Groynes

Bournemouth's seven miles of beach are the areas biggest asset, holiday makers and locals alike and Bournemouth Borough Council have invested heavily to protect the area through their Beach Management Scheme. This is a 17 year program of work to protect Bournemouth's coastline. The cliffs in the area are very soft and crumbly, suceptable to landslide, these landslides are a threat to beach huts as strong winter storms can cause the soft and crumbly cliffs to slide down towards the prom and impact the beach huts and promenade.

The ambitous project includes plans to replace Bournemouth's existing 53 groynes, construct three new groynes and to replace the groyne at Hengistbury Head which is known as the 'Long Groyne'. The beach in bournemouth is not man made, however the council are also keen to restock the sand on the beach which again comes under the Beach Management Scheme. Thousands of tonnes of sand is moved from one end of Bournemouth Beach to the other to guard against the effects coastal erossion.

We have links to the schedule of groyne replacement in our useful documents. 

Groyne Replacement Plans

What is a Groyne?

So what is a groyne, and how does it help the council at Bournemouth protect the coast? Groynes are man made barriers from the back of the beach and down to the sea. Bournemouth groynes are created to prevent the sand on the beaches being washed away with longshore drift. The groynes run perpendicular to the shore extending from the beach promenade into the ocean. Some of the groynes being visible from the beach, some of the groynes below the water line. The length, elevation and spacing between the groynes is determined by the local wave energy which is why they are not all the same distance apart as you walk down the promenade. Groynes which are too long or too high actually accelerate downdrift erosion, trapping too much sediment. So the length and height of the groyne are critical in performing their main function as efficiently as possible.

The groyne creates and maintains the beach in as wide an area as it can and acts as a physical barrier to prevent the sand moving in the direction of longshore drift.

 What are the goynes made of?

 Groynes along the coast in Bournemouth are typically made of a timber construction, the wood is usually a high quality hard wood. The Bournemouth timber groynes are constructed from high grade timber which is build in sections from horizontal planking and vertical piles.

The timber used is a combination of Greenheart timber, found in northeast South America and Ekki timber found in West Africa. One of the groynes has been constructed as a trial from FSC Basralocus with piles betyween 10 and 13 meters.

 How Do Groynes assist in prevention of coastal erosion?

Groynes were originally installed along the Bournemouth coastline in 1915. Groynes control beach material and prevent undermining of the promenade seawall. The groyne causes the waves to break earlier and dispense the majority of their stored energy preventing the large waves breaking directly along the beach or against the shoreline itself. This reduces the sediment carried up and down the beach.

Are The New Groynes in Bournemouth bending already?

As the Bournemouth Borough Council continues to replace the seafront groynes which protect the coastline there was concern raised when the newly installed groynes appeared to be bending. A BBC spokesman reassured those with concerns thtat 'the groynes are subject to some natural movement and that a slight bend in the groyne is nothing to worry about.' The natural movement is caused by the way in which the sand levels on the beach change with seasonal variations.

Are the Council Installing New Groynes as Part of the Beach Management Program?

The plans from the council are to replace 60 plus existing groynes including 30 groynes which span the seafront from Southbourne to Hengistbury Head, 30 Groynes along the seafront from Southbourne to Alum Chine. 60 plus groynes will be replaced and three additional groynes added between Boscombe Pier and Gordon's Corner.