Chapter 4: Coastal structures
4.3 Detached breakwaters
| European Coasts - An Introductory Survey Chapter 4: Coastal structures 4.3 Detached breakwaters |
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| Fig 81: Detached rubble mound breakwater; North Wirral Coast, near Liverpool, UK | Fig 82: A system of detached breakwaters protects the coast at an eroding river delta; Fiumicino, Italy | Fig 83: A T-shaped breakwater armoured with concrete units. A Tombolo has formed behind it; Calabria, Italy |
Detached breakwaters are typically aligned parallel to the coast or to the prevailing wave crests (see Fig. 81 and Fig. 82). Groynes inhibit the longshore sediment transport by partial blockage of the longshore current. In contrast, detached breakwaters reduce this transport by reducing the forces which sustain the longshore current and which keep the sediment in suspension. They do this by lowering the wave height between the breakwaters and the coastline. As a result, the beach is stabilized.
Accretion behind a breakwater may even lead to a connection between the breakwater and the shoreline: a tombolo has been created (see Fig. 83).
Detached breakwaters are usually of the rubble mound type.
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