Monitoring of fast moving landslides in the Pyrenees

(ENG) The paper presents the experience of two instrumented sites in the Pyrenees where debris flows and rock falls occur frequently. The first one is the debris-flow monitoring system in the Rebaixader catchment, Central Pyrenees, Spain, installed since summer 2009. It consists of sensors registering meteorological and infiltration data as well as geophones, radar, ultrasonic sensors and a video camera focusing on the detection and dynamics of the flows. 24 torrential flows (debris flows and debris floods) and also 5 block falls have been detected. The second site is a recently installed rockfall monitoring system at the Forat Negre couloir, in Andorra la Vella, Principality of Andorra. It consists of 5 geophones and a video camera. For the same area high resolution point clouds obtained by remote techniques such as digital photogrammetry and Terrestrial Laser Scanner additionally permit the assessment of rockfall volumes and geometry, overcoming access restrictions.