Water Flashcards
Global Distribution of Water
Water is an essential resource for human life but the availability of freshwater supplies varies globally.
Global fresh water availability per person
○ 97% of global water is saline (salty ocean water).
○ 3% is fresh water suitable for human consumption, but 2% is locked up in glaciers and ice caps.
○ Only 1% is available for our expanding global population!
○ Places lacking water usually near the Equator, especially North Africa.
○ Canada and Iceland have the greatest fresh water availability per person.
Water surplus vs water deficit
Global water supplies are unevenly distributed because of variations in the amount of rainfall countries receive and the rate of evaporation and transpiration.
Tropical rainforests and mountainous areas receive more than they lose, resulting in a water surplus.
Countries in the Sahel region of North Africa receive little rainfall and have high rates of evaporation and transpiration, causing a water deficit.
Changing Water Use
Water supply and demand have changed in the past 50 years due to human intervention.
Changing global patterns
○ Asia (developing region) experienced the biggest increase from 1900, a dip after 1995, then an increase from 2010 onwards.
○ North America and Europe (developed regions) experienced a slightly lower rate of increase from 1980, which has remained fairly stable.
○ Africa and South America (developing regions) have a lower water consumption but this has gradually increased since the 1970s.
○ Oceania and Australia have the lowest water consumption by continent, and there is little change between 1900 and 2025.
Reasons for the pattern
As a country develops, the standard of living also increases. This leads to:
1. greater mechanisation in industry, using more water for manufacture (food and drink) and to cool down machinery
2. more labour-saving devices - washing machines use 80 litres of water per wash and dishwashers use 35 litres of water per wash
3. more water used for washing cars and watering gardens, and for luxuries like swimming pools and hot tubs
4. increased personal hygiene - we have moved towards a showering society, where people have regular showers, using 8 litres of water a day
5. increased leisure and tourism, with more water used in water parks, spas and for watering golf courses
Water Consumption Differences
People use water for agriculture, industry and domestic purposes. There are differences between the water consumption patterns of developing countries and developed countries.
Developed and developing countries
Average water consumption is an expression of the total water used in a country divided by its population. Water consumption in developed countries is high. On average, each person uses 1200 m³ per year. This is three times as much as in developing countries (400m³)
Reasons for differences in water usage - DEVELOPED COUNTRIES
- Agriculture
○ Drip feed sprinklers for watering crops control amount of water used.
○ Automated irrigation systems use lots of water. - Domestic
○ Piped water means people use lots of water for:
◘ domestic appliances
◘ baths and showers
◘ toilets.
○ Recreational use, e.g. swimming pools, hot tubs. - Industry
○ Water used for cooling machinery in factories.
Reasons for differences in water usage - EMERGING AND DEVELOPING COUNTRIES
- Agriculture
○ Ineffective irrigation. Hand pumps limit water use.
○ Surplus water left to drain away, evaporate or run off surface. - Domestic
○ Communal taps and wells used for washing clothes. Bathe in rivers. - Industry
○ Small-scale industries, e.g. basket weaving and pottery, use very little water.
Water Supply Problems: UK
There are three key reasons why the UK experiences water supply problems - you will need to know all of them.
Water supply problems in the UK
- Ageing infrastructure
Old water pipes can’t cope with the higher water pressures needed now (3.28 billion litres/year); sewage pipes are similar. - Seasonal imbalance
Some regions have greater difference between summer and winter rainfall than others, e.g. eastern Britain. Droughts cause problems for water supply companies, e.g. drier weather in 2009 = reduced reservoir levels in 2010. - Rainfall imbalance
Higher rainfall usually in upland areas (e.g. Scottish Highlands) with lower population density; lower rainfall in lowland areas (e.g. south-east, near London) where population density is higher.
Water Supply Problems: emerging or developing countries
Emerging or developing countries have their own water supply problems, including only having access to untreated water, pollution of watercourses and low annual rainall.
- Untreated Water
○ 663 million people - 1 in 10 - lack access to safe water;
○ Developing countries in Africa are the most affected by a lack of safe drinking water.
○ Without safe water, people cannot lead healthy, productive lives.
○ Drinking polluted water causes water-borne diseases and parasites.
○ An estimated 2000 people die every day from diarrhoea - governments can’t afford water treatment schemes.
- Pollution of Watercourses
Water can become polluted because of:
○ poor farming practices and unregulated use of fertilisers and pesticides
○ mining, e.g. copper mining in Zambia in 2006 caused health problems
○ lack of sanitation and education about human and animal faeces in water, leading to diseases.
