In recent years Time Domain Reflectometry (TDR) has been introduced as a new system for subsurface deformation monitoring in boreholes. AsTDR can easily be operated continuously using dataloggers it is an economic alternative to expensive inclinometer chains. To date TDR can identify and localize discrete deformation zones with high accuracy. AsTDR measurements are influenced by a great variety of parameters, as for instance the used coaxial cable and grout type, they often are ambiguous, thereby hindering the quantification of the deformation. By the definition of calibrated installation standards and the usage of signal analysis software, it is possible to overcome this and reliably quantify deformation using TDR. Since TDR data can be acquired continuously as well as remotely, it is possible to integrate a TDR measuring system into a geo-sensor network.
In context of the global climate change an increase of extreme precipitation events is expected for Europe and the Alps (Alcamo et al. 2007). As heavy rainfall is an important trigger for landslides, the frequency of hazardous landslide events is also expected to rise. Luckily in most alpine regions the awareness of landslide hazards has risen in the last years, driven by national and regional hazard mapping programs. Although many potentially hazardous landslides have been identified, due to economic reasons only few are continuously monitored. In many cases only sporadic geodetic surveys are performed, which is not sufficient when infrastructure or even human life is at risk. In order to overcome this, efficient and economic measurement systems for landslide monitoring are needed. In order to evaluate a deep seated landslide, observations from the surface are not sufficient. Detailed information about the depth of the slope movements and their changes through time are needed. The direct measurement of subsurface deformations is only possible in boreholes.
