Identification and quantification of localized urban heat island intensity and footprint for Chennai Metropolitan Area during 1988-2023

Rapid urbanization has altered land use and land cover to accommodate the growing population. This shift towards urbanization has resulted in the UHI effect, where the inner urban core is notably warmer than its surroundings. Existing research on UHI has primarily focused on major cities at the regional scale, leaving a gap in addressing the effect of extreme UHI zones within a city. This study bridges the gap by developing a methodology to quantify the impact of LULC change on the localized UHI zones within the urban areas, which will assist policymakers in mitigating urban heat. LULC change matrix analysis and LST retrieval were done from the Landsat 5 and 8 images acquired between 1988 and 2023. Representative study sites that intersected with the LULC conversion from water bodies and vegetation to other LULC and which showed maximum UHI were selected. Mean LST was calculated for the proximity of 1000 m around the selected areas. The developed methodology was applied to the Chennai Metropolitan Area in Tamil Nadu, India. The conversion of Pallikaranai marshland to the Perungudi dumping ground (PDG), and the green cover to the Kodungaiyur dumping ground (KDG) has led to an average increase in UHI intensity of 0.21 degrees C/year and 0.15 degrees C/year, respectively. The UHI effect is felt at the distance of 450 m from PDG and 550 m from KDG, which have shown that the life within the proximity are expected to experience the UHI effect. Therefore, it is imperative to alleviate the rising UHI around the selected areas. This developed methodology can be applied globally to select the targeted UHI zones for sustainable urban planning to mitigate urban heat.