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In China, over 65% of human activities are concentrated in cities, resulting in a conflict between the supply and demand of ecosystem services (ESs). To alleviate this problem, many cities have adopted eco-friendly development modes, however, the effectiveness of these models in reducing ESs supply-demand conflicts has not been comprehensively reviewed, and the human and natural drivers behind these relationship shifts remain unclear. To bridge this gap, this study analyzed the shifts in the relationships between supply and demand of ESs across China from 2010 to 2020 at a city level, as well as identified the human and natural drivers behind them. Firstly, the InVEST models were integrated with socioeconomic data to evaluate the supply and demand distribution for three pivotal ESs: water yield (WY), habitat quality (HQ), and soil retention (SR). Then, a four-quadrant diagram approach was proposed to enhance the analysis of their spatiotemporal relationships. Furthermore, random forest models were employed to examine the drivers of the shifts in these relationships. The results showed that WY and SR services witnessed growth until 2015, and then receded, while HQ saw a modest decline from 2010 to 2020. Spatial synergies in the supply and demand of ESs were primarily observed in the southern cities, with a significant northward extension by 2020. From a temporal perspective, the percentage of cities achieving coordination in WY and SR services increased from 32.6% to 57.3%, respectively, in the 2010–2015 period to 42.4% and 63.3% between 2015 and 2020, meanwhile, HQ service conflicts diminished from 58.7% to 53.5%. The changes in socioeconomic and land use factors contributed to 64.3%, 36.1%, and 33.3% of the shifts in the supply-demand relationship for HQ, WY, and SR services, respectively. Our analysis highlights the potential of human-driven ecological management to enhance the balance of this relationship. It can support the design of city-specific policies that foster a balance between ecological processes and socio-economic development. • The supply and demand of three critical ecosystem services were evaluated. • The spatiotemporal supply-demand relationships of ecosystem services were identified. • The natural and human drivers of these relationship shifts were examined. [ABSTRACT FROM AUTHOR]

The ecological restoration of river basin is sensitive to ecosystem service variation. However, previous ecological restoration effectiveness assessments often ignore the social perception of ecosystem services. This paper proposed an integrated effectiveness assessment framework for ecological restoration incorporating public satisfaction level. The InVEST model was deployed to compute four key ecosystem services, which are water conservation, water purification, soil retention, and carbon storage, by using both market price and in-lieu cost methods. Then, public satisfaction as incorporated into cultural services was quantified via social media analytics using the travel cost method. Taking the Yongding River as a case, we analyzed its pre- and post-ecological restoration performance during 2015–2021 using the proposed framework. The results showed that the ecosystem service value surged by $2664.19 million, resulting in an ecosystem service change index (ESCI) of 24.49%. In particular, a 20.27% increase in the public satisfaction level was found. Public satisfaction contributed 39.25% to the total increase in the ecosystem service value of the Yongding River. Our study may provide support for ecological restoration strategies concerning both physical and public demand aspects. [Display omitted] • An integrated assessment for ecological restoration effectiveness was developed. • Social Media Analytics was used to quantify the cultural services. • The public satisfaction contributed 39.25% to the total increase of the Ecosystem Service Value of the Yongding River. [ABSTRACT FROM AUTHOR]

Tracking China's national and regional CO2 emission trends is becoming ever more crucial. The country recently pledged to achieve ambitious emissions reduction targets, however, high-resolution datasets for provincial level CO2 emissions in China are still lacking. This study provides daily CO2 emission datasets for China's 31 provinces, including for the first time, the province of Tibet. The inventory covers the emissions from three industrial sectors (power, industry and ground transport) during 2019 to 2020, with its temporal resolution at a daily level. In addition, the variations in CO2 emissions for seasonal, weekly and holiday periods have been uncovered at a provincial level for the first time. This new data was added to further analyze the impact that weekends and holidays have on China's CO2 emissions. Over weekend periods, carbon emissions are shown to reduce by around 3%. Spring Festival meanwhile, has the greatest impact on the reduction of China's CO2 emissions. This detailed and time-related inventory will facilitate a more local and adaptive management of China’s CO2 emissions during both the COVID-19 pandemic’s recovery and the ongoing energy transition. The data are archived at https://doi.org/10.5281/zenodo.4730175 (Cui et al., 2021). [ABSTRACT FROM AUTHOR]

Wastewater treatment plants (WWTPs) play a pivotal role in natural water recycling and safeguarding the water security of approximately 42% of the world's population, yet they confront challenges posed by escalating energy consumption and regional energy constraints. In this study, we developed an evaluation framework that integrated regional energy scarcity with the operation conditions of WWTPs to quantify their energy efficiencies by applying multiregional input–output (MRIO) analysis and data envelopment analysis (DEA). A case study using this framework was conducted on 3776 WWTPs in 30 provinces in China. The results showed that the average scarcity-based energy efficiency level of WWTPs in China was low, of which those in northern provinces were higher compared to southeastern provinces. Furthermore, only 24 WWTPs in China attained the highest efficiency levels, while the rest had different degrees of input redundancy, indicating an energy-saving potential of 9.05 × 109 kWh. This paper enables the development of optimal efficiency strategies for WWTPs in different provinces considering the potential energy scarcity risks caused by trading activities. • The DEA and MRIO analyses were combined for 3776 WWTPs in China. • Efficiency evaluation index was modified considering energy scarcity levels. • Scarcity-based energy efficiency assessment framework for WWTPs was developed. [ABSTRACT FROM AUTHOR]

Highlights • The input–output model and ecological network analysis (ENA) are integrated. • The control and dependence conditions of economic sectors in China are analyzed. • The key regions and sectors for carbon mitigation of China are identified. Abstract In this paper, multi-regional input–output analysis (MRIO) and ecological network analysis (ENA) are combined to assess carbon flows within China and identify key regions and sectors in the context of spatial heterogeneity for effective carbon mitigation. An interregional carbon network model is established by articulating the directions and magnitudes of carbon flows based on MRIO. ENA is then used to unveil indirect carbon flows and mutual relationships among regions. The results show that the northwest is the largest controller for most regions in China. Most carbon emissions in the rest of China are induced by the east’s final demand and substantial consumption. In addition, at sectoral level, the control and dependence abilities vary by region in China. This study provides an integrated framework to investigate interregional carbon emission structure, identify efficient pathways for coordinated emission mitigation, and reduce global carbon inequality across regions. [ABSTRACT FROM AUTHOR]

There is a large amount of water consumption embodied in energy production. Driven by a growing population and economy, the energy sector will continue to expand, increasing more pressure on the fresh water demand of countries. This paper analyzes the energy–water nexus embodied in international energy trade via a combination of input–output analysis (IOA) and ecological network analysis (ENA). The energy–water element nexus is depicted based on a mixed-unit IOA to investigate the parallel relationship between energy and water. ENA is used to uncover energy–water pathways intertwined in global energy trade and identify the pair-wise relationship between countries according to the energy–water pathway nexus. Then, a case study of the international energy–water nexus of China is conducted. The results of energy–water nexus element analysis show that water use per unit of energy products in the country is much greater than those of other countries. Moreover, indirect water use during energy production deserves more attention, which is often neglected in water resource management. The results of energy–water nexus pathway analysis demonstrate that international energy trade has a positive effect on China’s water condition, mitigating serious water shortage problems but increasing dependency on other countries and regions. Mutual relationships among trading countries are described using utility and control analyses. The results show that system integrality is arguably more critical in determining system behavior than direct effects alone. Europe changes from a beneficiary in direct mutual relationships to a contributor in integral utility mutual relationships, whereas Australia has an opposite change. Although China has a dominant position in direct relationships, it becomes an equal competitor with the USA in utility mutual relationships. China depends heavily on most countries, especially those in South and Central America, the Middle East, Africa, and Australia. The network mutualism index (=0.56) and synergism index (=9.187) indicate that the current global energy trade network has negative relationships within a competitive environment. Finally, policy and economic suggestions are put forward to alleviate the potential impacts of international energy trade on water scarcity in China. [ABSTRACT FROM AUTHOR]

The heterogeneity of water and energy resource endowments and increasingly closer trade links among regions make it challenging to attain synergy in energy conservation and main pollutant reduction. This paper quantified the provincial energy intensity of COD removal in wastewater treatment plants (WWTPs), tracked the sectoral and regional water pollutant (COD) transfers beneath the provincial economic transactions based on the multi-regional input-output analysis, and evaluated the energy saving and loss in different provinces based on an energy-pollutant nexus assessment framework. We found that economic trade could transfer local pollutant reduction pressure to distant regions through the national economic system. The critical VCOD importers (Beijing and Zhejiang) and exporters (Jiangxi and Heilongjiang) highlighted the necessity of emission reduction responsibility assignment from both the demand and the supply side. The VCOD was transferred from higher energy intensity provinces to lower energy intensity provinces, which contributed to a 1.42 × 108 kWh energy loss of COD removal nationally. Our results showed that from the energy-pollutant nexus perspective, some of the energy conservation and pollutant reduction goals were not always consistent. This study may help optimize the spatial regulation of national energy conservation and pollution reduction in a more integrated and systematic way. [ABSTRACT FROM AUTHOR]

• The connection lengths of trade linkages between regions and sectors are evaluated in an input–output framework. • The combination of the size of the linkages and the distance between sectors can visualize the production structure. • The responsibility, role and position of sectors and regions are quantified in context of CO 2 emissions and added-values. It is crucial to investigate the roles and positions of various nodes along the whole production chain regarding carbon emission mitigation for rational and equitable decarbonization policies. This study probes into the coupling mechanism between carbon emissions and added values among different sectors of 30 regions in China with average propagation length analysis. Average propagation length index is employed to evaluate the connection length of trade linkages between regions and sectors within input–output framework in the production chain. The results reflect the unbalance of industrial chain's value distributions and the carbon emission distributions as well. From regional perspective, the developed regions like Beijing and Shanghai outsource the carbon emissions embodied in primary products via the production chain, while such carbon-intensive products generating in surround regions achieve lower portion of added value gains. Along the whole production chains, most of the added value benefits are obtained from the trade, finance, and real estate sectors in developed regions, which hardly generate carbon emissions. From sectoral view, the sectors like construction and real estate industry have specific roles in context of the whole production chains, whose upper production streams are complex and correlated with carbon-intensive sectors like metal, nonmetal, and equipment production. It can be concluded that the combination of the size of the linkages and the distance between sectors may visualize the added value and emission structure between each sector and region along the production chains. [ABSTRACT FROM AUTHOR]

• Structural decomposition analysis is used to investigate the water-energy nexus. • Energy intensity is the most important contributor of water-energy nexus. • The production structure change has significant indirectly effects on water flows. Water and energy are intertwined during their production and consumption processes. Static assessments and simulations of the water-energy nexus among production and consumption are important for determining the mechanism behind the nexus; however, dynamic studies can help determine the most important factors that influence the development of the water-energy nexus, which can provide new insights for shaping energy and water synergetic management. Thus, we probed the driving factors of the water-energy nexus in China through structural decomposition analysis from 1990 to 2014 and decomposed the water consumption of different consumers into six energy related factors: the water-energy nexus coefficient, the energy intensity, the production structure, the consumption volume per capita of final consumers, consumption patterns, and the population. The results showed that the consumption volume, which indicates the consumption levels of different consumers, contributed 156% of the increase of the total energy related water consumption in 2014 compared with that in 1990. Additionally, the energy intensity is the most important driving factor that can reduce the total water consumption of all consumers (household, government, gross fixed capital format, etc.), accounting for −271% of the water consumption in 2014. The consumption patterns, i.e., expenditures on various products in different sectors, also show positive impacts on water consumption conservation for the gross fixed capital format and government, although they can aggravate the water consumption in households. The investigation of the driving forces for different consumers also shows that prosperity in the real estate industry and other related industries has indirectly driven more water flow into gross fixed capital investments and the government, which negatively affects the sustainable water consumption goal in China. [ABSTRACT FROM AUTHOR]

China's energy transformation has been accompanied by potential energy security issues. However, the influence degree and driving mechanism behind this phenomenon remain unclear. In this paper, we developed a complex network-based technical resilience assessment framework and quantified both the historical trajectory and the prospective pathway of energy technical resilience in China. We proposed to reveal the relationship between cleaner energy supply and technical resilience by defining three energy technology resilience indicators: energy robustness, energy recovery rate, and energy performance loss. The results showed a consistent decline in energy technical resilience within China, predominantly characterized by an average diminution of 6.83% in energy robustness from 2010 to 2018. Taking carbon neutrality as a target, China's energy system transformation, characterized by increasing clean energy supply, leads to a significant improvement of 7.73% in energy robustness from 2020 to 2060. Conversely, the nationally determined contribution scenario exhibited negligible changes (±0.57%) in energy robustness, while a decline of 2.21% was noted under the business as usual scenario. Furthermore, energy robustness exhibited increments of 12.07%, 2.3%, and 4.17% for every 10% rise in the share of clean energy supply during 2020–2060, demonstrating greater resilience for cleaner energy systems against disruptions, including energy import interruptions, malicious attacks, and random failures. It has been concluded that enhancing the supply of clean energy can significantly contribute to bolstering China's energy technical resilience, while simultaneously addressing climate change concerns. • Network analysis is used to assess China's energy technical resilience. • Energy technical resilience is evaluated regarding robustness, recovery rate, and performance loss. • Energy system robustness significantly increases under carbon neutrality scenario. • Increasing clean energy supply strengthens resilience against shocks. [ABSTRACT FROM AUTHOR]

There is unequal spatial distribution of resource endowment, population density, industrial structure, and economic development with diverse differences in labor, energy, and capital productivities in China. However, previous studies paid little attention to the determinants of CO 2 transfers embodied in electricity trade. In this study, we use both the absolute and comparative advantage theories to reveal the determinants of embodied CO 2 transfers through electricity trade within China. Results show that China's electricity sector has higher labor productivity but lower asset efficiency and energy productivity than that of mining and manufacturing sectors. The large-scale electricity trade alleviates the shortage of electricity supply in developed regions by outsourcing to the less-developed regions, reduces the unequal spatial distribution of coal and natural gas reserves, and changes CO 2 flow embodied in power grid. Econometric analysis shows that coal reserve contributes to the increase of embodied CO 2 emission, while natural gas reduces the embodied CO 2 emission. The regional differences in the opportunity cost of labor productivity of non-electricity sector are the dominant factor of the embodied CO 2 transfers through electricity trade within China, while asset efficiency and energy productivity are not significant in the regressions. Our findings could provide details about China's power grid expansion when confronting climate mitigation in the future. • Absolute and comparative advantage theories in determining the embodied CO 2 transfers through electricity trade. • Electricity sector has higher labor productivity but lower asset efficiency and energy productivity than other sectors. • The electricity trade alleviates the shortage of electricity supply in developed regions by outsourcing. • Coal reserve increases the embodied CO 2 emission, while natural gas reduces the embodied CO 2 emission. • The opportunity cost of labor productivity of non-electricity sector is the dominant factor in the embodied CO 2 transfers. [ABSTRACT FROM AUTHOR]

• A segmentation framework combining rule-based simulation and optimization is proposed. • The method of identifying segmentation points based on rule-based simulation is applied. • The optimization time can be effectively reduced by segmented optimization method. With the urban water resources becoming increasingly scarce, the optimal control engineering has emerged as a promising approach to improve the efficiency of water use in the environment. A hydraulic model is capable of accurately modeling and predicting the complex hydrodynamic processes occurring within a channel. However, its optimization and simulation time are often prolonged by the complexity of the channel system, resulting in poor real-time performance. This study presents a segmented hydraulic real-time optimization approach that combines rule-based simulation (RS) with real-time optimization (RTO). The aim of the proposed method is to reduce hydraulic model complexity and improve optimization time by dividing the full hydraulic model (FHM) into optimized segmented hydraulic model (SHM O) and non-optimized segmented hydraulic model (SHM N). The approach presents two main improvements: (1) a segmentation point recognition method based on RS is used to obtain SHM O from the FHM; and (2) a segmented optimization framework is employed to enable RTO based on SHM O. We demonstrate the effectiveness of the approach using a case study of China's Qing River. The results indicate that FHM can be successfully divided into SHM O and SHM N with similar simulation effect (R > 0.88 and RMSE < 0.1) by using the segmentation point recognition method, and the segmented hydraulic real-time optimization approach can reduce optimization time (average 68%) of hydraulics model. The case study indicated that the proposed method is a computationally efficient and feasible approach for real-time regulation of urban channel gate control based on hydraulic model. [ABSTRACT FROM AUTHOR]