Water Security, Food Security and the National Water Dependency

Abstract

Water requirements for food demand in Tunisia have more than tripled over the past four decades, and amount to more than 16 km³ in 2010. As the population has nearly doubled during the same period, water requirements for individual dietary recorded an increase from about 1050 m³/year/capita in the early 1970s to nearly 1600 m³/year/capita in the late 2010s. To draw up an outlook of water-balance future, long term perspectives for all kinds of water resources are carried out with various demographic hypothesis. The blue water evolution relies on substantial increase of non conventional water and stronger water uses control. The blue water footprint of crop productions will rise from 1.4 km³ in 2010 to 2.1 km³ by 2050. At the same time, green water involved in food production is expected to increase by almost 25%. With the medium variant of demographic projection, the water balance deficit would be around 13 km³ in 2100 and the water dependency index, ratio of imported virtual water minus the exported one divided by the water equivalent of the food consumption, will increase from 39% in 2010 to 48% in 2100. With higher population hypotheses, the water dependency index could reach 62%, and perhaps even more under the global warming effect.