Currents generated by vessel traffic along Seattle´s waterfront

Portions of the seafloor along Seattle´s waterfront that are remediable are being cleaned because contaminant concentrations in the sediments exceed state standards. Prior to the selection of remedial methods, the physical processes affecting sediment resuspension and transport were examined. In this paper, mathematical models of propeller jets are compared with current meter observations to estimate velocities generated near the seafloor by vessels operating along the waterfront. Observations and models yielded a conceptual model where: currents generated by a number of vessels may intermittently resuspend fine sediments; Washington State ferries, idling 40% of the time at a single location, generate persistent currents which influence the local circulation and transport of sediments resuspended by the other vessels. Activities of maritime traffic should be evaluated to understand the resuspension and lateral movement of seafloor sediments in harbor areas, especially where water depths are less than approximately fifty feet