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 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.

Assessment of the Performance of an Artificial Reef Made of Modular Elements through Small Scale Experiments

“…It is important to understand the local sediment transport processes in the wider area in which the structure will be constructed. The expected impact on coastal morphology of submerged structures should be investigated, at least along the length of the coast which is relatively autonomous in regard to the movement of sand and other sediments, and where the interruption of these movements may have a significant effect on nearby beaches [42]. Evidently, with the present tests, nothing can be said regarding the long-shore sediment transport.…”

“…Usually, coastal protection is focused on the use of rigid structures and these are still perceived as one of the best management strategies to attack erosion problems. Nevertheless, it has been seen that it is not necessarily the best option, problems occur as a consequence of the implementation of these structures, such as acceleration in erosion in front of the structure, alteration to the sediment supply, modification to the longitudinal transport [42]. These negative results are found not only with rigid solutions, it has been observed that the distance of the structure from the beach and its level of submersion must be taken into account when using submerged breakwaters, to avoid increasing the energy that reaches the coastline.…”

A Multidisciplinary Approach for the Mapping, Automatic Detection and Morphometric Analysis of Ancient Submerged Coastal Installations: The Case Study of the Ancient Aegina Harbour Complex

“…Submerged breakwaters constitute a sophisticated engineering concept that is under great development today. It has been found that they are two times more effective than the emerged ones in terms of wave energy reduction, while they prevent siltation [51][52][53]. Construction of modern submerged breakwaters depends on wave conditions and geomorphology of the coast, they are usually built at a distance of 150-200 from the coast and a depth of 3-5 m. The ancient conical rubble structure arrays of Aegina are found at deeper waters (8-11 m paleo-depth) while their distance from the paleoshore of −3.8 m varied between 220-270 m during their construction.…”

Beach Gravels as a Potential Lithostatistical Indicator of Marine Coastal Dynamics: The Pogorzelica–Dziwnów (Western Pomerania, Baltic Sea, Poland) Case Study

“…Studies on geodynamic processes and lithodynamics of the coastal zone are essential in different branches of the economy (e.g., fisheries, tourism) and in maritime spatial planning [24,[31][32][33][34]. Increased coastal erosion resulting from a sediment deficit, related to a reduction of river input, dredging processes, and coastal embankments, affects the formation of narrow beaches composed of relatively coarse sedimentary components.…”