water resources

Answer: Water surplus occurs where rainfall exceeds demand (e.g. Canada, Scandinavia - high rainfall, low population density). Water deficit occurs where demand exceeds supply (e.g. Middle East - low rainfall, high population and agricultural demand). The balance depends on physical factors (precipitation, geology, seasonality) and human factors (population density, wealth, industrialisation, agriculture). Some regions have seasonal surplus and deficit (monsoon areas).

Answer: Water surplus occurs where rainfall exceeds demand (e.g. Canada, Scandinavia - high rainfall, low population density). Water deficit occurs where demand exceeds supply (e.g. Middle East - low rainfall, high population and agricultural demand). The balance depends on physical factors (precipitation, geology, seasonality) and human factors (population density, wealth, industrialisation, agriculture). Some regions have seasonal surplus and deficit (monsoon areas).

Answer: Factor 1: Wealth - richer populations consume more water for swimming pools, gardens, and appliances. The USA uses 5,700 litres/person/day compared to Mali's 1,200 litres. Factor 2: Agriculture - farming accounts for 70% of global water withdrawals; irrigation-intensive countries use much more water. Factor 3: Climate - hot, dry climates increase demand for irrigation and cooling, while cooler, wetter climates need less.

Answer: Advantages: Lesotho gains $50 million/year in revenue and hydroelectric power; South Africa receives reliable water for 6 million+ people in Gauteng; infrastructure improvements. Disadvantages: 30,000 people displaced; lost farmland; inadequate compensation; health problems from construction; reduced river flow downstream. Overall, the project benefits both countries economically but the social and environmental costs for Lesotho's local communities are significant.

Answer: Desalination is energy-intensive (3-4 kWh per cubic metre), making it expensive and carbon-intensive unless powered by renewables. The brine waste produced is highly concentrated salt that damages marine ecosystems. It is only viable for wealthy coastal countries - Saudi Arabia can afford it, but many water-scarce LICs cannot. It does not address the root causes of water scarcity (overconsumption, poor management). It should be part of a strategy alongside conservation and efficiency improvements.

Answer: Water conservation is more sustainable long-term because it reduces demand rather than creating new supply. Strategies like drip irrigation (saves 70%), greywater recycling (saves 30-50%), and metering (saves 15-20%) are cheaper and have fewer environmental impacts than dams or desalination. However, conservation alone may be insufficient in areas of absolute scarcity (e.g. Middle East) where supply must also increase. The most effective approach combines both: reducing demand through conservation while developing sustainable new supplies (e.g. Singapore's Four National Taps approach).

Answer: Strategy 1: Drip irrigation delivers water directly to plant roots, reducing evaporation by up to 70% compared to flood irrigation. Strategy 2: Greywater recycling reuses water from sinks and showers for irrigation and toilet flushing, reducing household consumption by 30-50%. Strategy 3: Rainwater harvesting collects rainwater from roofs for domestic and agricultural use, providing an affordable, low-technology solution particularly suitable for LICs.