Quantifying spatiotemporal patterns of shrinking cities in urbanizing China: A novel approach based on time-series nighttime light data

The shrinking of cities has become an increasingly global phenomenon, posing challenges for sustainable urban development. However, most focus remains on Europe and North America, and relatively little attention has been paid to the East Asia, especially the urbanizing China. Nighttime light (NL) dataset and its features (long-term time-series free access and large coverage) provide an alternative means to quantify shrinking cities. Here, we developed a new approach to identify shrinking cities and measure urban shrinkage, using corrected-integrated DMSP/OLS and NPP/VIIRS NL data. Based on this approach, we quantified the spatiotemporal patterns of shrinking cities in China from 1992 to 2019. Our study identified 153 shrinking cities in China during the study period, accounting for 23.39% of all 654 cities. These shrinking cities were widely distributed across eight economic regions and most provinces. The number of shrinking cities changed periodically and peaked following the Asian Financial Crisis in 1997 and again after the Global Economic Crisis in 2008. The cities that experienced the greatest shrinkage intensity were mainly distributed in northeast China, with severe urban shrinkage occurring between 2008 and 2013. The new approach proposed in this study can effectively identify shrinking city hotspots and key periods of urban shrinkage. Our findings suggest that sustainable urban development in China must consider shrinking cities, which are faced with challenging and urgent sustainability issues different from those by rapidly growing cities.