Improving the resource utilization efficiency in irrigation systems contributes to the sustainability of the regional water-energy-grain nexus. Based on the water, energy and grain relationships quantification, the comprehensive efficiency (CE) of water transfer and grain production processes and its driving mechanism were analyzed, considering a pumping irrigation system in the Lianshui irrigation district (LID) in eastern China, as a case study. The annual crop output, crop water footprint, and electric energy consumption were estimated as 905.3 M kg (1 M = 106), 914.7 M m3 (50.7% blue water), and 3004.0 kWh, respectively, from 2005 to 2018; the corresponding crop water productivity (CWP), electricity energy productivity (EEP), water intake efficiency of electric energy (WIE) were 0.91 kg/m3, 80.39 kg/kJ, and 75.22 m3/kJ, respectively. CWP, EEP, and WIE varied among crops; however, none of the three indicators showed an obvious trend of change with time. The CE of integrated grain was 0.48 and showed an increase over time, indicating that the sustainability of the studied pumping irrigation system was improving. The driving effect of artificial factors (e. g. social development, agricultural input, and water management) on the CE was more obvious than that of natural conditions (e. g. climate). Increasing agricultural machinery and urbanization rates and reducing the agricultural water rate are conducive to improving the resource utilization efficiency in pumping irrigation systems. The analysis framework coupling water footprint and traditional paradigms proposed in this paper provides a feasible approach for the stability and sustainability of irrigated agricultural systems observation.
Keywords: Blue-green water; Driving factor; Efficiency indicators; Pumping irrigation; Water-energy-grain.
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