Spatiotemporal Evolution Patterns and Driving Factors of Urban Expansion in Guizhou Province: Evidence from Nighttime Light Data

Situated in southwestern China, Guizhou Province is a typical mountainous karst region. Constrained by its complex topography, urban expansion here diverges significantly from that of traditional plain cities. As a unique socio-economic proxy, nighttime light (NTL) data effectively captures urban expansion and human activity intensity, thereby facilitating the monitoring of urban dynamics and informing regional development strategies. Drawing on continuous nighttime light data from 2000 to 2023, this study systematically analyzes the spatiotemporal evolution of urbanization in Guizhou Province. The expansion processes are quantified by assessing Total Nighttime Light (TNL) alongside the spatial patterns and morphological characteristics of built-up areas. Subsequently, guided by the framework of new-type urbanization, this research investigates the underlying driving mechanisms behind this regional urban growth. The results indicate: Guizhou Province experienced substantial urbanization from 2000 to 2023. This trajectory featured a high-speed expansion phase (2000–2015) followed by a stabilization period (2015–2023), marking a clear transition from quantitative growth to qualitative consolidation. However, against this backdrop, regional development disparities persist. The Qianzhong area, with Guiyang as its core, has consistently served as the economic center of the province. This concentration leaves surrounding counties and cities relatively underdeveloped, forming a distinct core-periphery spatial pattern characterized by a highly fragmented overall urban structure. While higher-tier centers—namely the provincial core Guiyang, the sub-center Zunyi, and other prefecture-level cities—show clear spatial agglomeration, lower-tier districts and counties remain scattered, forming a distinctive layout of ‘macro-dispersion with micro-clustering’. Analysis of the spatial associations reveals that socio-economic factors provide the primary explanatory power for urban expansion, while the explanatory capacity of natural constraints remains relatively weak. The coupled spatial pattern of ‘economic development, transportation improvement, and population agglomeration’ exhibits a significant spatial correlation with regional urbanization. By aligning the actual urban development dynamics of Guizhou with macro-policy frameworks, this study formulates targeted policy recommendations. These proposals provide a valuable reference for optimizing the developmental pathways of similar mountainous cities.