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The spatial mismatch between energy resources and water resources has been widely concerned. Electricity trade drives virtual water flows from electricity production sides to consumption sides, which can aggravate or alleviate regional water scarcity. Investigating the historical evolution of virtual water transmission and its impacts on water scarcity benefits the sustainable development of energy and water. To reduce data uncertainties, in this study, we built provincial water intensity of electricity generation inventory considering the impacts of factors such as electricity generation types, cooling technologies and generator units. Besides, to investigate how the direction and quantity of virtual water flows aggravate or alleviate the regional water scarcity, the impact assessment model was built, and the impact assessment index was defined. The results showed that the water consumption of electricity generation and interprovincial virtual water transfer increased by 2.61 times and 5.12 times during 2005–2015, respectively. Changes in the amount of electricity generation and the electricity transmission structure were the two main drivers of increases in virtual water flows, contributing to a total increase of 85.28%. A large amount of virtual water was transferred from the southwest and the northwest to the eastern coastal areas. There were many "positive flows" from the southwest to Jiangsu-Zhejiang-Shanghai, while "negative flows" were concentrated in Xinjiang-Henan, Gansu-Qinghai and Gan-Shaanxi. The nodes with the largest impact assessment index value were Hubei, Sichuan and Shanghai, while the lowest were Gansu, Xinjiang and Qinghai. This study can provide a basis for optimizing the electricity generation mix and electricity transmission structure, alleviating the growing tension between energy and water, and realizing the sustainable development of water resources. • The provincial water intensity for electricity generation inventory is built. • The amount of virtual water flows increased 5.12 times from 2005 to 2014. • The virtual outflows of the southwestern regions alleviated national water scarcity. [ABSTRACT FROM AUTHOR]

• A multi-objective optimization model is established for electric power sector. • Water consumption and carbon emissions from power generation are quantified. • Tradeoffs between water and carbon in electricity mix are evaluated. • Strategies for optimizing electricity mix and tasks distribution are proposed. Electric power sector is a significant water consumer and a major source of carbon emissions in China. Optimizing electricity mix is critical for maintaining a stable energy supply while addressing water stress and carbon emissions associated with power generation. In this study, we developed an optimization model with the dual objectives of mitigating the risk of water scarcity and cutting carbon emissions, by adjusting the electricity mix and power generation tasks of provincial grids. Using the weighted sum method, the optimization of grids is simulated based on a scenario analysis within specified equality and boundary constraints. We quantified the impact of the spatial distribution of thermal power and power generated from clean energies (hydropower, wind power, nuclear power, and solar power) on virtual water consumption and carbon emissions at a provincial level in China. The results suggested that transferring part of power generation tasks from water-deficient areas (e.g., Shandong and Jiangsu) to water-sufficient areas (e.g., Yunnan and Guangdong) could significantly mitigate water scarcity. Water consumption of power generation could be reduced by 34.7% in highly water-deficient areas if a water-prioritized scenario is implemented. Carbon emissions related to power generation could be reduced nationwide under a carbon-prioritized scenario and a water-carbon-balanced scenario. This model could provide a synergistic perspective for improving regional water and carbon performances based on changes in electricity mix. [ABSTRACT FROM AUTHOR]