Multi-decadal shoreline dynamics and wave climate interaction along the Cox’s Bazar–Teknaf coast, Bangladesh

The Cox’s Bazar–Teknaf (CB–T) coast of Bangladesh is a dynamic sandy shoreline shaped by monsoon waves, sediment redistribution, and human intervention. Previous studiesrelied on sparse observations or trend-based analyses, limiting understanding of how wave forcing influences shoreline variability across seasonal to multi-decadal scales. This study examines the spatiotemporal evolution of the 90 km CB–T coast over 1988–2024. Tidally corrected shorelines were extracted from Landsat and Sentinel imagery using CoastSat, long-term trends were quantified using EPR and LRR, dominant variability modes were identified through EOF analysis, and nearshore wave conditions were simulated using SWAN. Results show strong alongshore heterogeneity, with alternating erosion–accretion in the north, relative stability in the central sector, and persistent erosion in the south, with rates from −13 to +17 m yr−1. The first three EOF modes explain 72.2% of total variance, indicating large-scale sediment redistribution superimposed on localized adjustment. Lagged correlations between wave forcing and shoreline change exhibit a seasonal phase pattern that disappear after deseasonalization, indicating that wave–shoreline variability isprimarily dominated by the annual monsoonal cycle within the resolved timescale. An integrated CoastSat–SWAN analysis of this monsoon-dominated, data-scarce coast clarifies how seasonal wave forcing, fluvial sediment supply, and human modification jointly shape decadal-scale shoreline evolution.