High-Resolution Mapping of Carbon Flows in Urban Systems: A Case Study in Guangyuan, an Earthquake-Affected Mountainous City of China

Being different from inventoried data, spatialized maps of carbon dioxide (CO2) flow at high resolution in urban areas are essential for carbon cycle research and carbon reduction management. In this research, Guangyuan, a mountainous city located in southwestern China, which was heavily affected by the 2008 earthquake, was used as a studying case. In this city, gridded data of vertical carbon flows at 1-km resolution was extracted based on point emission sources and other supporting data in Guangyuan. Among the 16,020 grids, 4,465 performed as CO2 emission sources while the other 11,555 as sinks. On the whole, Guangyuan City served as a carbon sink in 2010, with the total net flow of 0.44 Mt CO2 being sequestered and stored by vegetations. The overall pattern of emission sources and sinks matched well with local land-use patterns. The hotspots of CO2 emissions appeared in the built-up areas along local valleys, as well as low mountainous areas. On the contrary, large areas of carbon sinks were mainly distributed in the mountainous areas of northwest and northeast parts of Guangyuan. With regard to the distribution of gridded emissions, an evidently clustered characteristic was identified. The proportion of the largest individual emission grid accounted for 12.01% of the total emission. The cumulative percentage of gridded emissions indicated that supervision of 0.06% of the total area could enable effective management of approximately 60% of the total emissions in Guangyuan. Thus, the spatialized gridded data of carbon flows produced in this research can provide significant policy implications for urban planning and regional carbon flow mitigation.