Background

Monitoring and Early Warning Systems for disaster prevention in landslide hazard management

Due to the progressive development and utilization of areas endangered by mass movements and changing climatic conditions, the risk for people and public infrastructure like roads, supply lines or facility utilities increases continuously. This increase and the fact that mass movements mostly occur together with other great natural disasters like hurricanes or earth quakes show, how important it is to develop tools to manage landslide hazard adequately. Especially in areas with unfavorable topographic conditions settlements and infrastructures are often located in direct neighborhood to landslide areas. This situation is being complicated by the fact that the dependency of our today’s society on a functioning infrastructure rises.

Active landslide in Southern France This development is not only a specific problem to Germany or mountainous regions. It is a global challenge, apparent from an increasing number of national and international programs Just in the USA landslides account for approximated annual losses of about 3.5 bn. USD and 25 to 50 fatalities a year (USGS, 2004). In this context monitoring and early warning systems becomes a reckoned pillar of disaster prevention in natural hazards especially where mitigation strategies are not realizable. Furthermore, internationally the call for multi-hazard early warning systems and improvement of monitoring of natural hazards is steadily growing.

Rockslide near Steinbergen, Lower Saxony Currently existing monitoring systems for early warning are monolithic in terms of isolated installations, which are very cost-intensive considering installation as well as operational and personal expenses. This results often in a selective monitoring with few measuring stations or observation points in an instable slope or an endangered rock face, instead of a favorable spatial monitoring. In many cases the limited information from single points is not adequate for a reliable interpretation or prediction, especially if the sampling rates are low. In this case the failure of some or even single measuring points leads to a partial or total breakdown of the monitoring system. Limited or missing data may also cause false alarms. Besides the costs of false alarms, the loss of confidence in the system by authorities and people in this case is much worse. Another critical point is the very complex information chain in case of warning, which requires a disciplined adherence to an emergency plan. A failure of single elements or even worse the missing of adequate emergency plans will significantly disturb the flow of information. This may cause in the worst case that a warning massage gets lost. For this reasons it is necessary to improve existing and to develop new monitoring and warning systems to meet the rising requirements to protect people and objects.