Quantifying Riverbed Scour and Hydrodynamic Changes Induced by Bridge Piers in a Diurnal Tidal Estuary: A Pre-Construction Assessment of May Chai Bridge, Hai Phong City
DOI:
https://doi.org/10.29227/IM-2026-01-01-019Keywords:
bridge pier scour, 3D hydrodynamic modeling, sediment transport, MIKE 3 FM, morphodynamic processesAbstract
Bridge construction in tidal estuaries poses significant risks to structural stability through pier-induced scour, yet comprehensive pre-construction assessments remain rare in Southeast Asia's dynamic river systems. This study quantified projected hydrodynamic and morphological impacts of the planned Mai Chai Bridge on Vietnam's Cam River using high-resolution MIKE 3 FM simulations before construction commenced. The model, calibrated against 2021–2022 field measurements (NSE = 0.92 for water levels, 0.56–0.67 for waves, 0.62–0.73 for sediment transport), revealed dramatic seasonal contrasts in pier impacts. During flood season, piers reduced upstream velocities by up to 80% (from 0.9 m/s to 0.1–0.2 m/s), generating complex turbulent wake patterns that extended 500–550 m downstream before flow recovery. Maximum seasonal scour depths of 0.4–0.5 m were projected adjacent to pier foundations, with pronounced asymmetric erosion along the left bank driven by channel curvature and secondary circulation. In contrast, dry season bidirectional tidal flows produced near-equilibrium conditions with minimal net morphological change (±0.05 m/season). These findings demonstrate that cumulative flood season scour dominates long-term foundation stability despite dry season recovery, with critical implications for pier embedment design, differential scour protection strategies, and adaptive maintenance protocols. This pre-construction modeling approach provides a cost-effective framework for predictive infrastructure assessment in monsoon-influenced tidal rivers worldwide.
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