Past ProjectsBeach Replenishment Scheme 2005-2007
During the winter of 2005/2006 approximately 1.16 million m³ (1.74 million tonnes) of sand dredged from Poole Harbour channels and approaches was used to replenish beaches at Swanage, Poole and Bournemouth to protect them from erosion.
Dredgers pumped sand ashore 24 hours a day, 7 days a week, including Christmas and the New Year.
- The contractors arrived on 22nd November 2005, and the beach at Swanage was replenished first;
- Work at Poole started in December and was completed on 16th January 2006
- Work at Bournemouth started 19th January and was completed 18th March 2006. These works formed part of the wider Bournemouth ‘Beach Improvement Scheme’ (BIS) and was known as BIS4.1; beaches were replenished between Hengistbury Head and Boscombe.
A second Bournemouth contract was undertaken over winter 2006/2007 (BIS4.2), which replenished beaches between Boscombe Pier and the boundary with Poole.
The Need for Beach Replenishment
The standard of flood and coast protection at Poole Bay and Swanage depends mainly on the level and width of its beaches. Construction of seawalls and promenades over the course of the last century (1907-1970) put a stop to the natural supply of beach material from cliff erosion and it is necessary to occasionally replace beach material lost to longshore transport to the east, driven by wind and waves.
In the 30 years between 1970-2000 almost 2 million m³ of sand was used to replenish the beaches at Bournemouth and Poole. Since the predominant direction of longshore transport at Poole Bay is from west to east, new sand gradually feeds the beaches at Southbourne and Hengistbury Head to the east, and beyond into Christchurch Bay.
The on-going need for beach replenishment was identified in the Poole and Christchurch Bays Shoreline Management Plan 1999, and a subsequent report by Halcrow (2004) suggests that a further 3 million m³ will be required over the next 50 years in order to maintain protective beach levels and widths.
Availability of Sand
Purchasing and transporting sand from commercial sources (from licensed dredging sites south of the Isle of Wight or at the Thames Estuary) can be very expensive. So when an opportunity arises to utilise sand from local dredging operations it saves Defra – and consequently the British taxpayer – a considerable sum of money.
In 2005 Poole Harbour Commissioners (PHC) were due to dredge the harbour channels and approaches in order to increase depth from 6m to 7.5m below Chart Datum. It was also necessary to widen the Middle Ship Channel to 100m. Primarily, the deeper approach channel was required to meet the needs of modern ferries, the majority of which now have a minimum draft of over 6.5 metres, thereby securing the long-term viability of the Port
PHC dredged 2 million m³ of material from Poole Harbour channels and approaches, of which about 1.1 million m³ was suitable for beach replenishment. The remainder of the material (silts and clays) were disposed of under licence at an offshore disposal ground located off Swanage. PHC have utilised this site for the disposal of dredged material from Poole Harbour for more than 50 years.
The 1.1 million m³ of suitable material was distributed (approximately) as follows:
- Swanage beach – 90,000 m³
- Poole beaches between Shore Road and Branksome Dene Chine – 450,000 m³
- Bournemouth beaches between Boscombe Pier and Double Dykes – 600,000 m³
Poole Harbour is internationally recognised as a sensitive environment in terms of wildlife, geology and landscape. It is also important for recreational boating and supports a significant fishing industry.
In view of this, and in accordance with the Harbour Works Regulations 1999, a full Environmental Impact Assessment (EIA) was carried out by Posford Haskoning on behalf of Poole Harbour Commissioners and the local authorities. The EIA study and other extensive assessments of the likely effects of the channel deepening on, for instance, habitats, archaeology and water quality, resulted in one of the most significant investigations ever undertaken into the morphology of Poole Harbour.