Two-dimensional coupled wave-hydrodynamic modeling of the northern Bay of Bengal

Abstract

The Bay of Bengal (BoB) has a major influence on the climate and hydrodynamics of South Asia, where complex interactions among tides, waves, and currents pose persistent challenges for coastal communities in Bangladesh. Despite the critical need for accurate regional hydrodynamic characterization, existing modeling studies have not fully addressed the simultaneous calibration and validation of water levels, significant wave heights, and current velocities within a unified coupled framework. This study developed a two-dimensional coupled wave-hydrodynamic model for the northern BoB using the Delft3D modeling suite, incorporating high-resolution bathymetry, river discharge, tidal boundary conditions, and spatiotemporally varying wind and wave forcing. The model was calibrated and validated against observed tide levels, significant wave heights, and current velocities at multiple coastal stations, yielding Pearson’s correlation coefficients of 0.79–0.99 and Nash–Sutcliffe efficiency values of 0.72–0.99 across all parameters. A year-long simulation revealed substantial spatial variability in coastal hydrodynamics, with current magnitudes strongly modulated by tidal phase, pronounced tidal asymmetry near major estuarine systems, and elevated wave activity along exposed southeastern coastal sectors during the southwest monsoon. The model accurately reproduced semi-diurnal tidal patterns, dominant current directions, and seasonal wave characteristics across contrasting coastal environments. These findings demonstrate that the coupled model serves as a robust regional baseline for understanding tide-wave-current interactions along the Bangladesh coast, with direct implications for coastal management, storm surge prediction, disaster preparedness, and long-term climate change impact assessment in this vulnerable region.