Monitoring changes in the impervious surfaces of urban functional zones using multisource remote sensing data: a case study of Tianjin, China

Previous research on urban impervious surface monitoring has ignored the differences, spatial patterns, and driving factors of impervious surfaces among the various functional zones in cities. In this paper, we extracted the impervious surface coverage of Tianjin in 1990, 1995, 2000, 2005, 2010, and 2015 based on the Classification and Regression Tree model. Then, using the methods of quantitative geography, we systematically analyzed the spatiotemporal variations of impervious surface coverage among the functional zones in Tianjin from 1990 to 2015. Additionally, the driving mechanisms of impervious surface growths among different functional zones were investigated. The results showed that (1) the growth of impervious surfaces shows two spatially separate core areas of growth. The core functional zone (CFZ) had the highest impervious surface coverage, and the ecological conservation zone (ECZ) had the lowest impervious surface coverage. (2) High-high aggregation regions of impervious surface coverage were mainly located in CFZ, while low-low aggregation regions of impervious surface coverage area were mainly located in ECZ. (3) Influences of social-economic factors on area growths of impervious surface are stronger in urban function expanded zone, coastal city key development zone, Beijing-Tianjin coordinated development zone, and urban-rural coordinated development zone than those in CFZ. Our results can provide a point of reference for decision-making regarding urban planning management.