Hendaye, monitoring coastal erosion in high risk areas

The coastal area is subject to severe erosion and the retreat of the land can be dangerous in some cases. The Corniche road (D912), which connects Hendaye with Saint Jean de Luz, runs along the cliff. This road, which is very popular with tourists, is prone to landslides due to the geology (clay and flysch layers with an inclination parallel to the slope). The activity of the sea causes landslides, which can endanger the users of the road.

Monitoring

In cooperation with the company Geotec, a three-dimensional monitoring system and alarm system for the critical areas was installed. This provides the departmental authorities with real-time information on the condition of the road and enables them to trigger a road closure.

The instrumentation

The instrumentation consists of :

Two vertical inclinometer chains, depth 28 m and 37 m, measuring points every 50 cm
Two horizontal inclinometer chains, length 20 m, measuring points every 100 cm
Two borehole extensometers coupled to the horizontal inclinometer chains to measure lateral displacements.
Two surface fissurometers to track the surface movements of the benches
An autonomous data acquisition system with automatic data transmission for visualisation.