Consumption of cropland with high yield and low irrigation water intensity by urban expansion in China during 2000-2015

摘要

Cropland is fundamental for food production, which consumes a considerable amount of fresh water in the production process. Cropland with a high yield and low water intensity is extremely precious for realizing the sustainable and environmentally friendly utilization of cropland. However, urban expansion often occurs on cropland, and there is not enough scientific understanding of the features of cropland lost by urban expansion. Here, combining land use data, agricultural statistical data, the China-AEZ model and the GIS spatial analysis method, a spatially explicit constant food crop yield and "colorful" water intensity datasets were developed and preference indices were estimated, aiming to identify the features of cropland lost by urban expansion in China. The results showed that urban expansion played an increasingly dominant role in cropland loss in China during 2000-2015, with the area of cropland lost by urban expansion accounting for 63.48% of the total area of cropland loss. Urban expansion preferred to consume cropland with high yield and cropland with low blue water intensity (BWI), and the corresponding preference indices equaled 1.57 and 1.33, respectively. In addition, a coupling index was introduced to estimate the coupling relationship between the food crop yield and BWI of cropland, and the preference index of high-coupling-index cropland lost by urban expansion was 1.61 during 2000-2015, indicating that urban expansion was preferentially occurring on cropland that was both high-yield and low-BWI. In terms of the temporal and spatial variations, the degree of preference for cropland of high yield and/or low BWI lost by urban expansion all increased slightly at the national scale, while the preferences were more centralized in three southern regions, including the middle and lower reaches of the Yangtze River (YRR), southeastern China (SER), and southwestern China (SWR). In contrast, there were no such preferences in other regions. The preference of urban expansion consuming cropland with low total water intensity and green water intensity was also not significant at the national scale during 2000-2015.