Understanding Urban Expansion and Its Landscape Responses with Long-Term Landsat Data in Guangzhou, China

Quantifying the spatio-temporal pattern of urban expansion is essential to understanding the ecological consequences of urbanization and supporting optimal urban management strategies. As one of the most developed regions in China, Guangzhou has experienced rapid urban expansion over the past decades. However, little is known about the detailed process of urban expansion across long-term periods. Combining remote sensing data with GIS techniques, we attempted to quantify the spatio-temporal pattern of urban expansion in Guangzhou. We mapped the urban landscape in Guangzhou using Landsat images between 1973 and 2017. The urban land developed and change process was also examined, including urban expansion direction, urban expansion types, and landscape responses to urban expansion. The results showed that the building nearly increased by 90-fold from 1973 to 2017, and over half of the newly developed buildings mainly came from farmland. Edge expansion is the main type of urban growth. The urban trajectory shows that the expansion mainly occurred in the southwest to northeast direction. Urban growth led to radical changes in the urban landscape, leading to sharp decreases in soil and farmland. The results from this study provide key information for future planning to make eco-friendly megacities as well as sustainable development.