The ENGAGE working group (Geomorphological Systems and Risk Research at the Institute for Geography and Regional Research) has been running a long-term monitoring project to investigate landslides in Lower Austria. Landslides (translational and rotational failures, debris flows, rock avalanches, rock falls, etc.) number among the most abundant natural hazards in Lower Austria. Resulting from sporadic phases of activity it is essential to generate specific long-term measurement series, enabling the analysis of changes in surface movements as well as underground in connection with triggering factors. Therefore, in 2014 the project “NoeSLIDE – Monitoring diverse types of landslides in Lower Austria” was initiated. The research sites are compiled under the parent site "LTER NoeSLIDE" which has three subsites, of which one is the Hofermühle Landslide Observatory.
The Hofermühle site is located in the district of Waidhofen a.d. Ybbs, Lower Austria. The site is located in the Flysch Zone, a geologically predestined zone known to be extremely prone to landslide processes in Austria. Within the 0.15 km² hydrological catchment of the Hofermühle torrent, landslide processes can be defined as complex, being constituted by shallow earth sliding in the middle and gently inclined part of the catchment nearby the torrent, accumulation of material and resulting earth flowing down the steepening torrent path. It can be defined as complex earth slide - earth flow, which has shown different phases of activity in the last 10 years on different parts of the landslide mass. Major activation occurred in 2011 (subsidence via sliding by 2 m in 2 weeks), re-activation in 2013 (formation of earth flow with 20m/h) and processes have slowed down significantly since then to only a few cm to dm per year on the parts affected by sliding – as far as known.
To investigate both surface and sub-surface dynamics and potential interrelations, a varity of permant and individual measurement techniques are applied at the study site. Direct investigations include dynamic probing, percussion drilling and core sampling. Hydro-meteorological parameters are acquired via TDRs (time domain reflectrometry) probes, piezometers for groundwater estimation and a meteorological station (precipitation, temperature, snow height, wind, solar radiation). Sub-surface displacements are measured with both manual and automatic inclinometers. Surface dynamics are investigated via multi-temporal TLS (terrestrial laser scanning) and UAV-based SfM (unmanned aerial vehicle; structure from motion) data. Data from permanent installations is given in 5 min resolution (TDR, piezometer, meteorological station, inclinometer).
