Brittany facing the challenge of coastal erosion.
The Breton regional council adopted a guidance document on Friday to adapt the coastal sectors to this phenomenon while 25,000 inhabitants live in Saint-Malo below sea level and nearly 130,000 in total are potentially threatened.
Concretely, the main objective of the document, the first adopted by a region, is to help coastal communities and municipalities to take into account in their local development and town planning policies the most recent scientific studies carried out on the sea level rise and the risk of submersion.
The search for “local solutions”
Voluntary municipalities (currently 93) are invited to produce erosion maps at 30 years and 100 years before three years, then to integrate these results into their Local Urban Plan (PLU) with “very restrictive” regulations.
While promoting consultation with residents, they could also “pre-empt properties in the erosion zone in 30 years”.
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“The region provides engineering and skills assistance, and we ask the municipalities to look for local solutions”, adapted to the configuration of the premises, explains Daniel Cueff, vice-president of Sea and Coast at the regional council.
Of great diversity (48% rocky cliffs but 24% sandy coasts), these 4,900 km of coastline constitute “a specific Breton lace, more complex to understand, observe and manage” than in other metropolitan regions. .
This explains the diversity of solutions envisaged according to the territories and the challenges, particularly economic, presented by the different sites: “protect yourself”, “adapt”, “renature and, if necessary, relocate” or even “let nature take its course” , like letting the sea return to agricultural polders.
Possible “human losses”
The document recalls that “in 300 years, the tide gauge at the port of Brest has shown that the sea level has increased by 30 cm (i.e. one mm/year on average)”.
With global warming of +3°C at the end of the century, the rise in sea levels could reach one meter over the same period.
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“More than 80 buildings protected as historic monuments are threatened by rising sea levels in Brittany” but also 41,000 homes, 42,000 jobs and more than 100,000 ha of agricultural land, or 4.3% of the total, notes in particular the adopted document.
The latter highlights the case of the seaside town of Carnac (Morbihan), which has more than 70% second homes and where “2,000 buildings are threatened by erosion and/or marine submersion by 2,100 ".
The document warns of possible “human losses” and “increasing damage and economic and social costs over time”.