Scaling of Energy, Water, and Waste Flows in China's Prefecture-Level and Provincial Cities.

Cities have been envisioned as biological organisms as the integral part of nature's energy and material flows. Recent advances in urban scaling research have uncovered systematic changes in socioeconomic rates and infrastructural networks as urban population increases, providing predictive contents for the comparison between cities and organisms. However, it is still unclear how and why larger and smaller cities may differ in their per capita environmental impacts. Here, we study scaling patterns of urban energy, water, and waste flows as well as other relevant measures in Chinese cities. We divide cities into different groups using an algorithm that automatically assigns cities to clusters with distinct scaling patterns. Despite superlinear scaling of urban GDP, as predicted by urban scaling theories, resource consumption, such as the supply of electricity and water, and waste generation, such as wastewater and domestic waste, do not show significant deviations from linear scaling. The lengths of resource pipelines scale linearly in most cases, as opposed to sub-linearity predicted by theory. Furthermore, we show two competing forces underlying the overall observed effects of scale: a higher population density tends to decrease per capita resource consumption and infrastructure provisions, while intensified socioeconomic activities have the opposite effect.

New indices system for quantifying the nexus between economic-social development, natural resources consumption, and environmental pollution in China during 1978-2018.

It is meaningful to study how China can maintain the sustainable utilization of natural resources and the continuous improvement of environmental conditions while ensuring the stable development of the economy and society. In this study, a new indices system was proposed for the analysis of nexus among social-economic-natural resource-environment complex systems following the DPSIR (Driving Force - Pressure - State - Impact - Respond) framework, CCD (Coupling Coordination Degree) analysis and VAR (Vector Auto-Regressive) model were applied for quantifying the synergy and trade-off of China in the nexus framework. Results showed that: (1) Although China's rapid development has caused big consumption of natural resources and increasing pollutants discharges during 1978-2018, China has not got into trouble of extreme resource depletion and ecosystem collapse. On the contrary, China guaranteed food supply, stopped forest degradation, and avoided pollution-induced healthy crises & life-shortening. (2) Adjustment of water pollution industries and the increase of wastewater treatment investment contributed 39% and 37% to the reduction of water pollutant discharge, respectively. The contribution of energy structure adjustment to acid rain control was 26%. The pollutants discharged in no less than 70% of the provinces are strictly controlled below the environmental capacity. The increase of fertilizer application and effective irrigated area contributed 32% to China's grain increase, and China's grain self-sufficiency rate has been maintained above 110%. The improvement of the water-saving irrigation rate contributed 28% to the reduction of water consumption. The reduction of comprehensive efficiency contributed 23.8% to the decrease in energy consumptions per GDP. The CCD assessment showed that China has entered a phase of pre-eminently coordinated development since 2013.