Water and food in Africa

While doing my research about water management and agriculture, I found the TedTalk linked below about the “hidden costs” of our food consumption, increasing my interest about the  virtual water (VW) thematic. This concept, first mentioned by J.A. Allan in 1996, aims to indicate the " conceptual volume of water needed to produce commodities traded to an  importing  country" ( Hanasaki, 2009 ). This term became very popular within the water managem ent literature and was also mentioned by some medias quite early on, with for example the National Geographic publishing a supplement intitled "Hidden Water" in April 2010 . In addition to this, different “kinds” of water can be differentiated when talking about the different elements contributing to the food chain production. For example, with livestock, blue water is used to directly water animals, green water to irrigate the plants then used to feed the betail, and finally grey water, used for the sanitation, cleanin