Spatial characteristics of urban heat Islands: Land use-based assessment using Chennai's second master plan

The Urban Heat Island (UHI) effect exacerbates thermal discomfort, energy demand, and environmental stress in rapidly urbanizing cities. While numerous studies analyze UHI, there remains a gap in integrating zoning regulations with Surface Urban Heat Island (SUHI) patterns to assess how land use policies influence urban heat distribution. This study addresses this gap by investigating SUHI variations across land use categories in Chennai, a tropical megacity experiencing rapid urban expansion. Using Landsat 5 TM (2006) and Landsat 8 OLI/TIRS (2022) thermal imagery, the study analyzes Land Surface Temperature (LST), Land Contribution Index (LCI) which measures each land use's contribution to urban heat, Urban Thermal Field Variance Index (UTFVI) which quantifies land use wise urban thermal stress, and building footprint data. Unlike conventional studies that rely on Local Climate Zones (LCZ), land use categories from the Chennai Metropolitan Development Authority (CMDA) Master Plan (2006–2026) serve as an alternative zoning framework. The study provides a framework for identification of hotspots and cold spots across the land use categories provided in the Master Plan. The study also identifies key locations for Atmospheric UHI (AUHI) data collection in the future through data loggers, weather stations, and mobile traverse measurements. Results indicate an LST increase of +2.1 °C in primary residential and +1.8 °C in mixed residential zones between 2006 and 2022, while institutional and reserved forest areas exhibited lower thermal variations. This research contributes to Sustainable Development Goal 11 (SDG 11) by supporting climate-sensitive urban planning strategies for resilient and sustainable cities. • Land use classification used to identify Surface Urban Heat Islands in Chennai. • The proposed framework identified 82 hotspots and 18 cool spots in Chennai. • Urban thermal index shows residential areas fell from ‘Very Good’ to ‘Worst’. • The land surface temperature in residential areas rose more from 2006 to 2022n.