Virtual water - What is it?

Whilst researching water and food in Africa for my last blog post, I came across the concept of virtual water in several papers. As this is a new idea to me, I have decided to write a post on my findings upon further research.

A country’s economy can be either open or closed. A closed economy is self-sufficient, with no trading activity with other economies. In contrast to this, an open economy readily participates in international trading to meet the country’s needs and development goals. This means that a country can import resources that are scarcely available and export commodities that are in abundance.

The African Union’s Agenda 2063 and the UN 2030 Agenda for Sustainable Development go hand-in-hand to ‘build a prosperous and united Africa’ [SDGC in Africa]. Countries such as South Africa and Zimbabwe have arid climates and are therefore increasingly water-stressed. This threatens the food security of these countries as water availability and food production are intrinsically tied. In such regions, food self-sufficiency may not be achieved, resulting in the need for imports.

As importing real water is not feasible due to the vast infrastructure required and distance between countries, the idea of virtual water was introduced. In simple terms, virtual water is the total amount of water required in the production of a product or service. It is termed ‘virtual water’ as the water is not necessarily found within the final product.

A country experiencing water scarcity can thus, import water-intensive products, saving water that would have originally been used in its production. This may enable a nation to achieve water security in the future. Hoekstra and Hung calculated in their research that the global volume of crop-related international water trade between 1995 and 1999 was 695 Gm³ yr^-1 [Hoekstra and Hung, 2005]. From this, they were able to estimate that 13% of the water used in the production of crops was for export.

African agriculture is vulnerable to the extreme spatial variation of rainfall, making it difficult for farmers to obtain consistent crop yields. Moreover, areas such as South Africa has an average rainfall of 451mm per year which is lower than the minimum rainfall of 500mm per year. This puts South Africa in the ‘water-stressed’ category and implies that agricultural yields will be unsuccessful.

It was also estimated that rain-fed crop yields will decrease by 50%, resulting in some African countries spending 5-10% of their GDP to adapt to these effects of climate change [Konar and Caylor]. Furthermore, the International Panel on Climate Change states that even in the absence of climate change, the current population trends of water usage indicate that more African countries will surpass the limits of their economically usable, land-based water resources before 2025 [Climate Change 2007].This highlights the need for African countries to partake in international virtual water trade to reduce the potential risk of water scarcity.

Figure 1 - shows the African trade network for virtual water. Each nation is assigned a specific colour with trade links being in the colour of the exporting nation. [Source]

Africa trades products both, internally and internationally. Research shows that the trade network within Africa is greater than the trade connections between Africa and the rest of the world. For example, the volume of virtual water traded is 3.59km³ and 1.18km³ within African countries and to the rest of the world, respectively.

Figure 1 is a visual representation of the internal African trade network. It is evident from figure 1 that South Africa is a major exporter, trading 1.12km³ of virtual water to other African nations. Most of South Africa’s produces are supplied to Zimbabwe as shown by the thickness of trade link. This is different from data collected between 1995 and 1999, where Zimbabwe had net export and South Africa had net import [Hoekstra and Hung, 2005]. The reasons for such changes may be due to economic development and political changes.

In conclusion, I think the concept of virtual water is beneficial to many countries within Africa as water-intensive products can be imported, allowing the use of the remaining water elsewhere. For example, statistics show that one tonne of wheat imported represents 1300 tonnes of water [Kreith, 1991]. The trading of virtual water, internationally and within the continent will aid the African nations to achieve the UN Sustainable Development Goals, such as the sixth goal, to ‘ensure availability and sustainable management of water and sanitation for all’ [UN SDG]. In addition to this, the flow of virtual water, in the form of grain imports into the Middle Eastern region of Africa was calculated to be equivalent to the annual flow of the River Nile. This averts conflict between nations as water insufficiency has been an issue since 1970.