Simulation of Sediment Discharges during an Outfall Dredging Operation

Abstract

CORMIX-GTS simulations are carried out to study suspended muddy sediment plumes following the discharge of the spoils taken from the seabed during a marine outfall pipeline dredging operation. Single port discharges are considered at three different locations at 400 m, 800 m, and 1200 m from the shoreline with water depths ranging from 3.5 m to 10.5 m. For discharges in the shallow near-shore region at 400 m offshore, most of the dredge materials are deposited at the seabed and the simulated suspended sediment plumes are found to be carrying a concentration of less than 1 kg/m3 of mainly fine silt and clay. For discharges in the deeper far-shore region at 1200 m offshore, the sediment plumes are more elongated and carrying a concentration of more than 3 kg/m3. Iterative simulations are also conducted to analyse the inherent uncertainty in the input data by varying the ambient velocity and the port’s horizontal angle of discharge.