Multi-Decadal Shoreline and Morphological Change of Jambudwip Island Using Landsat and DSAS (1972–2026).

Abstract

The Jambudwip Island in the Indian Sundarbans is exposed to rapid shoreline migration and morphological instability. This study quantified shoreline and areal changes over 54 years (1972–2026) using ten cloud-free Landsat MSS, TM and OLI/TIRS scenes. Water–land boundaries were delineated using the Normalized Difference Water Index (NDWI), and shoreline change was evaluated in the Digital Shoreline Analysis System (DSAS) using 226 transects spaced at 100 m. End Point Rate (EPR), Linear Regression Rate (LRR), Net Shoreline Movement (NSM) and Shoreline Change Envelope (SCE) were used to characterize the magnitude and rate of change. Short-term analysis showed the largest erosional episode during 1980–1990 (690.64 ha), whereas the largest accretion occurred during 1990–1995 (765.26 ha). After 2000, the island was predominantly erosional, including a net loss of 90.43 ha during 2020–2026. Over the full period, island area declined from approximately 876 ha to 313 ha. The maximum EPR values reported in the thesis ranged from −90.41 m yr⁻¹ for erosion to +42.01 m yr⁻¹ for accretion, while NSM reached approximately −4000 m and +2000 m. The spatial pattern indicates greatest instability along the southern and western margins. The results demonstrate the value of multi-temporal Landsat data and DSAS for long-term monitoring of small, erosion-sensitive deltaic islands, while also highlighting the need for higher-resolution imagery, field validation and hydrodynamic information in future assessments