Dynamics of sediments disposed in the marine coastal zone near the Vistula Lagoon inlet, south-eastern part of the Baltic Sea

The article discusses the possibility of protecting the shore by disposing of dredged material at shallow depths. An example of a permanently eroded open marine shore segment located south of the Vistula Lagoon inlet (south-eastern part of the Baltic Sea) is considered. This shore segment is permanently caused by downstream erosion due to the moles bordering the entrance to the Vistula Lagoon (Baltiysk Strait) and interrupting longshore sediment transport. Changes of sediment distribution resulting from a demonstration disposal of clean fine sand at depths of seven to nine metres opposite the eroded segment of the shore are examined. A supplementary numerical modelling analysis of sediment transport for different winds showed that the disposed material is transported northward or southward alongshore depending on the wind direction, and almost none of it is stored at the shore slope. The demonstration disposal and numerical modelling results demonstrate that the only way to use the dredged material to protect the eroded shore near the inlet of the Vistula Lagoon is to dispose it directly onto the beach and not into the shallow water nearby.