System nexus consolidates coupling of regional water and energy efficiencies

Pursuing synergetic improvement of efficiencies of water and energy utilization facilitates joint resource management given the water-energy nexus. The coupling between regional total factor water efficiency (TFWE) and total factor energy efficiency (TFEE) remains to be explored especially considering complete water-energy nexus. We construct an integrated water-energy framework with intensified system nexus, and combine super efficiency slack-based measure model and coupling coordination model to evaluate the coupling between TFWE and TFEE in 30 Chinese provincial regions. Results indicate that regions have better performance on TFEE than TFWE (0.69 > 0.63). The interaction between TFWE and TFEE maintains an excellent level, with the coupling level greater than 0.95 for all regions, while the coordination level differs largely across regions. For the comprehensive coupling level, all regions are at middle coordination coupling level and above, and spatially the eastern economically leading regions (Beijing, Shanghai, Guangdong, Shandong, Jiangsu, etc.) are more advantageous than the inland ones. The identified more influential inputs and outputs reveal pathways to improve TFWE and TFEE, and the coupling in between. This study provides a new perspective for studying water-energy nexus and a support for decision-making on synergetic water-energy management considering local conditions. (c) 2022 Elsevier Ltd. All rights reserved.