Water Scarcity (DP IB Geography): Revision Note

Physical & Economic Water Scarcity

• Water scarcity is when the supply is below 1000m³ a year per person

• There are two types of water scarcity:

  • Physical water scarcity 

    • This affects about 20% of the world’s population (1.2 billion)

  • Economic water scarcity 

    • This affects about 25% of the world’s population (1.6 billion)

• Physical water scarcity depends on a variety of factors, including:

  • Level of precipitation

  • Population growth

  • Water availability

  • Water demand

• Economic water scarcity is the result of:

  • Poor management of water resources

  • Lack of water infrastructure

Drought

• Drought is an extended period of dry weather that leads to extreme dryness:

  • Absolute drought

  • Partial drought

• Drought is caused by:

  • Changes in atmospheric circulation, such as a shift in the position of the Inter-tropical Convergence Zone (ITCZ) or El Niño, lead to:

    • A lack of precipitation as a result of short-term changes or longer-term trends 

    • The lack of rainfall is often combined with high temperatures, which increases evaporation 

• The severity of droughts depends on the length of the drought and the extent of the shortage

Impacts of drought 

• The impacts of droughts include:

  • Increase in animal mortality:

    • Over half a million livestock (cattle, goats) were affected by drought in Somalia in 2022

  • Increase in forest fires as the vegetation is dry and catches fire easily

  • Bans on hose pipes for watering gardens in higher-income countries

  • Potential for conflicts over water supply, particularly where countries share a river basin

  • Children in rural areas in low-income countries often miss out on school as they are responsible for collecting water (may have to walk miles to the nearest water source)

  • Lack of food due to:

    • Lower crop yields because the plants cannot be irrigated

    • Livestock deaths due to a lack of water

  • Damaged ecosystems and loss of habitats

  • Reduced economic development as water is not available for industry 

Water Quantity & Water Quality

Water quantity and water quality

• Water quantity depends on several factors:

  • Rates of rainfall

  • Groundwater and river flows 

  • Transpiration

  • Evaporation

Freshwater resources in the world

• Globally, around 12,500 cubic kilometres of water are available for human use on an annual basis

• There are 6600 cubic metres per person per year available for individual human use

• If current trends continue, there will only be around 4800 cubic metres available per person in 2025

• The world’s available freshwater supply is not distributed evenly around the globe:

  • 75% of annual rainfall occurs in areas containing less than two-thirds of the population

Map to show water stress

• Water stress occurs when water supply is less than 1700 cubic metres per year

• Water stress can cause problems for food production and further economic development

• UNICEF claim that nearly four billion people will be affected by water stress in 2025

Water use

• The world’s population has tripled since 1922

• This has increased the global demand for water

• Globally, agriculture is the largest user of water 

• Disputes over water scarcity may lead to more armed conflicts

• The World Health Organisation claim that 3.6 billion people do not have access to safely managed sanitation in their home

• Rural areas are the worst affected, 8 out of 10 people who continue to lack access to safe drinking water 

Water quality

• In 2022, at least 1.7 billion people in the world drank water that had been contaminated with faeces

• Microbiologically contaminated water can transmit diseases such as cholera

• One million people are estimated to die each year from diarrhoea due to unsafe drinking water, sanitation and hand hygiene

• Water quality may be affected by:

  • Use of fertilisers and pesticides from agriculture

  • Sewage water

  • Industrial processes

• Access to safe water may be limited by availability, infrastructure and cost

• Urban areas have better access to clean water than rural areas

• The cost of water when connected to water mains is less expensive than when customers have to pay 

Cost of bottled water