Morpholithodynamical changes of the beach and the nearshore zone under the impact of submerged breakwaters – a case study (Orłowo Cliff, the Southern Baltic)

Abstract

Submerged breakwaters (SBWs) were used for the first time on the Polish coast in 2006, in the western coast of Gdańsk Bay, in the area of Orłowo Cliff. They were built to prevent the abrasion and inundation of areas situated in the hinterland, especially in the conditions of storm surges. The main objective of the study was to determine their effect on the morphology and grain size composition in the seashore and nearshore zone. Based on the conducted research and analysis, it has been found that the construction has a minor impact on the modification of the shore and nearshore zone morpholithodynamics, which is evidenced by a sinuate shape of the shoreline and a relatively stable cape in the central part of the area, present both before (1966–2005) and after SBWs were built. Furthermore, the progressive abrasion, the lack of significant changes in the morphology and particle size distribution of the beach and the nearshore zone, as well as the fact that those changes are limited only to the immediate surroundings of the submerged breakwaters prove their neutral impact.