Coastal defence structures - groynes

Groynes are solid structures usually built perpendicular or at an angle to the coast. They are usually relatively short shore-connected structures (wooden barriers, concrete e.g. 'fish tails' or rock) built along the coast and designed to trap sediment on the beach.

Caption: Wooden groynes protecting the beach at Eastborne. Note the way the gravel beach is higher on the right side of the picture, the updrift side and lower on the left, the downdrift side. This indicates that the longshore drift is from right to left.

They can be used along sand and shingle shores for sea defence either alone and/or in conjunction with sea walls, revetments, offshore breakwaters and beach nourishment. The term is also used in relation to 'groyne fields' which are constructed on intertidal sand and mudflats to trap silt and sand to encourage foreshore and saltmarsh accretion.