Completed Project

Hengistbury Head Long Groyne works 2021-2024

A Poole Bay Beach Management Scheme project

As part of a 17-year Beach Management Scheme, the Long Groyne was repaired & upgraded between April – October 2024

Lead Authority

BCP Council

Working with

VBA Joint Venture

Project start date

22 November 2021

Project completed

October 2024

Page last updated

21 August 2025

The completed Long Groyne

Long Groyne completed

The upgrade of the Long Groyne was completed in October 2024 and the surrounding beach was restored.

Our contractors worked with the tides around the clock, placing a total of 33,500 tonnes of rock that arrived by sea from France and Norway. A host of environmental enhancements were incorporated into the design to provide important new marine habitat.

To the west of the Long Groyne towards Solent Beach Car Park we made efficient use of the machinery and rock on site to replace and strengthen two life-expired timber groynes as part of our ongoing Asset Maintenance programme in October/November.

Surveying intertidal cubes at Hengistbury Head © A Hall Marine

The Long Groyne – One Year On

By Kay Kitcatt | 21 August 2025

Since works to the Hengistbury Head Long Groyne were completed in October 2024, we have continued our regular beach monitoring, surveys have been carried out on the marine habitat structures, and the project has been nominated for a People's Choice award

Our project update ...

Background to the works

The Long Groyne at Hengistbury Head plays a critical role in reducing coastal erosion in Poole Bay and is a stabilising feature for Christchurch Bay. However, during storm events the original structure was regularly submerged meaning it was unable to continue to perform effectively, particularly with the additional threat of sea level rise.

A detailed inspection of the structure in 2019 revealed the groyne to be in very poor condition. Subsequent ground investigations and underwater surveys through 2021 & 2022 helped us prepare for the significant works required to protect the coastline from sea level rise over the next 100 years.

Planning permission was granted for the project in September 2023. On-site preparations started 11 March 2024, with works licensed to take place from April-October.

The original concrete long groyne at Hengistbury Head

The original long groyne Hengistbury Head

The Long Groyne project video

From rock deliveries in April to installing artificial marine habitat enhancements, and completion of the repaired & upgraded Long Groyne in October 2024; our video condenses project progress into 3 minutes.

The full Countryfile ‘Hengistbury Head’ episode aired 14 July 2024, but was removed from BBC iPlayer 12 months later

Countryfile at Hengistbury Head, July 2024

Sean Fletcher from BBC Countryfile meets Matt Hosey, Head of Service at South West Flood & Coastal and the team reconstructing the Long Groyne at Hengistbury Head to find out how BCP are defending the coast from flooding and erosion.

Sean jumps into a giant dumper truck and drives out to the groyne with Site Manager Maz Tamimi, then joins Dr Alice Hall, Marine Biologist, on the beach to learn how marine life will be offered new, artificial reefs to colonise around the new groyne.

Deconstructing the original groyne

The original concrete long groyne at Hengistbury Head

The old groyne is dismantled in sections

The concrete material is crushed to form the core of the new long groyne

Deconstruction of the original groyne is complete (July)

Construction

Work to dismantle the original concrete groyne was carried out in short sections at a time to ensure beach material remained in place
Concrete from the original structure, along with the old rock armour, has been used to form a new core base
New rock armour has been placed on top in the same footprint as the original groyne.

Cross section of the upgraded design

The upgraded long groyne design:

Maintains the same alignment and length as the original groyne (approximately 150 metres).
Is 1.5 metres taller along its crest than the original groyne to allow for increased storm events and predicted sea level rise.
Is wider than the original groyne to provide additional stability in this exposed location.
Is covered entirely in rock, using a natural quarry stone (armour) from France & Norway, chosen for its durability.
Uses larger rocks (6 – 10 tonnes) than the original, to cope with the exposed location of the structure and the expected wave conditions.
Re-uses material from the original structure wherever possible to avoid having to send material to landfill, and to minimise the amount to new rock required.
Floating groyne markers have been placed at the sea end to aid navigation.

Project aims explained by Richard Slee, ITV News

Video courtesy ITV News Meridian, 23 May 2024

Why the works were needed

If we had done nothing to repair or upgrade the long groyne, then;

The rate of erosion would rapidly increase at Hengistbury Head, resulting in the loss of beach followed by erosion of the cliffs;
The long-term loss of land would extend across Purbeck, Bournemouth, Christchurch, Poole and the New Forest, including damage to infrastructure and thousands of properties;
Mudeford Sandbank could be breached, creating further inlets to Christchurch Harbour;
Both Poole Bay and Christchurch Bay would weaken and eventually become one bay.

New marine habitat

A number of environmental enhancements have been incorporated into the design of the upgraded long groyne, promoting biodiversity by creating complex habitats for fish, invertebrates, and algae.

Granite rock pools

Shallow rock pools have been ground into several of the granite rocks that make up the Long Groyne, providing a basin that is flushed by the sea on high tide and exposed at low tide.

Limestone rock pools

Rock pools have also been ground into limestone reclaimed from the original Long Groyne and placed all around the marine habitat units above. Being quite porous, and already acclimatised to the marine environment, limestone is ideal for promoting further marine growth.

Natterjack Toad conservation

We are also supporting conservation of the rare and endangered Natterjack Toad within Hengistbury Head Nature Reserve, through the funding of two specialised breeding ponds.

Placing the MOSES reef units in the lee of the groyne

About the Long Groyne

Construction of the original Hengistbury Head Long Groyne was completed in 1939. Its location has enabled beach material to accumulate around the headland, reducing tidal erosion of the cliff face.

From the 1980s to the early 2000s rock armour was added to the concrete groyne structure, and additional groynes were constructed at Mudeford Sandbank, which have further helped stabilise the Sandbank in its current position.

Constructing the long groyne 1937-39, photo gallery

26th January 1937

8th July 1937

23rd August 1937

21st September 1937

20th October 1937

19th November 1937

16th March 1938

14th April 1938

15th May 1938

2nd June 1938

13th August 1938

10th October 1938

24th October 1938

1st June 1939

1st June 1939

Hengistbury Head Long Groyne, November 1937

This photo was taken 19th November 1937, during construction of the long groyne; the southern-most tip of the headland shows the threat of erosion to the cliff face.

Hengistbury Head Long Groyne, June 1939

Photo taken 1st June 1939; following its construction, beach material travelling from west to east along the shoreline quickly accumulated, providing some protection to the cliff.

The purpose of the long groyne

The Hengistbury Head groyne was constructed between 1937–1939 to protect the headland. It is now well recognised as an “anchor point” that is critical to stabilising and controlling coastal erosion in both Poole Bay and Christchurch Bay. Along with the beach and other shoreline structures, the long groyne helps to protect local communities and infrastructure.

Without it, beach material would rapidly wash away (estimated with in a year), and the cliffs could start to erode again. This would eventually progress to the sea breaching into Christchurch Harbour via locations at Double Dykes and Mudeford Sandbank. The impacts could extend to the Purbecks and New Forest.

The current national policy for most of this populated coastal frontage is ‘hold the line’. This means that existing coastal defences should be maintained, upgraded or replaced in their current position, where funding permits, to reduce the risk of coastal flooding and erosion.

More about coastal defence policies at Poole & Christchurch Bays Shoreline Management Plan

The angle of the long groyne

In recent years, there have been proposals to alter the angle of the groyne, including potentially creating new surfing opportunities. The proposal has been reported on in the local media although it cannot be supported for important reasons, which are summarised as follows:

It is crucial that the long groyne continues in its main function to limit long term coastal erosion in Poole Bay and Christchurch Bay.
Coast protection is manageable under its existing configuration as set out in strategic policy (i.e. Poole & Christchurch Bays SMP) which is economically justified*.
For the last 50+ years the long groyne has profoundly influenced the transit and deposition of beach material from Poole Bay into Christchurch Bay. The volume of beach material from Avon Beach and Highcliffe has then been managed by local beach recycling, when required – for example Christchurch Beach Recycling and Rock Groyne Repairs, spring 2021.
A change in the angle of the groyne would generate new and unknown hydrodynamics that would affect the entrance to Christchurch Harbour.
Modelling and data underlines layout changes as being high-risk with high uncertainty (in terms of being able to predict long term implications). Layout changes could trigger wide-reaching impacts on interlinked coastal protection assets across Dorset and into Hampshire.
Hengistbury Head and its surrounding areas have many environmental designations (both national and international) which must be carefully adhered to. Additionally, the area falls into a Coastal Nature Park, as supported by other BCP Council strategies.
The legacy council in Bournemouth invested in Boscombe as a surf-based tourism destination. It is supported by local facilities including year-round lifeguard cover, car-parking, toilets, showers, food outlets and accommodation. Hengistbury Head does not have the same offer and is in a more remote, potentially more dangerous location; exposed to swell waves and ebb currents from the Harbour.

* The Environment Agency is responsible for the approval and allocation of all coastal capital funding in England. Capital investment schemes go through an appraisal & approval process both on technical and financial grounds to secure grant funding. To be considered for funding schemes should be in line with the strategic direction set out in the SMP or strategy; they must also contribute to outcome measures and be on the sanctioned list.

Long groyne investigations 2019-2022

Several voids were discovered in the foundations of the original structure during a detailed inspection in 2019, with an associated risk of localised collapse; public access was prohibited for safety reasons pending further investigation.

Following initial ground investigations carried out Nov-Dec 2021, works continued during August 2022 with further investigations to help prepare for the upgrade of the entire long groyne structure.

Underwater surveys mapped out the depth and land beneath the surface while borehole investigations revealed the composition of the ground below the structure. Boreholes up to 20m in depth were collected from both land and sea using a rotary drilling rig (on land) and a sea-based jack-up barge, as shown.

All data collected will help refine the most efficient and effective design for the new groyne structure to ensure the continued stability of the coastline, while protecting it from sea level rise over the next 100 years.