Integrated Monitoring of a Slowly Moving Landslide Based on Total Station Measurements, Multi-Temporal Terrestrial Laser Scanning and Space-Borne Interferometric Synthetic Aperture Radar

Abstract

Continuous landslide monitoring is a crucial task for the management of natural hazards for identifying suitable mitigation measures, including nature-based solutions. In the present study, three monitoring techniques including (i) an automated tracking total station (ATTS), (ii) multi-temporal terrestrial laser scanning (TLS) and (iii) space-borne interferometric synthetic aperture radar (InSAR) are applied to monitor the spatio-temporal displacement patterns of the Vögelsberg landslide (Tyrol, Austria) between 2016/05 and 2020/06. The landslide shows spatially and temporally varying displacement rates with up to 12 cm/a and a mean annual displacement of 4 cm/a. The results show that only the ATTS provides sufficient temporal resolution and spatial accuracy for assessing the temporal behaviour of the landslide's movement. However, ATTS measurements are only available at the installed 53 retro-reflecting prisms. Multi-temporal TLS can provide additional insight into the spatial displacement pattern at various man-made and natural objects such as walls, fences, poles and tree stems. But the respective accuracy and data acquisition intervals do not allow to draw conclusions about the temporal dynamics of the landslide's movement. Results of the InSAR technique based on Sentinel-1 imagery show good agreement with ATTS measurements, but cannot provide real-time information on the landslide's acceleration and deceleration phases. However, in combination, the measurement techniques provide vital information in both the spatial and temporal domain.