The Coselmar project website makes available a tool for diagnosing the vulnerability of residential housing to the risk of marine submersion. This work builds on the observations drawn from the Xynthia storm, namely that all deaths occurred inside residential buildings. Using the work conducted by Freddy Vinet et al. on the location and layout of buildings where deaths had been recorded, the project leaders proposed an index allowing the identification of other sites with similar patterns. This index focuses on the scale of the building and is based on four criteria: a. potential water level, b. proximity to a protection facility, c. architectural type, d. distance to a shelter zone. The result is a map distinguishing “safe” buildings from those where casualties could occur in the event of a marine submersion due to their configuration and location. 

Based on these results, the research team carried out a cost-efficiency analysis. On the website, it is possible to test the impact of adaptation strategies on the buildings’ vulnerability (a. protection, b. relocation, c. accommodation of buildings, d. information and preventive evacuation). Given the cost of each of the measures and the vulnerability with or without measures, it is possible to calculate a cost-efficiency ratio for each strategy and thus, highlight their comparative interest. 

This work was carried out in seven municipalities along the French Atlantic coast, three of which had been directly affected by Xynthia, and four on the island of Noirmoutier where – as a starting point – an analogous vulnerability was assumed. Finally, the town of La Guérinière displayed the highest degree of similarity with the areas most affected by the marine submersion of 2010.

The website provides users with a methodology for diagnosing the vulnerability of residential properties to the risk of marine submersion and allows an economic analysis (cost-effectiveness analysis) of the different possible strategies for reducing vulnerability (a. protection, b. relocation, c. accommodation of buildings, d. information and preventive evacuation). 

The website should allow interested users to appropriate a scientific program’s research results, to understand vulnerability mechanisms and establish an inventory of the different actions that can be taken to limit this situation while underlining their benefits and drawbacks. Therefore, it enables the sharing and discussion of adaptation strategies in the event of rising sea levels and the risk of marine submersion in the municipality of La Guérinière.