Coastal retreat: GIS-based mapping for sustainable urban planning in Villeneuve-lès-Maguelonne
About this good practice
The municipality of Villeneuve-lès-Maguelonne (VLM) faces significant environmental, socio-economic, and heritage-related challenges that need to be preserved. To better anticipate coastal retreat, it has developed prospective maps projecting shoreline evolution at 30- and 100-year horizons, helping guide future management and planning strategies.
This work follows state-recommended guidelines and applies a methodology based on multiple parameters:
• Retrospective analysis: Calculation of annual shoreline evolution trends using aerial and satellite imagery (1977-2020).
• Extreme event impact: Estimation of coastal retreat caused by storms, considering historical extreme events as a reference.
• Sea level rise projection: Modeling the long-term effects using Bruün’s rule.
This multi-factor approach combines GIS, remote sensing, and scientific modeling to provide a forward-looking assessment of coastal dynamics. As part of the Climate & Resilience Law, VLM plans to integrate these findings into future urban planning documents.
Local policymakers will use these maps to inform decision-making, while the scientific community and the Occitanie Coastal Observatory will leverage them to refine vulnerability assessments.
Resources needed
The study was led by Montpellier Métropole (1 full-time equivalent – FTE) and carried out by the SaVE association (2 FTEs), with 80% funding from the State’s Green Fund. The project involved remote sensing, GIS, and modeling tools, as well as expertise in geomatics and coastal dynamics.
Evidence of success
The study identified the most vulnerable areas along the VLM coastline and initiated discussions on short-term management actions, such as dune system restoration. The produced maps serve as a basis for integrating coastal retreat into the local urban planning framework and shaping long-term adaptation strategies.
Potential for learning or transfer
This practice is transferable to other low-lying, sandy coastal areas facing erosion and rising sea levels. The recommendation guide is replicable and can evolve based on feedback from pilot sites.
Key success factors include collaboration between local authorities, scientists, and state agencies, along with access to historical data and GIS tools. However, transferring this practice requires adaptation to local sedimentary dynamics and urban planning constraints.
While the results are not yet officially published, VLM’s experience could serve as an inspiration for other coastal municipalities.
Further information
Images
Documents
Recommandations-carte-locale-trait-de-cote_BRGM&Cerema_Aout-2022.pdf
srgitc_modifiee_par_decision_du_30mai2023_caa_toulouse-1.pdf
t3_annexe_rapport_recul_trait_cote_0.pdf
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Good practice owner
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