Water Uses, Supply and Demand

Sources of pollution

•  Agriculture
  • Farm silage and slurry from farm animals
  • Fertilizers/pesticides

•  Industry
  • For cooling machines and returning it to source at high temperature
  • Oil spillages
  • Toxic substances

•    Domestic purposes
  • Discharge of untreated sewage
  • Using river for watching/ bathing
  • Emptying chlorinated water from pools

Uses of water

• 3% of world’s water supply is fresh water. 75% of fresh water is stored within glaciers while 20% within ground water storage.
• Domestic uses- cooking, washing, flushing toilets drinking.
• Industrial uses- 300 litres of water required for 1 litre of beer. 2400 litre of water required for a hamburger. 400000 litre of water required for 1 tonne of paper.
• Agriculture- irrigating crops provide drinking water to livestock.
• Leisure activities- swimming pools and watering golf courts.
• Consumption- the amount of water used. ( measures the level of demand for water).

Managing supply of clean water

• Collection: wells, lakes, rivers, reservoir
  • Treatment: aim to the raw water so it can be consumed by people. Substances removed are used for other purposes like producing fertilizers.
  • Chlorination, aerating, sedimentation, filtration, disinfection

•  Delivery
  • In most countries, water is delivered to houses and factories through pipes. However, in some countries, water is obtained from wells

Causes of flooding

• Cutting down of trees, reducing interception so more surface runoff.( Deforestation)
• Urbanisation- more concrete which is impermeable and drains so water enters river more quickly.
• Agriculture- the risk of flooding when leaving the soil bare.
• Global warming- melting of glaciers leading to a rise in water level. Also, higher frequency and severity of storms and rainfall.

Reasons for the increasing demand for water

• Rapid population growth- grown from 5.3 billion to 6.8 billion people in the world from 1990 to 2010.
• Improving standards of living- increase number of water- intensive activities.
• Increase in agricultural output- in response to the increasing population so more water is used for agricultural purposes.
• Industrialisation- more factories leads to higher consumption of water for industrial purposes, e.g. used for cooling machines and as a raw material.

Key points to note about water supply around the world

• Water deficit areas- where water balance is negative so water demand exceeds water supply.
• Water surplus areas- where water balance is positive so water supply exceeds water demand.

Source: https://www.acceleratedstudynotes.com/2012/10/01/igcse-geography-water-quality/