Spatial and Temporal Variation in Water Productivity and Grain Water Utilization Assessment of Heilongjiang Province,Northeast China

Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity (WPg), generalized agricultural water productivity (WPa), evapotranspiration water productivity (WPET) and irrigation water productivity (WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity (WP)indices in the irrigated land of Heilongjiang Province.The results showed that almost all of the municipal WP indices increased from 2007 to 2015.The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET.The spatial patterns of WP indices in different years were similar;the central and southern regions on the Songnen Plain and the eastern region had high WP values,while those of the northern region were low.Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water.Furthermore,the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.