Deciphering and Validation of Urbanization of Metropolitan Region in South Asia using Urban Night Lights (UNL): A Case Study of Kolkata Metropolitan Area (KMA), West Bengal, India

Abstract

Images of brightness in the darkness of night obtained from satellite images are considered evidence of the location and expansion of urban areas. The location of electrification in urban areas dramatically increases the night sky's brightness. The urban expansion of the KMA region from 2001 to the present 2021 has been very high and has had a significant impact on the region's environment and people. In this article, the urban expansion of the KMA region since 2001 has been highlighted through images of urban night lights (UNL) based on decades, and urban expansion has been validated by comparing it with various temperate spatial indices. Through observation, it has been seen that with the increase in the built-up area between 2001 and 2021, the amount of LST and NDBI has increased, and the amount of luminous value of UNL has increased significantly. At the same time, NDVI or MNDWI decreased substantially with the increase in luminous value, which proves urban expansion through deforestation and wetland encroachment.