Like groynes, newly-built breakwater structures are, as of recently, being submerged to reduce their visual impact and improve water quality. An additional negative aspect is their impact on the landscape. In addition, water exits from the gaps, creating strong rip currents that can even lead to causalities on the Mediterranean coast, although swimmers and divers think they are in a safe area. North of Porto Garibaldi (Emilia Romagna) 74 detached breakwaters follow each other for 9 km of coast, between Porto San Giorgio e Casabianca (Marche) 61 elements protect 5.5 km of beaches, but the record is Pescara (Abruzzo), where 243 breakwaters cover more than 23 km of coast.īreakwaters at Torre Mucchia Beach, Italy (Photo: Enzo Pranzini)īreakwaters can sometimes be responsible for a lower water quality due to the poor water circulation. In some areas of Italy detached breakwaters are quite common: e.g. In Croatia the detached breakwaters are generally used as ship berths. Detached breakwaters (offshore, parallel to the coast) are the most frequent shore protection structures along the Italian Adriatic coast, but rarely on the Croatian side. Groynes in Misano, Italy (on the left) and Supetar, Croatia (on the right) (Photos: Enzo Pranzini and Ivan Sekovski)Ī breakwater is often a shore-parallel coastal structure (usually of rock and rubble mound) projecting into the sea, that protects a shore area by reducing the wave energy. They can be built with the same materials as the emerged ones. at Pellestrina (Veneto), Punta Marina (Emilia-Romagna) and Fano (Marche). More frequently, they reach emerged or submerged breakwaters and create a sort of a ”pond”, e.g. Along the Adriatic coast this solution is not used, but submerged segments are added as extensions to traditional groynes, such as south of Eraclea Mare. These sediments are deposited downdrift since the current velocity reduces after passing over the crest. One should be careful with the use of groynes, especially larger ones, because they have long lasting and often undefined wider impact on coastal processes.Ī more recent alternative are submerged groynes, which have limited impact on the landscape and allow sediments to pass over them after the formation of a ramp. Such functions can be improved by creating a pedestrian walkway on the crest, possibly protected by railings or stones (like at Cavallino, Veneto, and Pescara, Abruzzo), and, when necessary for hydraulic reasons, a small platform at the tip. They are among the most liked coastal protection structures by the stakeholders, since they allow fishing activities and sunbathing. Groynes are constructed more frequently on the western side of the Adriatic than on the eastern one, although in Croatia they have started emerging recently. In Croatia, natural-limestone material is often used. Groynes are often constructed of rocks (because of durability, repairability, and ability to absorb more wave energy), but wooden groynes, steel groynes, rubble-mound and sand-filled bag groynes, or groynes made of concrete elements, can also be found. If applying groynes, it is preferable to do it together with the beach nourishment activities, to reach maximum positive effects. Since groynes induce an updrift beach expansion, and trigger a downdrift erosion, a series of groynes acting together to protect a beach (“groyne system”) is often needed, due to this domino effect. A groyne is a shore protection structure built perpendicular to the shoreline to reduce the longshore drift and to trap sediments (I, Γ, Y, ৲ configurations are frequently used).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |