Satellite Nighttime Light and Digital Elevation Data to Assess Urban Expansion in Floodplains of Dhaka City

This study aims to evaluate the potential of DMSP/OLS nighttime light data to investigate human presence and activity in Dhaka City, Bangladesh. The study explores the sensor's ability to detect and monitor urban expansion patterns and human presence and activity at a regional scale. Thematic land cover maps revealed a rapid expansion of built-up areas within the 43-year study period, increasing from 35 km² in 1972 to 378 km² in 2015, representing a net gain of approximately 980% and an average annual growth rate of 6%. Notably, this growth rate was significantly higher in peripheral areas (2903% and a yearly expansion rate of 8%) compared to the central city area (Dhaka City Corporation) (460% and an annual expansion rate of 4%). This substantial urbanisation has primarily occurred in Dhaka's northern, northwestern, and southwestern sectors, transforming previously agricultural land, vegetation cover, wetlands, and water bodies. The findings demonstrate the utility of DMSP/OLS imagery for detecting human activities and presence in the Dhaka region, providing valuable insights into urban expansion patterns and their implications for environmental and social dynamics.