Unit 4: Water and its Management:

2-Mark Question

1. Define water stress.

Model Answer:

Water stress occurs when the demand for water exceeds the available amount of water, or when water supplies are insufficient to meet the needs of the population.

Why this works:

• Identifies insufficient water availability (1 mark)

• Links this to demand exceeding supply/population needs (2nd mark)

4-Mark Question

2. Explain two environmental impacts of water pollution.

Model Answer:

Loss of aquatic biodiversity: Pollutants such as sewage and chemicals can reduce water quality, causing the death of aquatic organisms and reducing biodiversity.

Eutrophication: Fertilizers containing nitrates and phosphates can enter rivers and lakes, causing excessive algal growth. When algae decompose, oxygen levels fall, which can kill fish and other aquatic organisms.

Why this works:

• Two distinct impacts → 2 marks

• Each impact is explained through cause and effect → 2 more marks

• Uses specific terms such as eutrophication, nitrates, phosphates and oxygen depletion.

6-Mark Question

3. Discuss the advantages and disadvantages of building dams to manage water resources.

Model Answer:

Dams can store large quantities of water, providing a reliable supply for domestic use, agriculture and industry during periods of low rainfall. Reservoirs can also provide water for irrigation, increasing agricultural production. In some cases, dams are used to generate hydro-electric power, producing electricity without burning fossil fuels.

However, reservoirs can flood large areas of land, destroying habitats and agricultural land and forcing people to relocate. Dams can also alter the natural flow of rivers and interfere with fish migration, damaging downstream ecosystems. Sediment may accumulate behind the dam, reducing the amount of water that can be stored over time.

Overall, dams can provide important water supplies and other benefits, particularly in areas with seasonal rainfall, but their environmental and social impacts mean that careful planning and management are essential.

Why This Works:

• Gives multiple advantages and disadvantages

• Explains the consequences of each point

• Covers social, economic and environmental impacts

• Ends with a balanced judgement

8-Mark Question

4. Describe methods of conserving water and evaluate their importance in managing water resources.

Model Answer:

Water can be conserved in several ways. In agriculture, drip irrigation delivers water directly to the roots of crops, reducing evaporation and water wastage compared with some traditional irrigation methods. Farmers can also use sprinklers or irrigation systems during cooler periods to reduce evaporation. In urban areas, repairing leaking pipes and water systems prevents large quantities of water from being lost. Households can conserve water by using water-efficient appliances, fixing leaking taps and reducing unnecessary water use.

Wastewater can also be treated and reused for purposes such as irrigation or industrial processes, reducing the demand for fresh water. Rainwater harvesting allows rainfall to be collected and stored for later use, reducing pressure on rivers and groundwater supplies.

Water conservation is important because freshwater supplies are limited and demand is increasing due to population growth, agriculture, industry and urbanization. However, conservation methods may require investment in infrastructure and technology, and some methods may be difficult for poorer communities to afford.

Overall, water conservation is essential for reducing pressure on freshwater supplies. The most effective approach is likely to combine efficient agricultural methods, improved infrastructure, wastewater reuse and changes in people's behavior.

Why This Works:

• Describes several specific conservation methods

• Explains how each reduces water use

• Links conservation to increasing demand and limited freshwater

• Includes a limitation: cost/infrastructure

• Provides an evaluative conclusion

10-Mark Question

5. Assess the effectiveness of different strategies for managing increasing demand for freshwater.

Model Answer:

Increasing demand for freshwater can be managed through water conservation, improved irrigation, wastewater treatment, rainwater harvesting, desalination and the construction of reservoirs. Water conservation can reduce demand by encouraging households and industries to use water more efficiently. For example, repairing leaking pipes prevents water from being lost before it reaches consumers.

Agriculture is particularly important because it uses large quantities of freshwater. Drip irrigation can reduce water wastage by delivering water directly to crop roots, while drought-resistant crops can reduce the amount of water needed for agriculture. These methods can be particularly effective in areas where agriculture is the main user of freshwater.

Wastewater treatment and reuse can provide an additional water supply without requiring the extraction of more freshwater. Desalination can also provide freshwater from seawater and is particularly useful for countries with limited freshwater supplies and access to the sea. However, desalination requires large amounts of energy and can be expensive. The concentrated saltwater waste produced can also damage marine ecosystems if it is poorly managed.

Dams and reservoirs can store water during periods of high rainfall and provide supplies during dry periods. However, they can flood habitats, displace communities and alter river ecosystems. Therefore, building more dams is not always the most sustainable solution.

Overall, the most effective strategy depends on local conditions. Water conservation and efficient irrigation are generally highly sustainable because they reduce demand rather than simply increasing supply. However, in areas with severe water shortages, combining conservation with wastewater reuse, rainwater harvesting and carefully managed desalination may provide the most reliable long-term solution.

Why This Works:

• Covers multiple water-management strategies

• Explains how each works

• Evaluates both benefits and environmental/economic limitations

• Recognizes that effectiveness depends on local conditions

• Ends with a clear overall judgement

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