Decoding and Mitigating the Urban Heat Island Effect in Kolkata: A Two-Decade Geospatial and Remote Sensing Analysis

Advay Nathany

Abstract: The Urban Heat Island (UHI) effect, wherein urban areas exhibit significantly higher temperatures than their rural surroundings, has emerged as a critical environmental challenge in rapidly developing cities. In Kolkata, one of India?s most densely populated and climatically vulnerable megacities, the intensification of UHI threatens thermal comfort, public health, and energy sustainability, particularly in dense informal settlements. This study provides a comprehensive two-decade (2005?2024) spatiotemporal assessment of UHI dynamics using multi-temporal Landsat datasets processed on the Google Earth Engine (GEE) platform. By integrating Land Surface Temperature (LST) and Normalised Difference Vegetation Index (NDVI) across seasonal snapshots (January, April, July and October), we identify and quantify thermal hotspots and vegetation loss at neighbourhood-level resolution. The analysis reveals a pronounced expansion of high-LST zones- most notably during the pre-monsoon season- concurrent with a progressive decline in NDVI values across the urban footprint. Seasonal patterns show April as the hottest period, January as the coolest, and October increasingly retaining elevated post-monsoon temperatures, indicating reduced thermal recovery. A correlation analysis between LST and NDVI confirms a strong inverse relationship, reinforcing the role of vegetation in mitigating surface heating. The findings highlight substantial SUHI (Surface Urban Heat Island) intensification over the past two decades, driven by rapid urbanisation, land cover transformation, and loss of green buffers. The study underscores the urgent need for integrated, climate-conscious urban planning strategies that prioritise vegetation restoration, green infrastructure expansion, and sustainable land use policies to mitigate UHI impacts and enhance urban resilience in Kolkata. The evidence generated from this two-decade geospatial analysis offers actionable intelligence for municipal authorities, urban planners, and environmental policymakers. Targeted interventions such as urban afforestation, riverfront greening, reflective surface mandates, and microclimate-sensitive zoning could substantially reduce heat exposure in vulnerable neighbourhoods. Incorporating these measures into Kolkata?s climate adaptation framework will not only curb UHI intensity but also advance the city?s alignment with the United Nations Sustainable Development Goals, particularly SDG 11 (Sustainable Cities and Communities) and SDG 13 (Climate Action).

Keywords: Urban Heat Island, Remote Sensing, Land Surface Temperature, Climate Resilience, Geospatial Analysis

How to Cite?: Advay Nathany, "Decoding and Mitigating the Urban Heat Island Effect in Kolkata: A Two-Decade Geospatial and Remote Sensing Analysis", Volume 15 Issue 1, January 2026, International Journal of Science and Research (IJSR), Pages: 662-675, https://www.ijsr.net/getabstract.php?paperid=SR251231152313, DOI: https://dx.doi.org/10.21275/SR251231152313