Agricultural water use efficiency revisited Focusing on environmental water rights

Agricultural water-use efficiency studies in Iran have mainly focused on a local scale (farm or project) without considering and linking them with basin and global efficiency levels. Moreover، it is indicated that the classical concept of physical water- use efficiency is concerned with local and ignores the potential for return flows and recycling. Hence، the findings of these studies are not appropriate for policy recommendations about water allocation at the basin or global levels. Due to continuous and integrated nature of hydrological cycle، it is essential to consider the whole cycle in addressing water- use and water application technology problems. This study moves beyond the traditional practice of analyzing the agricultural water- use efficiency by considering and linking together three levels: local، basin and global، including the possibility of virtual water import and export and their environmental impact. In conclusion، based on some studies elsewhere and field observation in Iran، some caveats and limitations in choosing water-saving irrigation technology and methodology used were indicated.