An integrated analysis framework towards identifying circulation relationship of water-energy-carbon in complex system: A case study in Shandong Province

Comprehensive understanding of the complex relationship among water, energy, and carbon emissions (WEC) is crucial for achieving socio-economic structural transformation and regional sustainable development. It represents a complex systemic undertaking that necessitates coordinated efforts across multiple domains and requires intricate planning and balancing. However, as the relationships between regional water resources, energy, and carbon emissions become increasingly acute, systematically examining the circulating relationships of a typical regional Water-Energy-Carbon system under changing conditions is still a challenge for regional sustainable development. In this study, we propose an integrated framework by jointly employing the Environmental Input-Output model and Structural Path analysis to assess the embodied intensities and circulation characteristics of WEC in Shandong Province, a major energy-consuming province in China. The results indicate that in 2017, the industries with the highest embodied WEC intensities are water production and supply industry (224.36 m3/10,000 CNY), coal mining and washing industry (1.66 tce/10,000 CNY), and transportation, postal, and telecommunication industry (2.36 tons/10,000 CNY). During the study period, most industries exhibited decreasing trends in embodied WEC intensities. Notably, the energy intensity and carbon intensity showed a certain positive correlation. For Shandong Province, both the embodied WEC trade flows in 2012 and 2017 demonstrated net inflows. The changes in embodied energy consumption and carbon emissions end consumption were minor, whereas the terminal demand for water resources decreased by 10.3 billion cubic meters, with urban consumption being its main form. Agriculture serves as the largest sector for embodied water transfer and trade-in, while the construction industry is the primary sector for energy and carbon transfer and trade, with 98 % of the construction industry's embodied quantity used for fixed capital formation. This study contributes to bridge the gap in regional resource management and provides a scientific basis to make policy on water conservation, energy efficiency, and emissions reduction.