Water deficit (WJEC Eduqas GCSE Geography B): Revision Note

Specification link

This page covers section 3.3.2 of the WJEC Eduqas GCSE specification.

3.3.2 What happens when demand for water exceeds supply?

• The concept of over-abstraction and the reasons for water transfer schemes.

• The impact of over-abstraction and unsustainable use of water on people, the economy and environment.

• Coverage to include the impacts in countries at contrasting levels of development.

Over-abstraction

• Aquifers are where water is stored underground in layers of porous rock

• Precipitation filters through soil and rocks to reach the aquifers, where it is stored

  • This process is known as recharge

• The water is obtained by drilling boreholes or digging wells

• 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

• Many countries rely on groundwater as the main source of water

• This can lead to impacts such as:

  • Subsisdence

  • Water insecurity

North China Plain

• The North China Plain (NCP) is a densely populated agricultural and industrial region

• It includes parts of Beijing, Hebei, Henan, and Shandong provinces

• The main water source for the area in the past has been groundwater

Why is there so much abstraction of water?

• Demand for water in Beijing alone is 3.6 billion cubic meters 

  • The supply of freshwater in Beijing is 3 billion cubic meters

• The area receives less than 600 mm of precipitation per year

  • This falls mainly in the summer months

  • Eight months of the year have an average rainfall of less than 40mm

  • This means that in some years, the aquifers are not recharged

• Surface stores are often polluted

  • Groundwater is viewed as cleaner, though it may also be polluted

• Rapid urbanisation and a growing population increase the demand for water

• The digging of illegal wells increases the abstraction of water

• There is a significant water deficit

  • This has led to over-abstraction of groundwater

Water transfer

• To meet the demand for water, many countries have invested in water transfer schemes

• These are 'top-down' developments

  • Governments, businesses and local governments make decisions

• Dams and reservoirs are built to store water

  • The water is then transferred by pipes, canals and rivers from areas of water surplus to areas of water deficit

• Water transfer schemes have been used by countries at all levels of development

South North Water Transfer Project (SNWTP)

• A significant water transfer project in China was the SNWTP

• The project aimed to transfer 12 trillion gallons of water a year from the south of China to the area around Beijing

  • The central section was completed in 2014

  • Completion was planned for 2050

  • It was aimed to link China's four main rivers: the Yangtze, Yellow, Huaihe and Haihe

• The eastern and central routes are operational

• The western route is not completed, and no decision has been made regarding its completion

Impacts of unsustainable water use

• Many areas suffer significant impacts as a result of unsustainable water use

  • Unsustainable water use occurs when water is consumed or polluted at a rate faster than it can be naturally replenished

  • Over-abstraction of water is unsustainable

• Unsustainable water use is an issue in countries at all levels of development. It can lead to:

  • Water stress

  • Pollution

  • Groundwater depletion

Impact of water stress

• Water stress occurs when the available clean, accessible water supply is less than 1700 cubic metres per person per year

• The impacts of water stress include:

  • Agricultural impact

    • Water stress can reduce crop yields due to a lack of sufficient irrigation water, leading to food insecurity

  • Economic impact

    • Water shortages can disrupt industries, particularly those requiring significant water inputs like energy, textiles, and food production

  • Health impact

    • Low water quality in stressed regions leads to diseases like cholera and dysentery due to a lack of clean drinking water

Impact of pollution

• Water pollution occurs when harmful materials are in high enough concentrations to make the water unfit for use and/or harmful to the ecosystems

• Water pollution is an unsustainable use of the water

• The impacts of water pollution include:

  • Agriculture and aquaculture

    • Fish populations decrease

    • Contaminated seafood may be unsafe to eat

    • Using contaminated water for irrigation or livestock may lead to crop and animal deaths

  • Economic impact

    • Cost of water treatment

    • Higher costs of water for consumers

    • Loss of tourism due to polluted lakes and rivers

  • Health risks,

    • Waterborne diseases, including cholera and dysentery

    • Chemical pollutants can also lead to reproductive issues and increased cancer risk

Impact of groundwater depletion

• Groundwater depletion is a decrease in aquifer levels caused by abstracting more groundwater than is being replenished by rainfall

• This is unsustainable because eventually the water will run out

• The impacts of groundwater depletion include:

  • Agriculture

    • Crops fail

    • Lower yields due to reduced irrigation

    • Food insecurity

    • Higher irrigation costs

    • Increased salinity of water can affect crops

  • Economic impact

    • Factories and power stations reliant on water may face shortages

    • Tourism may be affected as water scarcity can impact resort facilities such as swimming pools

    • Subsidence leads to repair costs

  • Health risks

    • Reduced access to safe drinking water leads to health problems, such as dehydration

    • Pollution concentrations increase as there is less water to dilute the pollutant

Impacts of unsustainable water use in Spain

• Over-abstraction is a significant issue in Spain

• The main causes are:

  • Agriculture, especially in areas such as Almeria

    • Over 80% of Spain's freshwater is used for agriculture

  • Tourism, particularly in the south-east of Spain

  • Illegal wells

    • It is estimated that there are over 500,000 illegal wells in Spain, extracting groundwater

• This unsustainable water use leads to:

  • Higher water costs for users

  • Water shortages

    • In many areas in 2025, restrictions were put in place to reduce water use, including bans on filling swimming pools, watering gardens etc..

  • Poor water quality, including increased salinity

  • Land subsidence - In Murcia, it is estimated that the rate of subsidence has doubled between 2004-2008

  • Drying up of wetlands like Doñana National Park

• Industry and agriculture can adapt but costs are high and have included the building of desalination plants

Impacts of unsustainable water use in India

• Unsustainable water use in India is the result of factors including:

  • Increased demand due to population growth

    • India's population is now the largest of any country in the world

    • India has 18% of the world's population, but only 4% of the world's freshwater (2025)

  • Poor water management, including inefficient irrigation systems and poor waste disposal

    • Over 90% of sewage enters the rivers untreated

    • Industries dump 300-400 million tonnes of waste into the rivers

  • Increased levels of water pollution from industry, domestic and agricultural activities

• This unsustainable water use leads to:

  • Limited access to clean water for many people

    • Over 35 million people lack access to safe water

  • Health impacts are severe

    • An estimated 37.7 million people are affected by waterborne diseases each year

    • In one informal settlement in Mumbai, 30% of deaths were the result of waterborne illness

  • A decrease in the water table of up to 4 meters in some areas

  • Agriculture suffers decreased yields

    • In the Sonipat district, farmers report crop failures, which they attribute to water pollution