Poole Bay Nearshore Beach Replenishment Trial 2015
Borough of Poole has been awarded £260,000 funding to trial a beach replenishment
process that could make future projects more economically and environmentally sustainable.
The trial, endorsed by the Environment Agency both locally and nationally, and supported
by SCOPAC (Standing Conference on Problems Associated with the Coastline) involves
Borough of Poole working in partnership with Poole Harbour Commissioners, the Environment
Agency, Southampton University and the Channel Coast Observatory.
Funding has been provided by:
Environment Agency: £130,000 for the placing of sand on the seabed; the Marine Management
Organisation (MMO) has granted a licence to allow this operation.
Environment Agency Research & Development Fund: £115,000 for monitoring
SCOPAC: a further £15,000 towards monitoring costs
Beach levels will be surveyed before, during and after the trials;
Multibeam swath bathymetry surveys before, during and after the project will generate
3D images of the seabed and demonstrate how the beach material has moved;
An Acoustic Doppler Current Profiler (ADCP) will measure the speed and direction
of water currents and turbidity;
Wave height, direction and spread and sea temperature will be monitored at the Boscombe
wave buoy by the Channel Coast Observatory [real-time data available here]
Silt Traps (vertical tubes measuring 40cm x 8cm) will monitor changes outside the
immediate area of works. Southampton University have used silt traps in the bay previously
whilst carrying out marine habitat surveys during Channel deepening projects, and
will return to instal them at 3 sites across the study area, to be replaced and measured
on a monthly basis; sites are shown on the detail map (right)
Luminescent Sediment Tracers (fluorescent painted sand) will be used to track movement
of sand over a period of months.
The success of the trial will be measured by:
Having little to no effect on the Poole Rocks MCZ (Marine Conservation Zone, designated
November 2013 and marked in green on the detail map, right)
Movement of the material towards the foreshore
Reduction in beach erosion, and
The economic viability of near-shore renourishment.
Conventional beach renourishment, pumping sand ashore and spreading it using land-based
plant, is not economical for small scale projects due to high mobilisation costs
(estimated to be in the order of £300,000)
The trial site has been selected owing to its position at the up-drift end of the
bay; sand can be driven onto the beach by wave action then moved around by littoral
drift (breaking waves and longshore currents), thus making best use of the sand as
it moves along the foreshore. The site selection also means that dredgers can operate
without the restriction of tidal working.