Assessing coastal dynamics in the Bangladesh delta: applications of remote sensing and GIS for monitoring climate impacts

The Bangladesh Delta is one of the most vulnerable and dynamic coastal regions in the world, significantly impacted by factors such as sea level rise, cyclones, sediment redistribution, and extensive anthropogenic activities. Cloud-free Landsat imagery of three time series (1994, 2009, and 2024) have been used to delineate the coastal dynamics, land-use changes, and ecological shifts through a comprehensive GIS framework. The results indicate a significant landward migration of the tidal front at the delta’s distributary mouths, along with a 42% reduction in deep-water zones and a substantial 218% increase in wetlands and sub-tidal flats. Although mangrove forest initially expanded to 2,454 km² in 2009, but subsequently declined sharply to 1,633 km² by 2024, representing a net loss of approximately 30%. Vegetation health has also deteriorated significantly. The proportion of pixels classified as stressed increased from only 0.8% of the study area in 1994 to 41.6% in 2024. This decline is further supported by hydrological indicators, with areas exhibiting very high moisture rising from 1.1% to 27.9%, suggesting severe water-logging and increasing salinity. Spatial analysis identifies major erosion hotspots within the delta’s complex network of creeks, as well as sediment accumulating zones that may be suitable for planned land-reclamation interventions. Overall, the quantitative evidence generated by this study provides critical baseline information for climate-resilient zoning, targeted mangrove restoration, and improved drainage planning under the Bangladesh Delta Plan 2100, supporting long-term sustainable coastal management and adaptation to climate change.