Analysis on temporal and spatial differences of water productivity in irrigation districts in China

Based on grain output and generalized water resources input, water productivity and utilization factor of generalized water in irrigation districts of 31 provinces were counted and it's spatial and temporal differences were analyzed. The results showed that water productivity of every province presented an increasing trend, and national average water productivity increased from 0.67 kg/m3 to 0.81 kg/m3from 1998 to 2010. Spatial autocorrelation analysis results showed provinces with resemble water productivity value showed significant aggregation, and Moran's I inspection values were higher than confidence level (0.01). Distributions of provinces with high water productivity value were centered with Huang-Huai-Hai plain, and provinces with lower water productivity values were distributed in South and Northeast China. Local autocorrelation analysis revealed that more than 20 provinces showed high-high positive autocorrelation(HH) and low-low positive autocorrelation(LL), general and regional spatial differentiation characteristics in 1998-2010 was insignificant. Generalized water use coefficient of different province increased, and there were no consistency on relations between water productivity and water use coefficient in different provinces, there were still great water saving potential in provinces with high water productivity value, and reasons of spatial differences for water productivity and generalized water utilization factor were analyzed from natural conditions, agricultural production features, economic development levels, etc. This research provides references for making macro policies of water resources management in irrigation districts.