| Energy and water,as two vital elements driving the socio-economic development,are closely linked to each other,while the existing separated management reduces the effect.As a population and industrial concentration area,urban agglomerations consume lots of energy and water,and their internal cities are experiencing frequent energy-water interactions due to socioeconomic and physical flows.The demand for energy-water collaborative management of urban agglomerations is prominent.Therefore,it is necessary to establish effective methods to characterize the energy-water nexus(EWN)of urban agglomerations,to clarify the inter-city and inter-sector interaction and influence mechanism.Considering the deficient method of EWN analysis at urban agglomeration scales,we proposed a simulation and analysis method based on multiregional input-output(MRIO)for exploring the nexus in urban agglomerations.By combining location quotients with a gravity model,a MRIO table of an urban agglomeration was compiled based on the provincial inputoutput(IO)tables.The IO analysis,ecological network analysis,and other technologies are gradually used to simulate and analyze the EWN.A case study was conducted in the Pearl River Delta(PRD)urban agglomeration.Based on the EWN analysis of "hybrid energy" and "hybrid water",I identified the EWN characteristics of the urban agglomeration,and analyzed the network mechanism of EWN from the aspects of system attributes,ecological hierarchy,and dynamics analysis of the sectors.The main results include:(1)The type of resource acquisition is related to economic development to a certain extent.For example,as the first-tier city,Shenzhen is a typical energy and water predatory city,while Huizhou–a new second-tier city-is not only a typical energy and water self-sufficient city but also an energy-exporting city.In the economic system,the nature of the sector will affect its resource consumption characteristics.Among them,Manufacturing is a typical resourceintensive industry,Transportation is a large energy consumer in densely populated cities,and Agriculture is a water-intensive industry.With respect to supply industries of electricity,steam and gas,Electricity has the highest water intensity.(2)In terms of system attributes,the EWN has improved the Finn’s cycling index of urban agglomerations,but it is still far lower than that of natural systems,reflecting that its energy and water interactions are insufficient,especially in Manufacturing,Production and supply of electricity,steam and gas,as well as Other services.The average mixed energy of urban agglomerations and the robustness of the water system have improved to 0.356 and 0.358,respectively,but the overall situation has not yet reached the state of sustainable development,and the development is extremely uneven,especially in Guangzhou and Shenzhen.(3)The ecological hierarchical structure of the EWN system in the PRD urban agglomeration is relatively unreasonable.Construction has an insufficient driving force,and the driving force is lacking for Production and supply of electricity,steam and gas,as well as Production and supply of water.Manufacturing that plays a major driving role in the energy system and Agriculture that plays a major driving role in the water system needs to further strengthen their driving capabilities.(4)The nexus impact on the control relationship between energy and water systems is mainly concentrated in the internal sectors of the city,but the nexus impact on the dependence relationship is mainly concentrated between the cities.Among them,the control relationship between Construction and Other services of each city has changed significantly,with average values reaching 99% and 60%,respectively.Zhongshan and Zhuhai have the largest changes in energy dependence,and Huizhou has the largest changes in water dependence.Therefore,the collaborative management of urban agglomerations cannot only focus on resource consumption but also need to strengthen the balance between the nexus cycle rate,efficiency and redundancy,the rationality of the ecological structure and the changes in control or dependence.Among them,the optimization of the sectoral structure can effectively save the overall energy and water consumption of the urban agglomeration and improve the sustainability of the system.The simulation and analysis technology for urban agglomerations constructed in this study sets a baseline for EWN studies in urban agglomerations,which can be used as guidance for regional collaborative management. |
