Urban expansion dynamics and modes in metropolitan Guangzhou, China

Urbanization changes urban landscapes and results in ecological and environmental problems. To solve these problems, it is essential to quantify the dynamics of urban expansion and better understand the modes of urban sprawl. This study evaluated urbanization in metropolitan Guangzhou, China from 1990 to 2020 and explored its modes of urban growth using Landsat Thematic Mapper images and simulated landscape maps based on the Conversion of Land Use and its Effects (CLUE) modeling framework. The results indicate that Guangzhou has experienced great expansion, characterized by the tripling of its total urbanized area within the last 20 years, and it is projected to continue expanding into less developed areas (agricultural and forest land). The results also show that adjusting the land-use structure sometime has a greater effect on the formation of the urban landscape than spatial restriction policies. Three urban expansion modes (infilling, edge expanding, and leapfrogging) were observed to occur simultaneously along with a shift in their relative dominance, which reveals a spiraling urban process.