Vessel-wave induced potential longshore sediment transport at Aegna Island, Tallinn Bay

Abstract

The potential impact of high-speed vessel wakes on the longshore drift of semi-sheltered, medium-energy beaches is evaluated based on recent studies in almost tideless Tallinn Bay, the Baltic Sea. Energy flux and wave propagation direction of vessel wakes is estimated based on high- resolution water surface profiling in summer 2008. The wind-wave time series in 1981-2008 is modelled on the basis of a simplified scheme for a long-term wave hindcast with the use of a triple- nested version of the WAM model. Longshore drift, created by wind waves and by vessel wakes, is estimated by the energy flux model, also known as the Coastal Engineering Research Centre (CERC) model. Vessel wakes cause longshore drift that in 2007-2008, as compared to the drift produced by wind waves on the SW coast of the Aegna Island at the entrance to Tallinn Bay, had a magnitude about 75% less and the opposite direction.