Lymington Harbour habitat replenishment scheme
Topic of the practice
Habitat enhancement of intertidal areas for the purpose of mitigating impact to N2K habitat as a consequence of the construction of a breakwater.
Good Practice Information
The purpose was to undertake a habitat replenishment scheme on an area of degraded/eroded saltmarsh, using sediment dredged during the maintenance dredging activities at the harbour, aiming at raising the level of an area of intertidal mud within the tidal frame. This would provide a greater window for birds to use the area for feeding and providing the potential for saltmarsh plant colonisation.
To ensure that sediment was retained on the site, drainage channels were blocked using semi-permeable structures made of willow and straw. A discharge pen was also built to prevent the saltmarsh erosion during sediment discharge, along with flow retarding structures to slow the sediment and water flows across the site to promote pooling and sediment and to stimulate deposition of the sediment.
Evidence of success
Visits showed the discharge pen was successful in protecting the saltmarsh and dispersing sediment and water flowing out across the site. Re-using dredged sediment helps to retain sediment in the system. As for the recharge at Lymington, it also helped to enhance the quality of the habitat, which could provide greater feeding opportunities for birds and an opportunity for saltmarsh to colonise.
Contact details to obtain further information on the practice
East Sussex County Council
Annex completed on: 06-28-2012