A new real-time debris flow and snow avalanche detection system based on optical fiber sensing

This paper presents a novel real-time detection and early warning system for debris flow and snow avalanches based on distributed optical fiber sensing called Optialp. The functioning principle of the system is based on detecting the vibrations and the impacts generated by the propagation of these phenomena in a spatially continuous way through the real-time analysis of the polarization variations along the optical fibers. A prototype of the system was extensively tested through an experimental laboratory setup reproducing a slope to scale. A series of tests were carried out emulating mass movements. Data recorded from all the tests were used to develop a new algorithm based on a threshold value and a moving average filter capable of distinguishing the signals related to the emulated mass movements from all the further noisy signals. The algorithm was integrated into a prototype of a fiber optic interrogator which performs the real-time analysis of the data acquired and can generate a warning signal whenever mass movements are detected. The results obtained at the laboratory scale have revealed that the technique could precisely, simply, and rather economically identify the polarimetric perturbations induced on the optical fibers by external forces. The laboratory results are promising and suggest that the optical fibers embedded into the ground along one or more sections of the channels where the debris flows or snow avalanches propagate can be used as a novel distributed detection and early warning system, improving the current technologies typically based on discrete monitoring points and sensors.