Dynamique sédimentaire intertidale en baie du Mont-Saint-Michel entre évolution naturelle et aménagements

The Bay of Mont-Saint-Michel exhibits unique intertidal sediment dynamics shaped by exceptional tidal ranges (up to 14 meters) and vast intertidal zones, creating a rare megatidal hydro-sedimentary system. Research reveals that while the western bay's sediment dynamics are stable with minimal annual changes (<10 cm), wave action erodes coarse bioclastic sands, transporting them at rates of tens of meters per year to form discontinuous but stable shell bars along the shoreline. The eastern estuarine zone is characterized by channel migration influencing sandy intertidal morphology. Sediment accretion near Mont-Saint-Michel varies from 0.2 to 10 cm/year, depending on morpho-dynamic context, supporting regular mudflat deposition and salt marsh expansion at ~17 ha/year. The bay's long-term filling, driven by sea-level oscillations, has historically led to the gradual infilling of Dol Marsh and shoreline progradation. Human activities, including fixed fisheries, shellfish farming, polderization, and dike construction, have significantly altered these natural processes, with historical reconstructions providing insights into their impacts.

BONNOT-COURTOIS, C. (2012). Dynamique sédimentaire intertidale en baie du Mont-Saint-Michel entre évolution naturelle et aménagements. XIIèmes Journées, Cherbourg, 187–222. https://doi.org/10.5150/jngcgc.2012.021-b