Spatiotemporal Differentiation of Impervious Surface in the Beijing–Tianjin–Hebei Urban Agglomeration From 2000 to 2019

Since impervious surface (IS) is an important indicator of urbanization level and ecological environment, studying the spatiotemporal differentiation of IS has become an urgent issue in urban sustainable development research. Different from previous IS monitoring at intervals of several years, this letter proposed a new spatiotemporal differentiation method of IS on an annual time scale in the Beijing–Tianjin–Hebei (BTH) urban agglomeration from 2000 to 2019. The results show that IS in the BTH has increased steadily, from 16743.78 km2 in 2000 to 28270.06 km2 in 2019. The growth trends of IS are mostly characterized by outward expansion centered on the urban area, and there are obvious differences in the IS expansion of cities within BTH due to different urban patterns and development strategies. These results can provide references for the urban development and planning of national-level urban agglomerations.