Impact of spatiotemporal change of cultivated land on food-water relations in China during 1990-2015.

The spatiotemporal change of cultivated land can exert significant effects on food production and the associated water consumption. The quantification of these effects is meaningful for guiding relevant policies. However, few studies have explored systematic methods assessing changes of food production and water consumption and the relations between them, caused by cultivated land change. This study developed new spatially explicit datasets for constant food crop yield and constant food crop water consumption, combining agricultural statistical data, the China-AEZ model, and the GIS spatial analysis method, and estimated the impact of cultivated land change on food crop production, food crop water consumption and food-water relations characterized by two major indicators, i.e., crop water productivity (CWP) and green water proportion (GWP), in China during 1990-2015. The results showed that the increase of approximately 0.80% in cultivated land area in China resulted in a decrease of approximately 0.37% in average food crop yield per unit area, an increase of approximately 1.97% in blue water consumption per unit area (ETblue), and continuous decreases in both total water consumption per unit area (ETa) and green water consumption per unit area (ETgreen), with overall rates of 2.41% and 3.11%, respectively, at the national scale from 1990 to 2015. Concurrently, the average CWP continuously increased with an overall rate of 2.06%, while the average GWP continuously decreased with an overall rate of 0.86% at the national scale. A low-level coupling trend of food-water relations was concluded, together with a negative environmental effect. The food-water relations were getting even worse in major cultivated land expansion areas and during the later period of 2000-2015. The findings of this study can be useful for providing a deep understanding of food-water relations corresponding to cultivated land change and giving suggestions for the sustainable development of cultivated land and the integrated management of water resources.