The global distribution of fresh water

Fresh water, essential for life, is not evenly spread across the planet. It makes up only a small fraction of Earth's total water resources, with the majority being saline water found in seas and oceans.

Proportion of fresh water on Earth

• Limited availability - Only about 3% of the water on Earth is fresh water.
• Dominance of saline water - The remaining 97% is salty water, primarily located in oceans and seas, unsuitable for most human uses without treatment.

Storage locations of fresh water

Fresh water is stored in various forms and locations across the globe. Understanding where it is held helps explain why its distribution is uneven and why access can be challenging in some regions.

Key storage forms of fresh water

• Surface water - Found in lakes and rivers, easily accessible but limited in volume.
• Groundwater - Stored underground in aquifers, which are water-holding rocks.
• Frozen water - Locked in ice caps and glaciers.
• Atmospheric water - Exists as clouds and water vapour, a small but critical part of the water cycle.

Factors affecting fresh water availability

The availability of fresh water varies widely across the world due to a combination of natural and human factors.

Influences on fresh water availability

• Natural conditions - Depends on rainfall amounts, evaporation rates, and the presence of water sources like rivers or lakes.
• Regional climate - Areas with high rainfall and cooler temperatures experience less evaporation, preserving water, while dry climates often face shortages.
• Infrastructure - Access to water treatment facilities is crucial to ensure water is clean and safe for human consumption, particularly in arid regions where such facilities may be scarce.
• Local variations - Even within a single country, water availability can differ significantly between areas due to geographic and climatic differences.

Patterns of water surplus and deficit

The unequal distribution of fresh water leads to some areas having more than they need, while others struggle to meet basic requirements.

Characteristics of water surplus

• Abundant resources - Occurs in regions with plentiful water sources and low demand.
• Low population pressure - Some countries, like Canada, have vast fresh water resources relative to their population size. For instance, Canada holds approximately 7% of the world's renewable fresh water but accounts for just 0.5% of the global population.

Characteristics of water deficit

• Insufficient supply - Found in areas with low water availability coupled with high demand.
• Seasonal challenges - Certain regions face temporary deficits, especially during dry periods when rainfall is scarce, yet water needs for agriculture remain high.

Changes in water supply and demand since the 1960s

Over the past few decades, the balance between water supply and demand has shifted significantly. Since 1960, global water consumption has more than doubled.

Supply factors impacting water availability

• Over-abstraction - Groundwater and aquifers are being depleted faster than natural processes can replenish them.
• Pollution - Contamination from agricultural and industrial chemicals makes water in lakes and rivers unsafe for use.
• Climate change - Altered weather patterns have made rainfall less predictable in some areas.

Demand factors increasing water needs

• Population growth - A rapidly increasing global population means more people require water for daily use.
• Industrial expansion - Growth in industries demands more water for manufacturing and other processes.
• Agricultural practices - More farmers are turning to irrigation to water crops, rather than depending on rainfall.
• Lifestyle changes - Wealthier populations often adopt water-intensive habits, such as using appliances that consume large amounts of water.