Water Security (AQA A Level Geography)

• Achieving water security means trying to obtain and manage sufficient water of a high enough quality to meet current and future needs
• This needs to be done sustainably, so that environmental and local community impacts are minimised
• Only 2.5% of water in the global hydrological cycle is freshwater
  • Of that, only 0.9% is easily accessible surface water
• Humans have extracted water from various sources, including rivers, lakes and aquifers
  • Technological innovation has seen new sources in the form of the desalination of seawater and recycling

Sources of Water for Human Use

Source	Explanation and Examples
River abstraction	Collecting water directly from a river is the oldest method of obtaining water Thames Water which serves London and southeast England gets 70% of its water from rivers
Reservoirs	Storage lakes, sometimes natural but often constructed, fed by rivers Welsh Water manages 91 reservoirs and obtains 95% of its water from river abstraction or reservoirs
Boreholes into the water table	Wells are sunk through permeable surface layers to penetrate the water table Groundwater is pumped to the surface either with machinery or through natural artesian pressure Thames Water obtains 30% of its water in this way
Pumping from aquifers	Aquifers are confined layers of saturated rock, deeper than the water table They are capped top and bottom by impermeable rock When bored into, the substantial pressure it is under forces groundwater to rise The Nubian Sandstone Aquifer System is underneath the eastern end of the Sahara Desert and is an important source of water for Egypt and surrounding countries It contains an estimated 150,000 km3 of groundwater
Snow and glacier melt	An important source for irrigation and urban industrial use for countries located near high mountains 60% of Iran’s freshwater comes from its melting glaciers Meltwater from glaciers in the Himalayas feeds the Indus, Ganges and Brahmaputra rivers which are used by 700 million people Climate change is threatening to cut off this source for many regions
Desalination	Evaporation of seawater to distil fresh water  Requires large amount of energy and produces salt as a by-product 40% of freshwater in Israel is desalinated
Water recycling and reuse	The process of treating wastewater using machinery or chemicals so that it can be reused, usually for industrial or agricultural purposes 90% of irrigation in the Valley of Mexico is from recycled water  This can also recharge groundwater supplies through percolation

Components of Water Demand

• The components of water demand describe how water is used in different ways: 
  • Agricultural use includes irrigation for crops and livestock management
  • Industrial use includes cooling for machinery and uses in product manufacture and processing
  • Domestic use includes water used in households and public buildings
• The factors affecting a place’s use of water include:
  • Level of development
  • Nature and structure of economy
  • Climate
  • Effectiveness of water collection methods
  • Effectiveness of water storage methods
  • Effectiveness of water distribution networks
  • Population total, growth rate and density

• These components vary over time:
• Global water demand increased by more than 700% in the 20th century
• It is forecast to increase even more sharply in the 21st century
• In 1900, agriculture accounted for 90% of global water consumption, with industrial and domestic use making up the other 10%
• Today, agriculture still accounts for 70%, with industry using 22% and domestic use at 8%
• Farm irrigation is the largest single human use of freshwater
• These components also vary over space:
• Water demand is greatest across Asia, North America and Europe
• Countries at different levels of development have different component ratios
• In the UK, 75% of water is used in industry, 22% for domestic and 3% for agriculture
• In Bangladesh, 95% is used for agriculture, 4% for domestic and only 1% for industrial use

Spatial variations in components of water demand

• There are various ways to describe the difficulty in obtaining enough freshwater of sufficient quality to serve the needs of a population

States of water security

• In 2014, 36 countries faced extremely high levels of water stress
• 1.1 billion people
• More than 80% of the water available to agricultural, domestic and industrial users is withdrawn annually
• Leaves businesses, farms and communities vulnerable to scarcity

Global water stress, 2019