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Kimwaga, R.J., Simbarashe, G. & Mtalo, F., (2007). Coping with water scarcity in Eastern Africa: the potential role of intra-regional virtual water trade. Changes in Water Resources Systems: Methodologies to Maintain Water Security and Ensure Integrated Management, (315), p.48. |
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Virtual water is the amount of water required for the production of a
commodity. Trading commodities implies Virtual Water Trade (VWT). This
study was conducted to determine the VWT derived from intra-regional trade
of six cereals (maize, paddy rice, millet, sorghum, wheat and barley) for ten
countries within Eastern Africa from 1998 to 2003. It involved quantifying the
VWT, assessing the role of water scarcity in shaping VWT and determining
the quantity and nature of water savings generated. Quantifying the VWT
included delineating major crop growing zones and calculating Crop Water
Requirement (CWR) using a model, CropWat. Virtual water contents derived
from CWR were multiplied with intra-regional cereal trade flows to obtain the
VWT. Results show that virtual water contents vary significantly within the
region, being higher in the arid countries than the humid countries, partly
because of water scarcity in these countries. Virtual water flows for the region
averaged 150 Mm3
year-1 of water whilst “water savings” averaged 31 Mm3
year-1. Sudan, Uganda and Tanzania are the only net virtual water exporters,
exporting a combined volume of 110 Mm3
year-1, whilst the other seven
countries are net importers, the largest importer being Ethiopia. No correlation
was found between a nation’s water scarcity status and virtual water imports,
suggesting that intra-regional cereal-derived VWT is not a conscious choice
but arises for other reasons like comparative advantage. Sorghum and maize
trade accounted for the largest virtual water flows, 36% and 38%,
respectively, the former due to the high unit virtual water content of the major
exporting countries and the latter due to the large tonnage traded. In a regional
virtual water policy, Kenya, Sudan, Djibouti, Eritrea and Somalia can be
potential virtual water importers, whilst Tanzania, Uganda, Rwanda, Burundi
and Ethiopia can be potential virtual water exporters. It was concluded that
VWT had a big role in water savings in water scarce countries. This has been
considered as a change in water resources systems, and hence maintenance in
water security and insurance in integrated management. |
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