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Based on social network and regression analyses, this study conducted research with regard to the spatial correlation and effect of carbon emissions in urban agglomerations of the Pearl River Delta (PRD) with the data of prefecture-level cities in Pearl River Delta urban agglomerations from 2001 to 2019. As the results suggested, ① the carbon emission links among cities in PRD urban agglomerations were relatively loose, the subordinate structure changed frequently, and the carbon emission exchanges and cooperation among cities need to be strengthened. ② The core-periphery structure of the spatial correlation network of carbon emissions was loose to a certain extent, the control ability of the central city to the overall network structure was weakened, and the marginal cities gradually changed from being controlled to adopting a controlling role. ③ The improvement in the overall network tightness and stability and the breaking of the network hierarchical structure significantly reduced regional carbon emissions, whereas the improvement in individual network centrality significantly promoted urban carbon emission reduction. The above analysis will help to provide reference for coordinating carbon dioxide emission reduction and low-carbon city development policies.

Effective measures to improve road accessibility during storms are required as traffic congestion caused by storm floods increasingly constrains the efficiency of urban commuting. However, flood impacts on urban road connectivity are not yet well assessed due to inaccurate simulation of flood processes in urban areas where high-resolution data for drainage networks and gauged hydrological data are insufficient. Thus, this study assesses flood impacts on road network connectivity in an urban area of southern China through joint modeling of 1-D hydrodynamic processes in drainage networks and 2-D flood inundation processes on roads using MIKE Urban and MIKE 21. High-resolution DEM images of 5 m and a drainage network of 5635 pipelines were used for urban hydrological simulation. Flood depths were gauged for model calibration and validation by recruited volunteers in the context of citizen science. The results show that road network connectivity decreases as rainfall increases. More than 40% of road connectivity is lost in the study area when a 1-in-100-year return period rainfall occurs. The study results can help to inform more adaptive strategies for local flood control. The study methods are also applicable to improving urban hydrological modeling in broader regions., (© 2022. The Author(s).)