Analysis of the spatiotemporal expansion and pattern evolution of urban areas in Anhui Province, China, based on nighttime light data

Abstract

Based on remote sensing images from National Polar-orbiting Partnership—Visible Infrared Imaging Radiometer Suite–like data and related statistical yearbook data acquired at 5-year intervals from 2000 to 2020, the urbanized areas of cities in Anhui Province, China, were extracted. The characteristics of their spatial and temporal expansion were analyzed in combination with the migration path of the urban center of gravity along with measures of the speed and intensity of urban expansion. In addition, the urban development trends in Anhui were evaluated by combining a nighttime light index with spatial autocorrelation and local autocorrelation methods to reveal the characteristics of the level of urban development and internal structural changes in each city in Anhui. The results show that the cities in Anhui are concentrated in two belt areas in the Yangtze and Huai river basins, and that they expanded outward, with several original urbanized areas as the center. The rate of urban expansion reached its lowest point during 2005–2010 and peaked during 2015–2020. The urbanized areas in Anhui were distributed in a northwest–southeast direction, while the center of urban gravity remained in Hefei City during the study period. The total amount of nighttime light in Anhui’s urbanized areas increased by nearly 10 times over 20 years, with the period of 2010–2020 experiencing particularly high increases in nighttime light. The grayness values of urban lights in each period show clear spatial correlation.