• 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

Sources of water

• 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

Water Use?

• 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

• 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 m^3?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 production of goods and energy production
  • Increasing use in?agriculture?- more water is needed for livestock

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

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 1700m^3?a year per person
  • Water scarcity is when the supply is?below 1000m^3?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 north USA
  • Russia