Sediment transport modeling of trenching activities: a case study for the Safaniya coastal waters in the Arabian Gulf

Trenching activities are essential for marine infrastructure development but disrupt seabed sediments, impacting sensitive ecosystems such as coral reefs and seagrass meadows. The present study investigates sediment transport dynamics of the Safaniya coastal waters in the Arabian Gulf, by integrating field measurements and numerical modeling to analyze sediment plume dispersion and mitigation strategies. The MIKE 21/3 FM-MT-SW module were validated using the datasets from tide tables, ADCPs and ERA5 wave, while source release terms and parametrization were determined using sediment sampling. This enabled high-resolution simulations during both summer and winter seasons. Results revealed that sediment plumes extend approximately 23 km southward during summer and 28 km in winter, with mean suspended sediment concentration (SSC) exceeding 5 mg/L near the trenching site. Wave-induced sediment transport showed higher significant wave heights (2.4 m) and wave energy (7.24 kJ/m²) during winter, which caused enhanced sediment resuspension compared to summer, where wave heights reached 2 m and wave energy was 5.21 kJ/m². Deployment of silt screens effectively decreased SSC (~ 80% during summer) beyond the trenching area. During the winter season, there was a minor dispersion of sediment outside the containment, attributed to the prevailing seasonal conditions. In the absence of mitigation measures, SSC surpassed the 5 mg/L threshold for 40 to 70% of the simulation period. Under calm conditions, the implementation of silt screens resulted in a reduction of this exceedance to below 20%. These findings highlight the critical role of seasonal hydrodynamics in shaping sediment transport and emphasize the need for adaptive management strategies, including reinforced silt screens, buffer zones and real-time turbidity monitoring, to minimize ecological impacts.