Water Supply and Use (Cambridge International IGCSE Geography)

Global Water Supplies

Spec point — 3.6.1 · Describe methods of water supply & the prooprtions used for agriculture, domestic & industrial purposes in countries at different levels of economic development

Global water supply

• Only 2.5% of the water on Earth is freshwater

• Approximately 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

  • This is not evenly distributed across the globe—Canada contains more lakes than the rest of the world combined

Pie chart showing sources of water.

(note: due to rounding of figures, the % on the pie chart to the right adds up to 99.9%)

Water supply

• The supply of water humans use comes from three main sources:

  • Lakes and rivers
  • Aquifers
  • Reservoirs

• Other sources of water supply include:

  • Desalination
  • Rainwater harvesting—collecting water that falls as precipitation

Groundwater/aquifer

• Water stored underground

• The water has filtered through soil and rocks

• It is obtained by drilling boreholes or digging wells

• When all the rock is fully saturated with water, it is an aquifer

• Groundwater may also come to the surface as a spring

• Issues with groundwater/aquifers include:

  • Overuse or over-abstraction of water in some areas means that aquifers do not have time to recharge through precipitation
  • Pollution from industry, agriculture and domestic waste can leach into the groundwater

Surface water

• Water is stored in lakes, reservoirs, and rivers

• Issues with surface water include:

  • Pollution from industry, agriculture and domestic waste can enter the water system through surface runoff
  • Dams are used to store water in reservoirs, but the construction of dams has slowed due to a lack of suitable sites and concerns regarding the environmental impact

Desalination

• The removal of salt from seawater means that it can be used for domestic, agricultural and industrial purposes

• Issues with desalination include:

  • Expensive to set up and run
  • Desalination plants use a lot of energy

Global water use

• 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 MEDCs or LEDCs

Water demand

• The global demand for water is increasing
• Between 1934 and 2014, demand increased from 1 trillion m³ to 4 trillion m³

Graph depicting global freshwater use from 1900 to 2014

Water use in MEDCs

• 11% Domestic
• 30% Agriculture
• 59% Industry

Water demand in MEDCs

• The water demand in MEDCs is higher than in LEDCs for the following reasons:

  • Improving **living standards—**people have more appliances/sanitation that use water
  • Increased use of water in** leisure and tourism—**water parks, golf courses
  • Increased** urbanisation**
  • Increasing **industry—**water is needed for the production of goods and energy production
  • Increasing use in** agriculture—** more water is needed for livestock

• The largest use of water in MEDCs tends to be industry

Water use in LEDCs

Water use in LEDCs

Water demand in LEDCs

• Unlike MEDCs, water use in LEDCs is mostly used for agriculture
• Many people are still dependent on agriculture
• There is far less industry in many LEDCs so the demand for water for industrial processes is low
• Many people in LEDCs do not have access to piped water and, as a result, are more cautious with water use

Worked Example Study Fig 1, which is a map showing information about the percentage of the population in each country with access to clean drinking water.

Fig 1

Describe the distribution of countries where 75% or less of the population have access to clean drinking water.

[3 marks]

Final answer: **Answer **

• Mainly/most in Africa** [1]**
• Except Egypt and South Africa/except in North and South [1]
• A few/some in Asia [1]
• Near/on the equator, mainly in the tropics, between the Tropics of Cancer and Capricorn, Central Africa, and sub-Saharan Africa [1]
• Uneven/clustered [1]

Exam Hint When describing the distribution from a map, ask yourself the following questions:

• What is the general pattern?
• Does the pattern relate to anything else for example, the location of LEDCs and MEDCs?
• Are they near the equator or further away?
• Is the pattern uneven or clustered?

Use map features to help with your description: place names (countries and continents), compass rose, latitude and longitude, the equator and the tropics.