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

Illustration of Earth’s water distribution: 97.5% saline, 2.5% freshwater; 1.6% locked in glaciers (68.7%) and groundwater (30.1%). 0.9% accessible: lakes, rivers, soil, etc.
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

World map with countries color-coded by percentage in six categories: Low (10%), Low-Medium (10-20%), Medium-High (20-40%), High (40-80%), Extremely High (>80%), and No Data.
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

A graph showing the global increase in water usage from 1901 to 2014, rising from 500 billion cubic meters to nearly 4 trillion cubic meters.
Graph to show increased demand for water   
  • The world’s population has tripled since 1922

  • This has increased the global demand for water

Two pie charts showing water abstraction from rivers, lakes, groundwater: Agriculture (67-93%), Domestic/Industrial (19-20%), Power (10-11%), Evaporation (3-4%).
Water use by sector
  • 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  

World map showing average daily income per person in various countries, color-coded: dark green for $2.00 or more, shades of green/blue for lesser amounts, and grey for no data.
Cost of bottled water

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