The notion of water footprint provides a novel perspective for understanding the relationship between physical water and virtual water, especially in agricultural production. In this study, with the help of CROPWAT 8.0 model, we estimate the water footprint requirement (WFr) of main crops growth for 2005, 2010 and 2015 in Zhangjiakou City, an extreme water shortage region in northern China, and three new indicators are introduced, i.e., green water footprint occupancy rate (GWFor), blue water footprint deficit (BWFd), and virtual water consumption per output value (VWV). The results indicate that the total WFr increased from 1.671 billion m3 to 1.852 billion m3 during the study period, of which the green water was always about twice as the blue water. Cereals, as the main staple food, had the largest WFr, while the WFr of potatoes increased the fastest, which was the result of large-scale promotion of potato cultivation in recent years. The spatial characteristics of the GWFor and BWFd are closely related to altitude, that is, the GWFor was less than 50% in higher-altitude Bashang area, while it was more than 50% in lower-altitude Baxia area, and the BWFd was generally smaller in Bashang area than in Baxia area. Due to differences in crop types and food prices, higher water footprint food productivity does not absolutely mean higher water footprint economic productivity. Therefore, it is vital to consider from two perspectives (food yields priority or economic benefits priority) to formulate a reasonable water footprint utilization policy. This study is expected to broaden the investigation of crop water footprint and make a contribution to sustainable agricultural water management.
Keywords: Blue water deficit; Crop water footprint; Economic benefits; Green water occupancy rate; Zhangjiakou City.
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