Virtual water refers to the water used in the production of agricultural and industrial products. Large amounts of water are required to produce many goods - for example, 1kg of beef requires 16,000kg of water. Countries import virtual water when they import water-intensive goods produced elsewhere. This is important for water-stressed countries. For example, in Southern Africa the average annual runoff in South Africa is 45.2km3/year, while Lesotho contributes an additional 5.2km3/year through water transfers. Several countries in the region are already experiencing water stress according to common definitions. The document provides statistics on water availability and usage in several Southern African countries.

1. Virtual Water
Some Definitions and Figures

2. Virtual Water
• The water used in the production process of an agricultural or
industrial product.
• 1kg of grain requires about 1000-2000 kg of water (or 1-2 m3)
• 1 kg of cheese requires about 5000kg of water
• 1 kg of beef requires 16000 kg of water
• A computer chip weighing 2 g requires 32 kg of water

3. Virtual Water and Trade
• Water, food, trade nexus
• Virtual water is exogenous to the country that imports it by
importing products that used that water to be produced.
• Water stress countries (user vs producer)
• Globalization
• Regional water security

4. An Example: Southern Africa
Rainfed crop potential in southern Africa (IWMI, 2001)

5. Lesotho - South Africa
• In South Africa, the average annual runoff is 45.2 km3/y, about 10% of
annual rainfall, 40 km3/y are generated within the country, while 5.2
km3/y come from Lesotho. The ground water resources are estimated
to be 4.8 km3/y, of which about 1.79 km3/y were exploited in 1980
(FAO, 1995).

6. Water stress (Heyns 2002)
Levels of stress Withdrawal/availability ratio (%)
Low <10
Moderate 10-20
Medium 20-40
High 40-60
Catastrophic >60
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7. Water endowments for some countries
Country South Africa (1995-2000) Zimbabwe (1995-2000) Zambia (1995-2000) Mozambique (1995-2000)
Water Availability TOTAL km3/y 50.01 20 116 216
Total freshwater withdrawal km3/y 13.31 1.22 1.71 0.61
Water Availability per capita m3/p/y 1,208 1,711 12,001 12,746
Water Availability per capita - projection
2025
m3/p/y 1,077 1,108 8,526 4066
Dependency ratio % 10.4 29.5 30.9 53.7
Estimated year per capita withdrawal m3/p/y 288 98 187 31
Urban supply 2000 % 92 100 88 86
Rural supply 2000 % 80 77 48 43
Improvement in urban supply Since 1970 Yes Yes No Yes
Improvement in rural supply Since 1970 Yes No (-3%) No Yes
Agriculture % 62 79 77 89
Domestic % 17 14 16 9
Industry % 21 7 7 2
Cultivated land ha - - 1,029,570 3,600,000
Cultivable land 18,320,000 - 16,350,000 36,000,000
Full or partial control irrigation: equipped
area
ha 1,270,000 116,577 46,400 106,710
Irrigated from groundwater % 18 - 5.4 -
Irrigated from surface water % 82 - 94.6 -
Total irrigated grain production t 1,320,000 - 81,500 -
As a % of total grain production % 9 - 5.4 2
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8. Katse

9. Mohale