Dredging is the process of removing material from beneath the water surface and can be carried out wherever there is sufficient water depth to allow a dredger to operate. Dredging can be classified into two types: 'maintenance dredging', where existing channels are maintained at a specified depth such as navigational channels and berths; and 'capital dredging', which involves new works to deepen existing channels or to create new channels or deep areas for newly constructed berths.

The creation of artificial channels may have severe implications on the coastal and estuarine environment by modifying tidal flow, ebb and flood tide directions, the tidal prism, and the intertidal profile. Similarly, dredging causes the suspension of large amounts of sediment, which reduce the clarity of the water body and may have implications for the benthos in the immediate and surrounding vicinity.

Licences for dredging and the disposal of material arising from maintenance dredging are obtained from DEFRA after consideration of the proposed disposal area. In recent years, all applicants for sea disposal licences for dredged material in the UK have been required to consider whether the material can be managed in such a way to derive environmental or other benefits or the potential for beneficial use of the material.

If suitably pollutant free, the dredged material may be utilised elsewhere and dredged material from ports and harbours have been put to a range of beneficial uses, including construction, agricultural and environmental uses. It may be used for habitat recreation, to replenish and build up beaches, or offshore bars for coastal defence purposes. However, whilst intertidal recharge schemes can provide long-term benefits of environmental enhancement and protection, the act of placing material over existing intertidal habitats has the potential to cause the same short-term impacts of any disposal operation, generally associated with smothering and increased suspended solids.

Find below links to government and regulatory organisation sites which provide information on the economic effects of dredging.

Associated British Ports (ABP)
Central Dredging Association (CEDA)
Centre for Environment, Fisheries & Aquaculture Science (CEFAS)
Department for Environment, Food and Rural Affairs (DEFRA)
OSPAR
UK Marine SACs Project

Associated British Ports (ABP)

ABP - ABP is the Statutory Harbour Authority (SHA) for most of our ports and, therefore, responsible for conservancy in the areas under our control, which includes the maintenance of safe navigation. Link to ABP dredging.

Central Dredging Association (CEDA)

CEDA - Homepage for the Central Dredging Association (CEDA). Link to CEDA.

Centre for Environment, Fisheries & Aquaculture Science (CEFAS)

DECODE - Determination of Ecological Consequences of Dredged-material Emplacement (DECODE) umbrella group. Link to DECODE.

Department for Environment, Food and Rural Affairs (DEFRA)

Economic Evaluation of Disposal of Dredged Material at Sea. DEFRA (previously MAFF) report concerning "Economic Evaluation of MAFF's Policy Relating to the Disposal of Dredged Waste at Sea", prepared in association with ABP Research & Consultancy Ltd., May 1999. Link to report.

OSPAR

OSPAR - OSPAR guidelines for the management of dredged materials. Link to guidelines.

UK Marine SACs Project

Regulations governing Dredging - Information concerning existing regulations for dredging and disposal. Link to regulations.

Environmental Impacts of Dredging - Environmental impacts of maintenance dredging and disposal. Link to EIA.

Managing Potential Impacts of Dredging - Means of avoiding, minimising and addressing the potential impacts of maintenance dredging and promoting benefits. Link to information.

Further information on dredging is provided under the following general topics:

Environment
Erosion & Flooding