Spatio-temporal analysis of irrigation water use coefficients in China.

Water shortage is a major problem for agriculture in many countries. Agricultural water accounts for more than 60% of total water consumption in China. Improving agricultural strategies in using irrigation water more effectively and efficiently is important to alleviate water shortages and associated environmental problems. In this study, the spatiotemporal distribution differences of irrigation water use coefficient in large, medium and small-scale irrigation districts and pure well irrigation districts in the 31 provinces of China (excluding Hong Kong, Macao and Taiwan) were analyzed by means such as the Zipf's law and spatial autocorrelation. The results showed that the national irrigation water use coefficient had increased from 0.501 in 2010 to 0.542 in 2016. By size of irrigation area, the irrigation water use coefficient in small irrigation areas was higher than that of large- and medium-scale irrigation districts. Regionally, the irrigation water use coefficient in the eastern region was significantly higher than that in the western region, and the coefficient in northern region was higher than that in the southern region. The spatial spillover effect of the national irrigation water use coefficient gradually weakened, and the spatial spillover effect of large and medium-scale irrigation districts was not obvious. The spatial spillover effect of pure well irrigation districts varied greatly over time. All these results give a spatiotemporal overview of agricultural water use in China, which provides a direction for improving irrigation water coefficient in China.