Global Supply of Fresh Water (Edexcel GCSE Geography A)

Global Distribution of Fresh Water

How much fresh water is available on Earth?

• Over 70% of the Earth is covered by water

• Only a proportion of that is fresh water and not all of this is available as drinking water

Global water stores

What is the distribution of fresh water?

• The availability of freshwater varies across the globe

• Areas with the lowest availability of fresh water are in areas such as North Africa, the Middle East and India

• Canada, Iceland and Norway are some of the countries with the highest availability of fresh water

Global freshwater availability per person

Water Surplus & Deficit

What are a water surplus and a water deficit?

• Water deficit occurs when water demand is higher than supply

• Water surplus is when there is greater water supply than demand

Water shortages (deficit)

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

• A 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

Global water surplus and deficit

• 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 stress can be measured using the Water Exploitation Index, this is given as a percentage

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

Changing Supply & Demand

How has water demand changed over the last 50 years?

• Over the last 50 years, human intervention has led to changes in the supply and demand of water

• The changes depend on the location

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Global water consumption by region

• Factors that increase demand include:

  • Increasing population

  • Growth of industries which use large quantities of water

  • More appliances, such as washing machines, which use water

  • Greater use of water for homes and leisure activities such as:

    • Washing cars

    • Watering gardens

    • Hot tubs

    • Swimming pools

    • Golf courses

  • Increased use of showers and baths

  • Growth of agriculture to feed the increasing population

    • Particularly meat production, which uses more water

How has the water supply changed over the last 50 years?

• Climate change has led to change patterns of precipitation

  • Reduced precipitation in some areas

  • Rainfall at unusual times of the year in other areas

• Greater abstraction of water

• The building of dams and reservoirs 

  • These impact the supply of water to other areas

  • May reduce supply of water downstream

    • The Grand Renaissance Dam in Ethiopia reduces water supply to Sudan and Egypt