The influence of bidirectional tidal flow on scour mechanisms and morphological changes around the Suramadu bridge piers

The Suramadu Bridge is a vital infrastructure in the Madura Strait, facilitating regional economic connectivity. However, complex oceanographic characteristics—notably bidirectional currents and seasonal variations—pose significant scouring risks to bridge piers, potentially threatening structural integrity. This study models current patterns and sediment transport to analyze scouring dynamics around the piers. Using hydrodynamics model, simulations were conducted for 2024, incorporating bathymetry, tides, wind, and sediment data. Model validation against tidal data showed high accuracy (MAE: 0.1473 m; RMSE: 0.1771 m). Results reveal a tidal-driven west–east bidirectional flow with stable average velocities (0.21–0.25 m/s) across monsoons. Interaction between currents and piers causes upstream flow deceleration and lateral acceleration, triggering deposition and erosion, respectively. Piers P46, P47, and P49 experienced the most significant scouring, with maximum depths reaching -0.250 m, while P37, P41, and P56 remained stable. Erosion trends were spatially and temporally consistent across both west and east monsoons. These findings establish critical monitoring priorities to ensure the bridge’s structural sustainability in alignment with SDG Goal 9.