Africa's Virtual Water Trade

Virtual water refers to the water that is ‘hidden’ or embedded in products of consumption such as food or textiles. In terms of food, it is the precipitation (green water) or irrigation water (blue water) used to grow crops, the water used for harvests, the water used to clean and remove dirt from produce, and the water used to transport food to its destination. Global virtual water flows of traded agricultural and industrial products were 2,320 Gm3/year between 1996 and 2005. 76% of this virtual water flow was the international trade of crops or crop derived products (Hoekstra and Mekonnen, 2012). Why is virtual water important and how does it relate to countries in Africa?


Figure 1 – Virtual water (VW) imports and exports of major grains between Africa and its trading partners from 2000 to 2020. Values shown are quantified in Bm3 (Hirwa et al., 2022).

As mentioned in the previous blogs, water scarcity is already threatening the population of Africa and climate change is causing varied patterns of precipitation, significantly straining countries’ agricultural systems and their ability to feed a growing population. In order to survive these conditions, farmers have to be smart about the crops they grow and the food they import. For example, 1827 litres of water is needed to produce a kilogram of wheat but 287 litres of water is needed to grow a kilogram of potatoes (Mekonnen and Hoekstra, 2011). The trading of these goods is essentially the trading of virtual water, so to maintain food security under conditions of water scarcity and stress, nations within Africa should import water intensive cereal crops, but grow and export less water consuming crops to conserve water (Wu et al., 2022). Figure 1 demonstrates this argument and idea through visualising Africa’s virtual water imports and exports. Africa imports a total of 2170 Bm3 of water whilst exporting only 80 Bm3 of water. This means that Africa conserves a net volume of 2090 Bm3 of water. 

Focusing on Kenya:

Water scarcity and stress and are serious issues in Kenya that have been existent for decades. Drought conditions over the past two years have been fatal to Kenya’s blue water sites of storage, where 80% to 90% of Kenya’s reservoirs and dams have dried up. This has had knock on effects causing the death of 1.4 million animals and leaving limited irrigation water for agriculture. In situations such as these, residents can only rely on imports of water intensive cereal crops such as barley and wheat, whilst being encouraged to grow less water intensive crops.

Figure 2 – Change in Kenya's production, imports and exports of cereal crops, coffee and tea (Mekonnen and Hoekstra, 2014).

However, Kenya’s economy and livelihood relies on the unsustainable use of water to grow food crops such as maize or coffee which both have large water footprints (Mekonnen and Hoekstra, 2014). Agriculture contributes to 33% of the country’s GDP, with Maize forming 12% of this agricultural GDP and coffee contributing 100 billion Kenyan Shillings or roughly £670 million, to Kenya’s economy from 2001 to 2011. Undoubtedly, these high-value crops form the core of Kenya’s agricultural sector. Nonetheless, these patterns of production cannot be sustained as water scarcity intensifies under drought conditions and climate change. This is the reason why Kenya has shifted to importing over 25% of the country’s cereal products, whilst also increasing exportation of less water intensive crops such as tea and interestingly, cut flowers (Mekonnen and Hoekstra, 2014). Cut flowers, despite using up to 13 litres of water to grow one rose and contributing to pollution in Lake Naivasha, remain important parts of the economy, generating US $353 million in 2005 (Mekonnen et al., 2012). Such a strategy would conserve water for other uses and increase water productivity and cost-efficiency in the long run.  

Whilst Kenya’s strategy and solution sounds economically and environmentally effective, it is important to bear in mind that a heavy reliance on importing food can actually be detrimental for food security at times of crises, such the COVID-19 crisis, where production, trade and logistical systems failed, resulting in panic buying or exacerbated food prices. Moreover, global pressure on fresh water resources will increase, so constantly growing water-intense crops such as wheat or rice becomes unsustainable. Water productivity has to increase to produce large yields of these crops and policies must exist to sustainably manage water resources and their quality (Mekonnen and Hoekstra, 2020). 





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