CURRENT PROJECTS

Poole Bay Beach Management Scheme

2015-2032

A 17-year plan to protect the coastal frontages of Poole and Bournemouth.

LEAD AUTHORITY

BCP Council

WORKING WITH

Various Contractors

START DATE

October 2015

END DATE

Winter 2032

Replacing wooden groynes 2015/16

Project Background

Poole Bay stretches from Sandbanks in the west to Hengistbury Head in the east. Over the last 100 years coastal defence works have included the building of seawalls, construction of a groyne field and the creation and maintenance of an artificially widened beach along this length of coast. In 2011, the Poole and Christchurch Bays Shoreline Management Plan (SMP) set policies to manage the risk of coastal erosion along Poole Bay, through a mostly ‘Hold the Line’ approach over the next 100 years, meaning coastal defences should be maintained and upgraded or replaced in their current position where funding permits. The SMP policy is achieved using a combination of beach replenishment and groynes.

Why beach replenishment?

In Poole Bay the physical protection of the coastline with a sea wall and promenade limits the natural erosion of cliffs which would otherwise top-up beach levels. Cyclic beach replenishment schemes are therefore required to maintain a frontline defence and this requires the use of non-native material. Studies have shown approximately 70,000m³ of sand is lost from the Poole Bay frontage each year. The beach material is transported by wave action and generally moves eastwards towards Hengistbury Head by a process called longshore (or littoral) drift. Eventually sediment may be transported and deposited further offshore in Poole Bay or into Christchurch Bay. 

Sediment Transport (longshore drift) in Poole & Christchurch Bays

Source: SCOPAC Sediment Transport Study 2012, Poole Harbour Entrance to Hengistbury Head. Available at www.scopac.org.uk/sts/poole-bay.html

Source: SCOPAC Sediment Transport Study 2012, Hengistbury Head to Hurst Spit. Available at www.scopac.org.uk/sts/christchurch-bay.html

Why groynes?

As part of the coast protection measures in Poole Bay, groynes are strategically placed to retain the beach material moved by longshore drift. Beaches at Poole and Bournemouth include a variety of groyne types including rock, timber and hybrid structures (constructed from timber with rock on the outer ends) – the former of which have a longer life-span. The combination of groynes with periodic beach replenishment allows the sea walls and cliffs to be better protected.

The current Beach Management Scheme is replacing the life-expired timber groynes along the Bournemouth section of Poole Bay which have a life-span of approximately 25 years.

Project Overview

Beach Management in Poole Bay is designed to provide protection to a significant number of residential and commercial properties for the next 100 years. Without it, properties, highways and supporting infrastructure would be lost to coastal erosion.

The Poole Bay Beach Management Scheme will take place between 2015-2032, and will be carried out in three distinct phases. It is estimated the entire scheme will cost in the region of £50 million, with the majority funded by the Environment Agency.

Overall the aims are to: 

  • replace Bournemouth’s existing 53 timber groynes, in multiple short phases (based on the life-expiry dates of the structures);
  • construct an additional three new timber groynes;
  • reconstruct the Hengistbury Head Long Groyne;
  • complete three beach replenishments, approximately once every five years.

Project Progress

Phases 2 & 3 (2020/21 – 2032)

In May 2020, BCP Council received official confirmation from the Environment Agency that it had been awarded £33 million of combined government Flood Defence Grant in Aid (FDGiA) and Local Levy. A capital contribution of £3.3 million by BCP Council was approved in October 2019.

Starting winter 2020, this phase will:

  • Replace the remaining 23 timber groynes plus three new groynes, located along the seafront from Southbourne to Alum Chine;
  • Provide a further two beach replenishment operations (locations to be determined nearer the time);
  • Repair and upgrade Hengistbury Head Long Groyne to ensure the continuation of coast protection for Poole Bay and Christchurch Harbour.

Phase 1 (2015 – 2020)

Hengistbury Head Long Groyne

Status: Exploratory work completed 2019

  • The long groyne was constructed from 1937-1939
  • A intrusive condition survey was carried out from May 2019
  • A number of voids in the underlying foundations have been found and there is a risk of localised failure
  • For safety reasons the groyne was closed to the public in August 2019
  • Reconstruction is planned to take place in 2020/2021

Bournemouth Beach Groyne Replacement / Construction, 2017-2019

Status: complete

  • Replace 12 timber groynes at Southbourne, from St Catherine’s Path to the eastern end of the promenade
  • Delivered over a two year period; six groynes in each year
  • Contractor: Suttle Projects

Bournemouth Beach Timber Groyne Replacement, winter 2016/17

Status: complete

  • Replace 8 timber groynes eastwards from Fisherman’s Walk to Gordon’s Corner
  • Contractor: Mackley

Bournemouth Beach Replenishment, spring 2016

Status: complete

  • 355,500m³ of dredged material was distributed on the beach between Bournemouth Pier and Solent Beach, Southbourne
  • Contractor: Van Oord
  • Project cost: £3.9m

Bournemouth Beach Timber Groyne Replacement, winter 2015/16

Status: complete

  • The first 10 of a planned 56 timber groynes have been replaced
  • Groynes range from the east of Boscombe Pier by Honeycomb Chine to Fisherman’s Walk, near the zig-zag path
  • Contractor: Mackley
  • Project cost: £3.6m

Assessing the performance of timber groynes at Bournemouth Beach, 2015-2017

A 29 year field-test of five different species

Status: complete

As part of the groyne renewal programme at Bournemouth beach, a study was made into the performance of five ‘experimental’ groynes that had been built between 1985-1987 in order to evaluate the performance of different timber types in the field: