What coastline for the future in Seine-Maritime?

Drawing up a strategy for development schemes that meets the challenges of climate change and the choices of local players and residents

The Syndicat mixte du littoral Seine-Maritime, which is coordinating the development of the “Stratégie Littoral 76”, has chosen Artelia to support it in this process, carried out in consultation with the various local players. 

The main objective is to improve the management of natural risks, by anticipating the effects of climate change on this coastline with its complex morphology, which comprises 140 km of coastline between Le Havre and Tréport, and has many residents and infrastructures.


From a geomorphological point of view, the Seine-Maritime is characterised by the presence of valleys and valleuses (plateaux giving access to the sea) which cut into a coastline of high limestone cliffs. Its 140km of coastline is dissected by 9 rivers and includes around thirty beaches and access points to the sea. The region has over 270,000 people living in 39 municipalities, and welcomes around 2 million visitors every year. It also has some major infrastructure (5 ports, 2 nuclear power stations) and significant coastal development (12.5 km of dykes, 136 beach protection groynes, etc.).

Like many coastal areas, the Seine-Maritime region has been experiencing increasing marine submersion since the 1950s, and its coastline is retreating in many places. This evolution, which is going to increase under the effects of climate change, has convinced the authorities to adopt an adaptation strategy, which they have awarded to the Syndicat mixte du littoral de la Seine-Maritime. While reducing the area’s vulnerability to the risks of flooding and retreat of the coastline is a major concern, preserving natural environments, raising public awareness and changing uses are also key aspects of the planning process.

Artelia is supporting the Syndicat throughout the process, which must be carried out in a co-construction mode with players and citizens in order to enhance the risk culture and reach shared compromises and objectives. Our teams have already led several public meetings and more than twenty workshops are scheduled, notably on the effects of climate change. They have begun analysing the wide range of data available on coastal dynamics and land-use planning, while conducting targeted interviews with around forty key players on these subjects. The final phase will involve using this shared diagnosis to build a long-term vision of the area, proposing different scenarios for change and helping the Syndicat to identify and implement the most appropriate solutions for the situation and the expectations of the area’s players and citizens.