Tidal currents and the dynamics of sand dunes in the Khuran strait – the Persian gulf

The Khuran Strait, situated between Qeshm Island and the Iranian mainland in the Persian Gulf, is a dynamic region characterized by short crested small waves, strong tidal currents, and significant sediment transport. The present study aims to investigate the physical processes of sand-mud mixtures in the strait and dynamics of sand dunes in the middle section. To achieve this, comprehensive field measurements, including vertical current profiling, directional waves, water levels, wind, and sediment grab samplings, were conducted to gather the necessary data to investigate the pattern of sediment transport. A two-dimensional depth-averaged coupled hydrodynamic and sediment transport model was developed, enabling the simulation of sediment transport in the study area. The model outputs show that current velocities at the middle part are high enough (1.85 m/s) to move the sand dunes and cause severe erosion. The morphodynamic model was validated through hydrographic surveys conducted at the Rajaee access channel during 2 distinct periods. Comparisons between predicted and observed sediment transport rates reveal that the estimated rate of 130,000 m³/year aligns reasonably well with historical rates recorded from 2008 to 2010 and 2010 to 2011. This correlation supports the model's effectiveness in capturing the sediment transport dynamics of the Khuran Strait. The outcome of this study confirms that strong tidal currents, rather than wave action, dominate sediment transport in the Khuran Strait. The symmetrical tidal regime and influence of mangroves contribute to stable yet active sediment dynamics, particularly around proposed probable infrastructure sites that are to be constructed in future. Limited dune migration suggests a near-equilibrium state. These findings are vital for assessing scour risks and support the use of integrated modeling and monitoring in similar tidal environments.