A footprint of UHI in India: a systematic review of causative factors, impacts and mitigation strategies

Urban heat island (UHI) is the phenomenon where urban areas possess higher temperature than its surrounding rural areas. The present review examines the factors contributing to the UHI effect and the challenge faced by Indian cities in the context of environmental sustainability and health by referring to the literature of more than 40 cities between 2005 and 2023. The present study reviewed already available research which utilizes remote sensing techniques to study the UHI. This study mainly includes satellite data studies; while some fixed station studies, field observations and instrument measurement studies were also incorporated. The current scenario of UHI research in India highlights that the larger cities are studied the most and the smaller but developing cities still need to be explored for the UHI research. The identified key drivers of UHI are vegetation loss, impervious surface, unplanned urban agglomeration, anthropogenic heat and aggravated energy consumption. Different methods have been studied including different simulation techniques used in UHI research. Furthermore, the present review highlights how India can advance towards creating a more resilient, sustainable, and healthful urban environment through integration of green infrastructure, and execution of policies such as Heat Action Plan (HAP) aimed at mitigating UHI impacts. Finally, this study highlights future key directions to examine understudied UHI layers, i.e., Atmospheric and canopy layer UHI, smaller or medium sized urban centers and encouraged to study the region-specific factors such as topography, morphology and socio-economic factors in order to facilitate sustainable and resilient urban planning in India.