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/