Real-time detection and management of rockfall hazards by ground-based Doppler radar

Rockfalls are ubiquitous products of landscape evolution in steep mountainous terrains. Among other effects, they pose a significant concern to the management of transportation corridors located on valley floors. Here, we describe the field application of a ground-based Doppler radar that performs real-time, long-range, wide-area detection and tracking of rockfalls and related slope hazards. We deployed the instrument at the Ruinon landslide, where accelerated deformation of upper chaotic debris has for several months promoted secondary mass wasting processes of extremely rapid velocity. In particular, large rolling boulders had the potential to propagate beyond the toe of the landslide and impact a road that connects important localities in the Italian Alps interiors. The Doppler radar was programmed to actuate a pair of traffic lights so that a predefined exclusion zone could instantly be enforced for approaching vehicles upon initial movement detection. We discuss the setup of the alarm system, the main observations collected during the monitoring campaign, and how this technique may enhance safety in areas critically exposed to rockfalls as well as our understanding of rockfall dynamics in general.