Rapid urban expansion and potential disaster risk on the Qinghai-Tibetan Plateau in the 21st century

Context: Cities are still expanding in many parts of the world in the 21st century, especially in developing regions, where socioeconomic transition has triggered urbanization. The Qinghai-Tibetan Plateau, characterized by its high elevation, developing economy, and fragile environment, has undergone rapid urbanization in the past twenty years, potentially heightening the region’s risk of geological and hydrometeorological disasters. Objectives: This article examines the process of urbanization on the Qinghai-Tibetan Plateau in order to better understand the relationship between urban expansion and population change and to explore whether geological and hydrometeorological disasters threaten urban expansion. Methods: We created a high-resolution urban built-up boundary dataset from 2000 to 2020 based on remote sensing and GIS. By examining the spatio-temporal pattern of urban expansion and its population dynamics from 2000 to 2020 in 15 cities across the Qinghai-Tibetan Plateau, we quantified the urban expansion characteristics and explored the rising geological and hydrometeorological disaster risks urban areas face. Results: The Qinghai-Tibetan Plateau has experienced rapid and uneven urbanization in the past 20 years. The total expansion rate was over 252% – 1.48 and 2.81 times higher than that of China and the world, respectively. Urban expansion exceeded population growth in most cities throughout the whole period. The urban built-up areas and population of the Qinghai-Tibetan Plateau tended to concentrate in the Yellow River-Huangshui River Valley of Qinghai Province and the Yarlung Zangbo River and its two tributaries of Tibet. High-density urban built-up areas and population distribution were exposed to geological and hydrometeorological disasters. The urban boundary dataset produced in this study has better accuracy than the other five existing datasets, for the given area and time range.