Session 3

Coastline evolution and submersion of coastal territories

As in many areas of the world, coasts of Normandy are subject to a strong retreat of the dune and cliff areas, of dune ridge ruptures which bring into the sea continental sediments participating in the sedimentary movements also generated by the port activities. The two major harbours: Rouen and Le Havre, both located in the Channel, discharge 7 million cubic metres of sediment into the sea per year. The effects of port dredging and dredge deposits on coastal marine ecosystems will be discussed, as deposits are generally made in shallow coastal marine areas.

In a context of climate change and sea level rise, the hazards of submersion of coastal territories will also be addressed with a historical perspective.
The restoration of marine environments or the increase of their productivity via reef installations or compensation for the decrease in natural recruitment are also discussed.

Key words: Coastal erosion with historical perspective, littoralisation, sedimentary changes, risks of coastal submersion, evolution of benthic habitats, effects of dredging and clapage on biotopes, reclamation of sediments, social and economic impacts.