The extended water footprint of the Guadalquivir basin
ABSTRACT: This chapter analyzes the Extended Water Footprint (EWF) of the Guadalquivir basin in south of Spain. An innovative aspect is that not only the use of blue water for direct human use (irrigation, urban and industrial supply) has been taken into account but also the use of green water for the mentioned uses and the natural ecosystems; the latter amounts to 291 mm/year. The results show that agriculture is the main consumer (192 mm/year), 34% being blue water and 66% green water. Economic productivity fluctuates between less than 0.40 €/m3 for the most traditional crops (cereals, maize, cotton and rice) and values reaching 2 €/m3 for olives and more than 4 €/m3 for vegetables. But the highest economic productivity is tourism (more than 200 €/m3) and industries such as thermo-solar energy (50 €/m3). A better water management could be achieved thanks to a reallocation of water resources between the different uses. This reallocation may occur without social conflict with the farmers since the quantities of blue water required constitute 1-2% of the current total blue water use. However, this process is much more complex since a large number of economic, social, political and environmental factors need to be considered.