DEVELOPMENT OF WAVE-TIDE HYDRODYNAMIC MODEL USING DELFT 3D FOR BAY OF BENGAL AND SIMULATION OF NEARSHORE HYDRODYNAMIC AT MEGHNA ESTUARY

The Meghna Estuary is a dynamic system influenced by wave-tide interactions andriver discharge. This highly dynamic nature presents several challenges, includingongoing morphological evolution, rapid erosion and accretion of land, frequent channelshifting, and increased vulnerability to storm surges and flooding. Flood tides pushcurrents inland, while ebb tides drive seaward flow, affected by islands like Sandwipand Hatiya. Strong longshore currents dominate in the wet season due to high riverdischarge, whereas tidal forces are more prominent in the dry season with reducedfreshwater input. The study employs a numerical hydrodynamic model to simulateestuarine currents over a 163 km extent with a 250m × 250m grid resolution. The modelevaluates wave-tide interactions under eight scenarios, covering flood and ebb tides inboth wet and dry seasons during spring and neap tide conditions. Results indicate thatlongshore influenced by tidal amplitude and coastal morphology, significantly impactsediment transport and erosion. At Hatiya (East), ebb tide velocities (up to 0.85 m/s)exceeded flood tide velocities, indicating net sediment transport offshore and potentialerosion, whereas at Sandwip (North), flood tide velocities (up to 0.75 m/s) were higher,suggesting accretion. Strong river discharge enhances current velocities in the wetseason, while tidal forces dominate in the dry season due to reduced freshwater input.The study identifies tidal meeting points, providing insights into coastal erosiondynamics and estuarine stability.