The usage of modern remote sensing techniques in monitoring and mapping of landslide and snow related natural hazards

The use of remote sensing techniques in natural hazards has been increasing due to technological and scientific developments. The present study examined the use of modern remote sensing techniques in landslide and snow/avalanche case applications within five study areas selected from three countries (i.e., Turkey, Austria and Switzerland). These selected modern remote sensing techniques included unmanned aerial vehicle (UAV) systems, laser scanning systems (aerial and terrestrial), Synthetic Aperture Radar (SAR) interferometry (InSAR), and optical aerial photogrammetry. The landslide studies were carried out within two study areas in Turkey (Himmetoğlu and Devrek) and two in Austria (Gallenzerkogel and Gschliefgraben), while the snow/avalanche study was conducted in one study area in Switzerland (Dischma valley). Both UAV and aerial laser scanning data were used for landslide monitoring in the study areas located in Austria and the InSAR time series together with UAV and optical aerial photogrammetry were used for landslide monitoring in the study areas in Turkey. However, only UAV and terrestrial laser scanning (TLS) were used for monitoring snow depth mapping and snow cover ablation in the study area in Switzerland. For the monitoring of the Gschliefgraben landslide, only techniques for comparison of point clouds and the digital image correlation method were used via the available aerial laser scanning data. However, both UAV and laser scanning data were used to monitor the Gallenzerkogel landslide using both the Digital Elevation Model (DEM) of difference and the M3C2 algorithm, an advanced point cloud comparison method. A case study was carried out for monitoring snow cover ablation with UAV and TLS data obtained as a five-time series over the period of a month in Dischma valley (Davos, Switzerland). This case study is one of the first in which snow cover ablation was monitored using both UAV and TLS. For a long-term period (1992-2015), the surface deformation due to the Karşıyaka Road landslide (Devrek, Zonguldak) was monitored and mapped via persistent scatterers interferometry (PSI) analysis carried out using C-band SAR images from ERS-1/2, Envisat ASAR, and Sentinel-1 satellites. In addition to data from SAR satellites, the aerial photographs and UAV data were also used. Both PSI and small baseline subset (SBAS) analysis were carried out together with UAV data in order to obtain C-band SAR images of the surface deformation caused by the Himmetoğlu Village landslide (Göynük, Bolu) from the Sentinel-1 satellite. The usage possibilities of advanced remote sensing techniques in natural hazards were evaluated based on the findings of these case studies.