**Abstract**

The Sundarbans, located along the coastal areas of India and Bangladesh, is the largest remaining single block of mangrove forest in the world, covering approximately 1 million hectares (10,000 km2 ) of the Ganges-Brahmaputra delta. This unique ecosystem is under threat from major disturbances such as sea level rise and alterations in water flows from the Himalayan headwaters. There have been very few studies on the current status and dynamics of the Sundarban's coastline. To address this knowledge gap, we conducted a study utilizing Landsat images spanning from 1975 to 2022. Our findings reveal that the rates and directions of erosion and accretion varied across the different periods. During the 1994–2005 interval, erosion reached its peak with a land loss rate of ~17 km2 per year. However, this rate substantially declined in subsequent periods to ~8 km2 . Accretion, on the other hand, showed a rate of ~7 km2 per year between 1975 and 1988 but declined to approximately ~6 km2 per year between 1988 and 1994. While the accretion rate has declined in recent years, the erosion rate has remained relatively high.

**Keywords:** Sundarbans, Bengal delta, coastline, dynamics, satellite imagery, erosion, accretion
