Moving Sediments In Natural Systems
In this paper CEDA Environment Commission presents its consolidated view on what environmentally responsible dredging really means at the beginning of the 21st century. The paper is intended for use by CEDA members and others in the maritime community, including government agencies, regulators, decision-makers, dredging companies, consultants, stakeholders and the general public
Dredging is a necessary activity in civilisation’s development – in its simplest form it consists of the excavation of material from a sea, river or lake bed and the relocation of that material elsewhere.
It’s commonly used to improve the navigable depths in ports, harbours and shipping channels, as a tool in water and flood management, for the creation of new lands and natural habitats and to win minerals from underwater deposits.
Dredging is therefore of crucial importance for sustainable development of natural resources, economic values and human quality of life.
Environmental Care
By its very nature the act of dredging will change the environment. Dredging projects are executed to alter water systems, which inevitably has an effect on the aquatic ecosystem. When planning dredging activities, it’s therefore common practice to determine the positive and negative effects on the aquatic environment and the duration of such effects.
The marine and freshwater environment is a complex combination of natural features and phenomena, supporting a diverse – but largely concealed – aquatic ecosystem. Because of this complexity, predicting the effects of human-induced interventions and short-term operations can be extremely difficult. Comprehensive and detailed investigations of environmental characteristics are commonly a prerequisite for any planned dredging campaign.
That complexity also means each dredging project is unique. The local, natural conditions have to be taken into account and the effects should be evaluated in relation to natural dynamics and fluctuations. These include hydrodynamics (including storms), ecology and sediment quality. In addition, legislative, socio-economic and other functions – such as shipping and fisheries – should be carefully considered.
Evaluation of environmental impacts should examine both the short- and long-term effects, as well as the sustainability of the altered environment. If necessary, appropriate control measures should be taken to avoid or reduce unwanted impacts and to meet specific environmental objectives.
The dredging industry has a large ...