Water footprint assessment of main cereals in Iran

Iran is mostly located in arid and semiarid regions which makes agricultural water management considerably important in this country. In this research the concept of 'water footprint' (WF) is applied at the regional scale for the first time in the country. The calculation framework of Ababaei and Ramezani Etedali (2014) was adopted and modified to better account for the gray and white WFs. The weighted average of each WF component (green, blue, gray and white) and the national total water footprint (NTWF) of the production of main cereals (wheat, barley and maize) were calculated. The NTWF of wheat, barley and maize production were estimated 36,777, 7975 and 3744 million cubic meters (MCM) per year for the period 2006-2012. The ratio of total green WF of three crops to the aggregated NTWF (i.e. all crops) was 43%, and the ratios of the green WF to the NTWF were 47%, 42% and 2% for wheat, barley and maize, respectively. These results show that wheat and barley production are significantly large consumers of the green water resources (i.e. effective precipitation). This implied that there are great opportunities to improve the green water productivity through increasing yield, especially in wheat and barley rainfed lands. The average national green+blue WFs were estimated 24,628, 5,123 and 1,604 MCM per year for wheat, barley and maize, respectively, and 31,356 MCM per year altogether. The ratios of national gray + white WF to the NTWF were also estimated 33%, 36% and 57% for wheat, barley and maize, respectively. These values show the importance of better irrigation management strategies to reduce the share of gray and white WF which is important in both terms of water resources management and environment conservation.