Monsoon-driven waves induce a prevailing recession in mangrove forests across the Ganges-Brahmaputra-Meghna Delta

The role of monsoon-induced wave action in driving mangrove loss in deltaic settings remains underexplored in comparison with the role of anthropogenic activities. Here, we reveal that the Ganges-Brahmaputra-Meghna Delta (GBMD), the world’s largest mangrove ecosystem within a monsoon-dominated region, exhibited an increased trend in total mangrove area at a rate of 133.3 ± 6.7 ha yr-1 from 1988 to 2022, despite a landward retreat of the mangrove shoreline at 5.98 ± 1.56 m yr-1. Monsoon-driven wave action is the primary driver of mangrove loss, with sea-level rise and tropical cyclones acting as critical amplifiers that exacerbate wave-driven erosion. In contrast, tidal currents promote sediment redistribution into channels, backshore areas, and around barrier islands and sandbanks, thereby fostering mangrove colonization and largely compensating for mangrove loss. Our findings highlight how southwest monsoon-induced waves drive mangrove loss, shedding light on the mechanisms underlying mangrove degradation in wave-dominated coastal areas. Monsoon-driven waves, amplified by sea-level rise and cyclones, drove shoreline retreat at around 6 meter per year in the Ganges-Brahmaputra-Meghna Delta, whereas tidal currents enhanced sediment redistribution, increasing total mangrove area by 133 hectares per year from 1988–2022, based on Landsat image analysis.