Actual water consumption index of horticultural and field crops in Iran: Classification into high- and low -water consuming categories

Water scarcity is a critical threat to agricultural sustainability in arid and semi-arid regions. Iran, receiving only 240 mm of annual precipitation on average, faces severe and growing pressure on its water resources, with agriculture accounting for the bulk of freshwater withdrawals. Under such conditions, accurately quantifying the actual water consumption (WRa) of crops is essential for sustainable water resource management and cropping pattern reform. This study calculated and classified the WRa for 83 field and horticulture crops across Iran, using a 10-year national dataset (2013-2023) and a mean WRa threshold of 600 mm to distinguish high water-consuming (HWC) from low water-consuming (LWC) crops. Results showed that 44 crops were classified as HWC and 28 as LWC. Among field crops, sugarcane (Saccharum officinarum; 3,046.8 mm), alfalfa (Medicago sativa; 1,603.9 mm) and Paddy rice (Oryza sativa; 1,249.0) exhibited the highest WRa, while carrot (255.6 mm) and celery (269.5 mm) were the lowest. Among horticulture crops, papaya (Carica papaya; 1,387.6 mm) and date palm (Phoenix dactylifera; 1,286.4 mm) exhibited the highest WRa values, followed by banana (Musa acuminata; 1,217.0 mm) and Sapodilla (Manilkara zapota; 1,132.0 mm), reflecting the exceptional evaporative demand of tropical and subtropical species cultivated in Iran’s arid regions. Although the average WRa of HWC horticulture crops (838.1 mm) was lower than that of HWC field crops (1,086.2 mm), the greater number of HWC horticultural species resulted in a cumulative WRa of 36,877.9 (mm, accounting for 72.3% of the total water use within the HWC category and representing the single largest contributor to agricultural water consumption in Iran. Overall, HWC crops (44 of 83 studied) accounted for 80.3% of total agriculture water use. These findings underscore that reforming horticultural cropping patterns, particularly by restricting tropical and subtropical species with high evaporative demand and promoting low-WRa alternatives, is essential for sustainable water resource management in Iran’s water-stressed agricultural sector.