waters Treaty, brokered by the World Bank, to share the water of the river system. Most of Pakistan's agriculture depends on irrigation from the Indus system. Pakistan's population has grown rapidly, and the renewable water available per person has fallen to roughly 1 000 cubic metres per year. Glaciers that feed the rivers are shrinking, and groundwater is being pumped faster than it is recharged.
(a)
Distinguish between water scarcity and water stress, and state whether Pakistan is water stressed.
[3 marks]
(b)
Evaluate the role of local and global governance in keeping freshwater use at sustainable levels in the Indus basin.
[4 marks]
Total for question 7: 7 marks
8
Chile is one of the world's largest producers of farmed Atlantic salmon. The fish are raised in net pens in sheltered coastal waters and fed pellets made partly from wild-caught fish. They are treated with antibiotics to control disease. Escaped salmon, waste, and parasites such as sea lice affect wild fish, and discarded plastic from the farms, such as nets and ropes, ends up on beaches and in the sea.
(a)
Evaluate aquaculture as a way of meeting the growing demand for aquatic food.
[6 marks]
(b)
Explain how plastic debris affects marine environments and discuss how it can be managed.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).