Pumping drinking water from wells miles inland is causing a famous French coastline to physically collapse into the ocean.
April 29, 2026
Original Paper
Why the Cap-Ferret sand spit is collapsing
EarthArXiv · 10.31223/X52V11
The Takeaway
Most coastal erosion is blamed on rising sea levels or heavy waves hitting the shore. This research found that the Cap-Ferret sand spit is actually falling apart because the groundwater beneath it is being drained. When people pump water for nearby towns, the pressure in the aquifer drops and the sand loses its structural support. This creates a hidden form of erosion that traditional oceanographic surveys completely missed. It proves that our demand for fresh water can destroy local geography in ways we never anticipated.
From the abstract
The Cap-Ferret sand spit (SW France) exhibits a pattern of coastal instability that combines chronic shoreline retreat (8.7 m·yr⁻¹ at the tip, Robinet et al. 2025), sudden vertical collapses of emplaced structures (WW2 blockhaus 2024, 2026; oyster-farm sector 1936, 1977; Hortense promenade 1999, 2000, 2014, 2019), and progressive deepening of submarine pits (Hortense-Pointe depression volume nearly doubled between 2005 and 2015; BRGM 2019). We show that these three signatures cannot be simultane