Unriddle the complex associations among urban green cover, built-up index, and surface temperature using geospatial approach: a micro-level study of Kolkata Municipal Corporation for sustainable city

The research article delves into the background of urban land use and land cover (LULC) change, specifically focusing on built-up expansion, and underscores its significant implications on land surface temperature (LST) and the urban heat island (UHI) phenomenon. This research aims to unravel the intricate associations among urban green cover, built-up index, and surface temperature, specifically within the spatial confines of the Kolkata Municipal Corporation. The primary objective is to comprehensively understand how the conversion of green spaces into built-up areas influences land surface temperature and, consequently, the urban heat island effect. Employing a geospatial approach, the study utilizes normalized differential vegetation index (NDVI), normalized differential built-up index (NDBI), and land surface temperature (LST) data extracted from Landsat imagery spanning four temporal points (1990, 2000, 2010, and 2020). The borough-level analysis offers a micro-level perspective within the limited urban space of Kolkata Municipal Corporation. Correlation analyses and scatter diagrams are employed as tools to scrutinize the complex relationships between these variables, providing a robust methodology for the investigation. The research underscores the significant impact of urbanization on the study area, revealing a consistent trend of converting green spaces into built-up areas over the studied decades. This transformation has led to a reduction in green coverage and a concurrent increase in surface temperatures. The study reveals compelling correlations and patterns through NDVI, NDBI, and LST analyses, emphasizing the urgency for serious attention from urban planners, environmentalists, and ecologists. The findings highlight the pressing need for the development of appropriate policy frameworks to ensure the future sustainability and health of cities.