Spatial-temporal evolution of blue water footprint of crop production and analysis of water-saving potential in the Tarim River Basin

Water scarcity poses a severe threat to food production safety and green agricultural development in the Tarim River Basin (TRB), China. This study evaluates agricultural water-saving potential and cropping structure optimization pathways to support food security and sustainable development in the TRB. Using the blue water footprint assessment method and scenario simulations, we analyzed temporal variations in meteorological conditions and irrigation demands for wheat, maize, cotton, and rice across five prefectures in the TRB from 2000 to 2020. Drip irrigation technology and scenario simulations were combined to identify optimal cropping structures and quantify water conservation potentials. Meteorological parameter-based blue water footprint (WF B ) analysis during the crop growing season (March to October) showed that reference evapotranspiration (ET 0 ) was 62 times that of effective rainfall (P e ). Average temperature (X 1 ) was significantly positively correlated with the WF B ( p < 0.05), and WF B exhibited a generally increasing trend. From 2015 to 2020, the total agricultural land area in the basin increased by 20%. The irrigation demand-based blue water footprint (WF b ) decreased for all crops except cotton. The lowest WF b was achieved under Scenario 6, with a cropping structure of 0% rice, 10% cotton, 30% wheat, and 60% maize, yielding a total water-saving volume of 964.63 million m 3 . When Scenario 6 was combined with full drip irrigation adoption, an additional 7.03% of water could be saved. Compared with the baseline, WF b in Bazhou, Aksu and Kashgar Prefectures decreased by 54.09%, 42.02% and 11.86%, respectively. These findings provide a scientific basis for improving irrigation water use efficiency in the TRB.