Rekha Das
Independent Researcher
West Bengal, India
Abstract
Urban heat islands (UHIs) represent a significant and growing challenge in rapidly urbanizing regions, particularly in informal settlements where infrastructure deficits exacerbate thermal stress. This study investigates the magnitude and human impacts of UHIs in informal settlements across three Tier-2 Indian cities—Kochi, Lucknow, and Jaipur—each representing different climatic zones (coastal, humid-subtropical, and hot-semi-arid, respectively). Employing a mixed-methods approach, we first derived land surface temperature (LST) datasets from April 2024 Landsat 8 OLI/TIRS satellite imagery, applying the single-channel algorithm to calculate mean daytime LST across delineated informal settlement boundaries and adjacent formal neighborhoods. We then conducted a structured household survey with 200 residents (approximately 33 households per settlement) to capture thermal perceptions, heat-related health outcomes, housing characteristics, and adaptive behaviours. Quantitative analysis reveals that informal settlements register an average LST of 42.3 °C (SD = 2.1), compared to 38.5 °C (SD = 1.8) in formal areas—a UHI differential of 3.8 °C (t = 7.42, p < 0.001). Survey results indicate that 68% of respondents “often” or “always” experience thermal discomfort indoors, 42% report sleep disturbances due to night-time heat, and 61% suffer heat-related symptoms such as headaches and fatigue. Access to cooling technologies is severely limited: only 15% own electric fans and none possess air conditioners, while just 9% utilize municipal cooling centres owing to distance and overcrowding. Despite resource constraints, 82% express willingness to participate in community-driven tree planting, and 68% support the application of reflective “cool roof” coatings. Our findings highlight the interplay between urban morphology, socio-economic vulnerability, and thermal stress, underscoring the need for equity-focused policies. We recommend integrating passive cooling designs—such as cross-ventilation and insulated roofing—into slum rehabilitation programs, implementing subsidized cool‐roof schemes, and embedding informal settlements in municipal heat-action plans. Such interventions promise to mitigate UHI impacts, enhance thermal comfort, and reduce heat-related health burdens among the urban poor.
Keywords
Urban Heat Island, Informal Settlements, Thermal Comfort, Tier-2 Indian Cities, Survey
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