![]() The prefabrication of concrete elements reduces the environmental impact on the beach, changing the conventional quarry dumping construction by installation of prefabricated concrete elements with a specific design. To reduce the economic and environmental impact of traditional LCSs, a variety of prefabricated concrete structures have been proposed to construct detached breakwaters. Detached breakwaters reduce the longshore transport of sand and may cause or significantly increase erosion in nearby unprotected beaches therefore, sustainable erosion control schemes may be analysed from a global point of view in which single or segmented detached breakwater may be the best solution in a specific coastal area. If the induced beach sinuosity reaches the detached breakwater, a tombolo is formed and the functional behaviour is similar to a T- groyne. The higher the breakwater length and crest freeboard and the lower the gap width and distance to shoreline, the lower the energy transmission and the higher the induced sinuosity of the beach and reduction of sand longshore transport will be. Design of breakwaters series#Figure 1 shows a typical segmented detached breakwater scheme for shoreline erosion control.įigure 1 Segmented detached breakwater scheme Application of detached breakwatersĬrest freeboard, distance to the shoreline, breakwater length and gap width are the principal factors affecting the hydrodynamic field and the corresponding beach response to a series of segmented detached breakwaters. Detached breakwaters can be classified as single or segmented, emerged or submerged, narrow or broad crested, etcetera (see also the article detached breakwaters). Submerged LCSs can also be functionally used as an artificial reef to support a perched beach. ![]() The LCSs for shoreline erosion control are generally constructed with negative crest freeboard (submerged detached breakwaters) or with small positive crest freeboard to minimize the aesthetic impact. ![]() The higher the crest freeboard, the higher the aesthetic impact and the lower the wave transmission to the shoreline is. The term “Low crested Structures” (LCSs) usually designates the most common detached breakwater types, which are made of quarry materials having a low crest which allows significant energy transmission. Sustainable shoreline erosion control measures demand an adequate assessment of economic, social and environmental aspects not only for the construction of the coastal structures, but also for the maintenance and lifetime service as well as the rebuilding or dismantling of structures when their lifetime is over.ĭetached breakwaters usually refer to a category of shoreline erosion control structures most frequently placed parallel to the coast to reduce the energy attacking the coastline. material footprint, reversibility or pollution) (see also ICZM). aesthetic rules or tourism) as well as the environmental impact of construction and service (e.g. wave climate or quarries), the social environment (e.g. The selection of the appropriate technique for shoreline erosion control requires taking into consideration the physical and economic conditions (e.g. Shoreline erosion control structures as groynes and detached breakwaters, beach nourishment or a combination of structures and sediment addition are the most common responses to the risk caused by persistent beach erosion. Beach erosion and the corresponding shoreline retreat cause unacceptable economic and environmental risks in numerous coastal areas. ![]()
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