Input-output efficiency evaluation of regional water-energy-food nexus under relational network and uncertainty

Complex interrelationships and parameter uncertainties make it difficult to accurately assess the input-output efficiency of Water-Energy-Food (WEF) nexus. In this study, a fuzzy relational network data envelopment analysis model is developed. This approach is capable of describing the complex interrelationships between subsystems in fuzzy environments. For illustration purpose, this approach is applied to measure the performances of WEF nexus in Guangdong Province, China. Results indicate that the Pearl River Delta has higher WEF efficiency because of the coordinated development of subsystem efficiencies, while the other regions have lower WEF efficiency owing to the low efficiency of a certain subsystem. The WEF system has experienced three stages of decline, fluctuation and growth, with 2010 and 2015 as the turning points. The efficiency of water and energy subsystems are the main driving factors of the time variation of WEF nexus efficiency. Of all the intermediate products, the energy consumption for water supply needs to be increased the most, and agricultural water use needs to be reduced. Comparison against alternative models shows that the proposed model provides an efficient way to describe inter-subsystem linking activities and to process fuzzy information. Sensitivity analysis shows that the proposed model is robust when faced with reduced input indicators. The proposed approach is also potentially applicable to evaluating the efficiency of other systems with complex internal correlations under uncertainty.