Rapid urbanization and its driving mechanism in the Pan-Third Pole region

Rapid urbanization increasingly influences ecosystem stability and regional urban sustainability. Pan-Third Pole cities located in high-altitude regions around the Tibetan Plateau, Pamir, and Indo Kush have experienced rapid urbanization during the last few decades; however, an understanding of the urbanization rate and its driving mechanism remains lacking. Here, we investigate the urban land transformation dynamics of 14 major Pan-Third Pole cities and analyse their driving factors over two periods (2000-2010 and 2010-2017) based on the interpretation of historical Google Earth imagery using deep learning techniques. Our results show that the urbanized area has increased from 2809 km² to 4380 km², with an annual growth rate of nearly 3% during 2000-2017, which is probably the largest increase in the world. The analysis of potential driving factors reveals that population growth dominates urban expansion, elevation is a constrained topographical factor, and neighbourhoods to roads facilitate urbanization. Our findings would benefit policy making for urban sustainability in the most fragile region on Earth.