Generalized water efficiency and strategic implications for food security and water management: a case study of grain production in China

An index, generalized water efficiency (E_g), for the effective utilization rate of blue-green water evaluation was established in this paper. E_g in grain production for 31 provinces of China during 1998-2010 were calculated. Then temporal-spatial patterns and attribution analysis of E_g in China were explored and conducted by using spatial autocorrelation and path analysis methods, respectively. The results show that, national value of E_g was estimated to be 0.588 in 1998-2010 and the index increased slightly in most of the provinces. Spatial autocorrelation analysis results shows, provinces with resemble E_g value shown significant aggregation. Regions with high E_g values are gathered in Western China while ones with lower E_g distributed in Southeast China; and the global and local spatial aggregation showed decreasing trends over time. E_g was affected strongly by regional agricultural production management level, while the climate and economic conditions had less influence on the effective rate of blue-green water resources. Making a general survey of provincial E_g, water productivity (P_w), water stress index (WSI) and grain production ability, southwest provinces may expand grain production scale in order to play the advantage of high E_g, and major grain producing areas of Northeast China should take measures to raise E_g to ensure food security and sustainable utilization of water resources. The results of this report can provide reference for the development of national water efficiency in agriculture and food production and water resources management strategy.