Analysis and prediction of crop water footprints in the Fen River Basin of Shanxi Province, China

In China, the major water user is agriculture. Under the background of climate change and with the pressure of scarce water resources, the study of crop water footprints serves as a theoretical basis for regional optimization of water resource management, fine-tuning crop planting structures and actively addressing the negative impacts of climate change on agricultural production, among other critical issues. Leveraging meteorological and agricultural data, we employed Taiyuan which is situated in Fen River Basin as our focal research subject and calculated and analyzed the water footprint variations concerning six major food crops—wheat, corn, grain, sorghum, soybean, and potato—from 2000 to 2020. Through meticulous examination, we identified the predominant contribution of blue water (45 %) to the total water footprint, followed by green water (39 %), with grey water playing the smallest role (16 %), indicating that the use of water for crops in the Fen River Basin mainly consumes surface water and groundwater. Our investigation reveals a complementary association between blue water and green water, while both blue water and grey water exhibit an overall declining tendency from 2000 to 2020. Moreover, our predictive modeling of food crop water footprints, considering various SSPs-RCPs scenarios refered from IPCC, points towards a peak within the coming 10–20 years, with a growth rate of 16.2 % to 33.0 %, followed by a subsequent decline. Particularly, in SSP3-7.0 scenario, the water footprint of food crops presents the highest, with a growth rate of up to 33.0 % because of the continuous growth of population and the increase of crop sowing area, while in SSP1-2.6 scenario, the water footprint of food crops shows the lowest, with a growth rate of 16.2 % because of the decrease in population and crop sowing area, before the middle of the current century.