Experiences from site-specific landslide early warning systems

C Michoud,M.-H Derron,M Jaboyedoff,S Bazin,L H Blikra

doi:10.5194/nhess-13-2659-2013

Abstract

Abstract. Landslide early warning systems (EWSs) have to be implemented in areas with large risk for populations or infrastructures when classical structural remediation measures cannot be set up. This paper aims to gather experiences of existing landslide EWSs, with a special focus on practical requirements (e.g., alarm threshold values have to take into account the smallest detectable signal levels of deployed sensors before being established) and specific issues when dealing with system implementations. Within the framework of the SafeLand European project, a questionnaire was sent to about one-hundred institutions in charge of landslide management. Finally, we interpreted answers from experts belonging to 14 operational units related to 23 monitored landslides. Although no standard requirements exist for designing and operating EWSs, this review highlights some key elements, such as the importance of pre-investigation work, the redundancy and robustness of monitoring systems, the establishment of different scenarios adapted to gradual increasing of alert levels, and the necessity of confidence and trust between local populations and scientists. Moreover, it also confirms the need to improve our capabilities for failure forecasting, monitoring techniques and integration of water processes into landslide conceptual models.

Highlights

Landslides are frequent phenomena in many natural environments, and remediation measures ought to be implemented in areas with high risk due to the presence of populations or infrastructures
A proper measure is to reduce the number of exposed people by implementing reliable landslide early warning systems (EWSs) that are capable of alerting and evacuating populations based on the monitoring of stability conditions of the landslide
EWSs are defined by the United Nations as “the set of capacities needed to generate and disseminate timely and meaningful warning information to enable individuals, communities and organizations threatened by a hazard to prepare and to act appropriately and in sufficient time to reduce the possibility of harm or loss” (UNISDR, 2009)

Summary

Introduction

Landslides are frequent phenomena in many natural environments, and remediation measures ought to be implemented in areas with high risk due to the presence of populations or infrastructures. Structural remediation measures have been extensively used for reducing and even eliminating the hazard (Piteau and Peckover, 1978; Holtz and Schuster, 1996; Wyllie and Mah, 2004; Cornforth, 2005; Vaciago et al, 2011). Classical countermeasures, such as modifications of mass distributions or water regimes, are often too expensive or difficult, if not impossible, when dealing with complex instabilities of large volumes (Crosta and Agliardi, 2003; Blikra, 2012). Efficient landslide EWSs require four major elements that have to be well integrated: (1) risk assessment, (2) phenomenon monitoring and forecasting, (3) warning communication and alert dissemination, and (4) local response aptitudes (UN-ISDR, 2009)

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Conclusion