Investigating the spatial interaction between urban expansion and the regional thermal environment in Guangxi Beibu Gulf urban agglomeration of China

Rapid urbanization and its associated surface modifications play a vital role in generating and intensifying the urban heat island (UHI). Numerous research has investigated the impact of landscape composition and structure on urban land surface temperature (LST), yet the spatial clustering and heterogeneity between urbanization and the regional thermal environment remained largely unexplored. Here, we analyzed land use dynamics and LST variations in the Guangxi Beibu Gulf urban agglomeration (GBG_UA) from 2000 to 2020. The spatial relationships between urban expansion and the regional thermal environment were explored by bivariate spatial autocorrelation and coupling coordination degree analysis. The results demonstrated that the land use in the GBG_UA remained relatively stable, except for the expansion of developed land in urban centers. The area of heat island zones clearly increased, leading to an enhancement of the UHI effect. Urban development and the regional thermal environment exhibited a robust positive spatial autocorrelation. The H-H (High-High) and L-L (LowLow) types displayed significant aggregation effects. The H-H cluster areas dominated the central urban cores of prefecture-level cities, while the L-L correlation areas were primarily found in mountainous regions. The overall coupling coordination degree was relatively low, with most areas falling into the moderate dissonance level. While it showed a positive shift, with the regions of concordance levels expanding and coupling coordination degree increased. Our study reveals a close spatial correlation between urban sprawl and the UHI effect. The results can offer valuable insights for optimizing the urban green infrastructure to enhance urban heat mitigation and adaptation.