Simulated and observed reversals of wave-driven alongshore sediment transport at the eastern Baltic Sea coast

Abstract

This paper aims to analyse the sensitivity of patterns of numerically simulated potential sediment transport along the eastern Baltic Sea coast. The study area extends from the Sambian (Samland) Peninsula to Pärnu Bay in the Gulf of Riga. The magnitudes of net and bulk transport depend largely on how the shoaling and refraction of the waves are resolved. The qualitative patterns of net and bulk sediment transport are almost insensitive with respect to the details of wave transformation in the nearshore and with respect to grain size. The overall counter-clockwise transport along the study area contains two persistent reversals along the coast of the Baltic Sea proper and two frequently recurring reversals along the eastern margin of the Gulf of Riga. Individual years with normal levels of wind speed may host completely different patterns of sediment transport. The location of the most persistent convergence and divergence areas of the net transport acceptably matches the granulometric composition of the nearshore seabed up to a few km from the shoreline.