Direct comparison of insar, uav & rtk deformation methods at north slide, thompson river valley, british columbia, canada

This study focusses on the North Slide, an active landslide that poses a hazard to the national railway traversing the Thompson River valley. The slide acts as an ideal field laboratory for testing and evaluating novel landslide monitoring and evaluation techniques. In this study, we present results of a direct comparison of several commonly used land deformation measurement techniques that have been used to monitor the North Slide for several years. Ground-based Real Time Kinematic (RTK) Global Positioning System (GPS), Unmanned Aerial Vehicle (UAV), and satellite-based Interferometric Synthetic Aperture Radar (InSAR) measurements were collected over the course of two years (2020-2022). Deformation measurements calculated from these repeat surveys are directly compared both spatially and temporally to evaluate their relative accuracy and precision. We find that the InSAR and UAV based deformation measurements agree in terms of movement zone extents and general magnitude. The InSAR measurements more closely reflect the GPS measurements and have a smaller distribution around stationary points than the UAV based deformation. The errors between the UAV and InSAR measurements also appear to scale with the magnitude of deformation. The 1 sigma and 2 sigma differences between the UAV and InSAR deformation measurements were 0.025 m/year and 0.051 m/year, respectively.