Illuminated Spaces: Spatial Analysis of Night-time Lights in the Kolkata Metropolitan Area

Abstract

Urban-scapes are illuminated by outdoor artificial lights. This work, in the scope of Nocturnal Geography, employs Night Time Light (NTL) as a parameter associating with urbanization. Focusing on the Kolkata Metropolitan Area (KMA), it explores how city categories and population influence NTL distribution. The study has been conducted on 142 diverse urban sites across six districts—Kolkata, Haora, Hooghly, North 24 Parganas, South 24 Parganas, and Nadia. The sites represent statutory towns (Municipal Corporation, Municipality with outgrowths, Municipality, Cantonment Board) as well as Census Towns. Cartographic and statistical tools were applied to correlate NTL with built-up space and population. Built-up areas were mapped using Global Human Settlement Layer (100 m), population from CIESIN GPWv4.11 (100 m), while NTL intensity (nanoWatts/sq.cm/sr.) was obtained from VIIRS Day/Night Band (463.83 m). The study spans 2013–June 2025 and uses Theil Index alongside mapping to analyze spatial dynamics. Findings indicate a moderately unequal distribution of NTL across KMA. Primacy of Kolkata emerges with concentrated high NTL intensity, contrasted by multiple smaller census towns exhibiting low intensity. Correlations with population, built-up space, distance from city core, and National Highways substantiate these disparities. NTL has more than urban infrastructure. Thus, equitable provision of adequate lighting emerges as a vital component for sustainable urban governance, urban resilience, and ensuring better quality of life in metropolitan regions.