Water Uses, Demand & Supply (Edexcel IGCSE Geography)

Water Uses

• Only 2.5% of the water on Earth is freshwater

• 68.7% of freshwater is stored in glaciers and ice sheets and 30% is groundwater

• The remaining 1.3% of freshwater is in rivers, soil moisture, lakes and the atmosphere

• Global water use by sector is: 

  • 70% agriculture - irrigation of crops and water for livestock

  • 20% industry - producing goods and generating energy

  • 10% domestic - toilets, cooking, cleaning, washing

• The use by sector varies across countries depending on whether they are developed, emerging or developing

• In developing and emerging countries most water is used for agriculture

• The use of water in leisure and tourism is increasing, particularly in developed countries

• In developed countries most water is used for industry

Rising Demand for & Supply of Water

• Demand is the amount of water requested by users to meet their needs

• Supply is the amount of water available

• Water balance is the difference between supply and demand

• Countries may have a deficit (greater demand than supply) or surplus (more supply than demand)

Water Demand

• The global demand for water is increasing

• Between 1934 and 2014 demand increased from 1 trillion m³ to 4 trillion m³

Water Supply

• The supply of water comes from three main sources:

  • Lakes and rivers

  • Aquifers

  • Reservoir

• The reasons for increased demand include:

  • Improving living standards - people have more appliances/sanitation which use water

  • Increased use of water in leisure and tourism - water parks, golf courses

  • Increased urbanisation 

  • Population growth - the more people there are, the more water is needed

  • Increasing industry - water is needed for the production of goods and energy production

  • Increasing use in agriculture - more water is needed for livestock

Areas of Water Shortages & Surpluses

Water Shortages (Deficit)

• Many areas of the world have water shortages (deficits)

• Water deficit can be due to:

  • Low supply - lack of precipitation, high levels of evaporation, poor water management

  • High demand - increasing population, industry and agriculture

  • A combination of low supply and high demand

• Areas with the greatest water-deficit include:

  • Australia

  • North, East and South Africa

  • Middle East

  • West USA

  • Parts of South America 

  • India

• Many of these areas have a deficit due to low precipitation throughout the year 

• In some areas demand is greater than supply due to increasing population, industry and agriculture

• There are different levels of water shortage - these are water stress and water scarcity:

  • Water stress occurs when the supply of water is below 1700m³ a year per person

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

Water Surplus

• Some areas of the world have a water surplus 

• Water surplus can be due to:

  • High supply - high precipitation, low evaporation rates, effective water management

  • Low demand - low population, effective water management, low temperatures

  • A combination of high supply and low demand

• Areas with a surplus include:

  • North-east Brazil in the Amazon rainforest

  • Canada and parts of the northern USA

  • Russia