Water footprint and stress index assessment in Mediterranean agriculture

Water scarcity remains a significant challenge to agricultural sustainability in semi-arid and Mediterranean regions, with Kermanshah Province, Iran, exemplifying this issue. This study evaluates water resource dependency and water stress in Kermanshah's agricultural sector from 2010 to 2019, using comprehensive water footprint indicators, including the Water Stress Index (WSI), Agricultural Water Stress Index (AWSI), Blue Water Scarcity Index (BWS), and Regional Agricultural Water Footprint Intensity (AWFI). Plant-related data, such as evapotranspiration, effective rainfall, crop water requirements, and irrigation needs, were estimated using NETWAT (Network for Water and Agriculture Technologies) software alongside the FAO-Penman-Monteith (Food and Agriculture Organization)-Penman-Monteith equation. The results reveal that producing 26.62 million tons of crops (field and orchard crops) required a total water footprint of 159.8 Gm³, with field crops contributing over 90% of the total. Blue water, representing surface and groundwater resources, was the largest component (71.99%), followed by green water (16.86%) and gray water (11.14%). Among orchard crops, walnuts exhibited the highest total water footprint (4,079.75 m³/ton) under irrigated conditions, while, grapes had a total water footprint of 626.63 m³/ton. For field crops, chickpeas demonstrated a high-water footprint due to irrigation demand and fertilizer use, with a total of 4,646 m³/ton. Water stress indices showed persistent resource pressure. The BWS index exceeded 0.8 in all years, peaking at 0.93 in 2016, while the AWSI peaked at 0.87 in 2013, highlighting severe agricultural water scarcity. Water deprivation reached a maximum of 8,380 MCM in 2014, driven by low rainfall and overextraction of water resources. Although precipitation improvements in 2018-2019 slightly alleviated pressure, increased agricultural demand prevented significant recovery. The findings underscore the urgent need for sustainable water management strategies, including advanced irrigation technologies, optimized fertilizer application, and cultivation of high-yield, water-efficient crops.