Analysis of land surface temperature and vegetation trends across major Indochina urban centers

Abstract

This study investigates long-term trends in Land Surface Temperature (LST) and vegetation cover in four rapidly urbanizing cities of the Indochina peninsula. These cities include Bangkok, Ho Chi Minh City, Vientiane, and Phnom Penh, and the analysis covers a 30-year period. The objective is to understand how urban expansion has influenced local climate and vegetation dynamics. Using Landsat satellite imagery and the cloud-based computing platform, Google Earth Engine, the Enhanced Vegetation Index (EVI) and LST were estimated and analyzed. The Mann–Kendall (MK) non-parametric statistical trend test was applied to identify significant temporal trends and it’s spatial variation. This study stands out by analyzing 30 years of satellite data to examine changes in LST and vegetation across multiple cities. Unlike earlier research, it also considers how these environmental changes affect population exposure, providing a more complete picture of urban growth impacts. Results reveal consistent increases in LST and declines in vegetation across all cities, with strong spatial correlation in urbanized zones. A notable inverse relationship was observed between EVI and LST, indicating that vegetation loss contributes significantly to local warming. The Mekong River plays a moderating role in Vientiane and Phnom Penh, showing a cooling effect in its immediate surroundings while stabilizing vegetation trends. Population exposure to LST changes was assessed by overlaying trend results with population data. Findings show that approximately 34.84% of the combined urban population, totaling over 9.3 million people, reside in areas with significant surface temperature increases. Among the four cities, Phnom Penh showed the highest affected percentage, while Vientiane had the lowest. These findings underscore the critical need for climate-resilient urban planning and the expansion of green infrastructure to mitigate the impacts of urban heat islands in Indochina’s fast-growing cities.