Overview
Resuspension and redistribution of sediments induced by propeller wash can significantly influence aquatic ecosystems, particularly at contaminated sediment sites near busy ports and navigation channels. This study presents a numerical modeling method developed to predict the sediment resuspension and subsequent transport processes resulting from ship traffic — fully coupling hydrodynamics, sediment transport, and propeller wash effects within the EFDC+ framework.
Model Development
A computational algorithm was developed to calculate propeller wash effects from one or more ships, including erosion rate and momentum flux. These results were then dynamically linked to EFDC+‘s hydrodynamic and sediment transport engine. Prior to this approach, propeller momentum effects were not represented in the flow field computation, leading to underestimation of sediment dispersion extent.
Key model inputs include propeller revolution speed, ship engine power, and the distance between propellers and the sediment bed — all of which directly influence the maximum scour depth and resuspension intensity.
Validation & Results
The modeling framework was evaluated against a field experiment conducted by the US Navy. The model was calibrated using flow velocities and sediment erosion depths, then validated against resuspended sediment concentrations measured in the water column.
Results demonstrated that incorporating propeller-induced momentum into the flow field substantially improved prediction of horizontal and vertical sediment distributions. The sensitivity analysis confirmed that increased flow energy from propeller momentum caused significant dispersion of resuspended sediments in both longitudinal and lateral directions — an effect that was absent when propeller momentum was excluded from the computation.