4.3 Water Debt

If the amount of ground water withdrawn exceeds natural inflow, there is a water debt . In such cases, water should be considered as a non-renewable resource that is being mined. As the world’s population and industrial production of goods increase, the use of water will also accelerate. The world per capita use of water in 1975 was about 700m³ /year giving a total human use of 3850 km³/year. In 2006 the world use of water was about 6000 km³ / year, which is a significant fraction of the naturally available fresh water. [see reference 13]

 

Figure 4.3.1 Water debt for of the most indebted countries [see reference 14]

Figure 4.3.1 sourced from The ImpEE Project, The Cambridge-MIT institute. The ImpEE wesbite is designed as an educational resource. It may be reproduced, modified and used freely for educational purposes
http://www-g.eng.cam.ac.uk/impee/?section=topics&topic=water&page=slideshow

Some water-stressed countries withdraw considerably more water than is renewed annually, leading to significant ‘water debt’. Countries are arranged here in descending order of water debt severity.

Kuwait is currently the world’s most water scarce nation and also the worst water debt country, with an annual renewable freshwater supply of approximately 0.02km³/year and an annual freshwater withdrawal of around 0.54km³/year (2700% of available renewable supply). Saudi Arabia extracts the greatest volume of water (14.62 km³/year) beyond its renewable supply (2.4km³/year) and uses 7 times more than it has available, but UAE (1.91km³/year debt and consumption 10 times renewable supply) and Libya (4km³/year and nearly 8 times supply) are also in severe water debt.

However, even relatively water-rich countries can exceed their renewable supply; Uzbekistan has approximately 50.4km³/year renewable available freshwater, but withdraws around 58.05km³/year (115% of available supply). Uzbekistan has experienced the detrimental effects of this unsustainable over-use of freshwater and has witnessed the deterioration of the Aral Sea and its associated industry.

In comparison:

• USA withdraws only around 20% of available renewable supply
• UK withdraws only around 10% of available renewable supply
• Canada withdraws only around 1.5% of available renewable supply
• Brazil withdraws only around 0.5% of available renewable supply

Water-debt countries and regions meet their water withdrawals beyond the renewable supply in a number of ways, including: drawing water across political boundaries, or depleting ‘fossil aquifers’ in some cases causing not only extraction of ancient groundwater reserves, but also causing irreparable collapse of the geological structure, thus preventing future recharge.

Energy-rich but water-poor countries, such as the water-stressed and water-debt oil-producing countries of the Middle East may use desalination techniques to produce freshwater from sea water, which will be discussed next.