How does the urbanization level change in the Yangtze River economic belt, China? A multi-scale evaluation using DMSP/OLS nighttime light data

Abstract

Based on DMSP/OLS nighttime light data, we select the Yangtze River Economic Belt (YREB) as the research area to evaluate the urbanization level of the YREB at provincial, regional, and county scales. First, we construct the compounded night light index (CNLI) based on the nighttime light data by extracting the integrated light intensity (I) and the built-up area (S) of the Yangtze River economic belt from 1992 to 2012, and we respectively calculate the CNLI of the YREB at the province, regional and county scales of the YREB such that we can comprehensively analyze the spatial and temporal distribution characteristics and dynamic changes of the process of urbanization in the YREB. Second, we construct two traditional urbanization level evaluation index models based on socio-economic statistics: The integrated urbanization level index model (IU) and the urbanization composite index model (Cf), which are used to respectively calculate the urbanization levels at the province, region, and county scales of the YREB. Finally, we establish a multi-scale urbanization model of CNLI, IU, and Cf in order to perform correlation analysis of CNLI, IU, and Cf on different scales. The results show that CNLI can objectively reflect the development status of urbanization level, and provide a new index and method for better monitoring the state of urban development and evaluating the annual change of urbanization.