Dredging of Maritime Approach and Harbour Channels. Management of Dredged Sediments

Historically, waterway transport has been vital to domestic and international trade. It offers the most economical, most energy-efficient and least polluting form of freight transport of all.

Shipowners' objectives of improving the profitability of maritime transport and technical developments have led to the construction of ever larger, ever heavier ships, with ever deeper draughts, forcing ports to adapt and size their infrastructures (port access channels, berthing structures) to accommodate such vessels. Estuary ports have gradually given way to coastal ports, with shorter access channels that lend themselves more easily to deepening work.

For container transport, only a few major coastal ports have had to or been able to adapt their port infrastructure to accommodate the latest-generation container ships.

Port 2000 in Le Havre was commissioned in 2006, and the quay length was increased by 2.1 km in 2010, or for ships with a draught of 16.00 m, or even more (up to 18.00 m).

Under pressure from the new modes of transport mentioned above, most of the major ports along the coast have been forced to implement projects to widen and develop access channels, basins and avoidance zones, making massive use of various dredging methods, which involve digging, transporting, emptying or depositing the dredged sediments on an appropriate site.

To meet the challenge of massively increasing maritime traffic, we need to reduce the time containers and passengers take to pass through the port, by simultaneously organizing appropriate hinterland services: firstly, river services, where they exist for estuary back-ports, and rail services, followed by fluid road services. By way of illustration, a very small percentage of containers unloaded at the port of Le Havre for inland France are redistributed by waterway and rail, whereas over 80% of these containers are re-routed by road.

We can't accept that ports are just the gateway to a transport chain whose other links are neglected. This transport chain, and in particular maritime and river transport, deserves to be nurtured, enhanced and maintained from end to end.

However, in parallel with the implementation of investment projects, tides and floods naturally and inexorably bring in marine and river sediments, forcing ports to carry out dredging campaigns to maintain navigable accesses, in order to preserve the seabed required for navigation and to ensure the safe berthing of ships.

Nowadays, three categories of players are involved: citizens (local residents, marine professionals), politicians and engineers.

Since the 1990s, new environmental and quality-of-life...