Coastal Urban Thermal Hotspot Dynamics and Land Surface Temperature Variability in Chennai, India, Using satellite Remote Sensing Data

The urbanization of Chennai, a rapidly growing coastal metropolitan city in southeastern India, has led to significant land use and land cover changes over the past decade, substantially influencing its urban thermal environment. This study investigates the spatio-temporal dynamics of Land Surface Temperature (LST), vegetation variability, and urban expansion in Chennai from 2014 to 2025 using multi-temporal satellite remote sensing data and geospatial techniques. Land Use and Land Cover (LULC) classification revealed a considerable increase in built-up area from 29% in 2014 to 36% in 2025, accompanied by a decline in vegetation cover from 31% to 26%, indicating accelerated urban sprawl and surface sealing processes. Emerging Hotspot Analysis (EHSA) was employed to identify persistent and evolving thermal hotspots across the city. The results demonstrated that hotspot regions occupied 18.49% of the study area, while coldspot regions accounted for only 4.06%. Consecutive Hotspots dominated the thermal landscape, representing 57% of total hotspot patterns, particularly concentrated in highly urbanized. New Hotspots constituted 21%, indicating the rapid emergence of thermal stress in recently urbanized regions. Temporal analysis of LST and Normalized Difference Vegetation Index (NDVI) revealed a strong inverse relationship between vegetation density and surface temperature. The highest NDVI value (0.553) observed in 2016 corresponded with the lowest LST (26.97°C), whereas low NDVI values in 2017 and 2023 coincided with elevated LST conditions approaching 30°C. The findings highlight the significant role of vegetation depletion, impervious surface expansion, and anthropogenic activities in intensifying urban heat island effects. This study demonstrates the effectiveness of remote sensing and GIS-based approaches for monitoring urban climate dynamics and provides critical insights for sustainable urban planning and heat mitigation strategies in rapidly growing coastal cities.