Assessment of the temporal variations of surface water bodies in Dhaka City using Landsat imagery

Abstract Urbanization’s profound impact on urban hydrology was investigated through a comprehensive spatial analysis of water body transformations in Dhaka Metropolitan Region from 2004 to 2021. The study aimed to quantify and map temporal changes in surface water bodies, employing advanced remote sensing techniques and manual digitization of Landsat satellite imagery with high-resolution GIS analysis. Utilizing short-wave infrared and near-infrared bands combined with meticulous manual digitization, researchers overcame limitations of traditional automated classification methods, providing more detailed water body delineation in complex urban landscapes. Results exposed a dramatic water body decline from 68.92 km² (22%) in 2004 to 29.41 km² (9%) in 2021, representing a significant 57.3% reduction. Spatial analysis revealed concentrated losses in rapidly urbanizing areas such as Moghbazar, Malibag, Rampura, and Uttara, with larger wetlands and natural lakes experiencing the most substantial degradation. The research identified critical environmental implications, including increased waterlogging vulnerability, reduced natural drainage capacity, and potential local climate variability. Comparative analysis with previous studies underscored an accelerated rate of water body loss, suggesting intensified urbanization pressures. The methodology not only provides detailed quantification of urban hydrological changes but also offers evidence-based recommendations for sustainable urban development. Findings emphasize the urgent need for integrated conservation strategies, strict zoning regulations, and comprehensive urban drainage master plans to mitigate ongoing environmental transformations in Dhaka’s urban landscape.