Analysis of urban expansion patterns in the Yangtze River Delta based on the fusion impervious surfaces dataset

Abstract The Yangtze River Delta (YRD) is a highly urbanized region. Understanding the spatial and temporal dynamics of urban land expansion in the YRD is essential for optimizing the distribution of urban clusters and promoting balanced regional development. Existing 30 m global impervious surfaces (IS) datasets are hampered by significant accuracy discrepancies and uncertainties stemming from inconsistent methodologies. Therefore, the Dempster–Shafer (D-S) evidence theory was used to fuse three datasets of the China Land Cover Dataset, Global Land Cover product with Fine Classification System at 30 m, and Global Impervious Surface Area, to analyze the urban land expansion in the YRD from 1985 to 2020. The results indicate that: (1) The fused dataset achieved an overall accuracy of 98.26% and a kappa coefficient of 0.965, notably higher than those of the individual datasets. (2) Urban land expansion in the YRD exhibited distinct phases: slow growth, rapid growth, and rapid decline. The early expansion was more intense in the southern YRD. Later, the northern region expansion accelerated, shifting the development center northward. (3) The urban development pattern of the YRD was predominantly characterized by edge expansion, with the proportion of infilling gradually increasing. Long-term and high-precision data on IS provide a comprehensive understanding of the development patterns of regional urban clusters. The D-S evidence theory enhances the accuracy of IS dataset, serving as a foundation for planning and promoting high-quality urban development.