Three-dimensional landslide surface deformation retrieved by SISTEM method: a case study at Qingjiang river in Changyang County, China

Current methods for obtaining surface deformation of landslides are mostly time-consuming, costly, and can only capture the motions of sparse points. By combining InSAR data and high-precision three-dimensional GNSS data, the three-dimensional deformation field can be obtained. This study introduces the Simultaneous and Integrated Strain Tensor Estimation from geodetic and satellite deformation Measurements (SISTEM) method into the retrieval process of landslide. This method can be very useful but has rarely been applied to the characterization of landslide kinematics. The results can be used in order to recognize the eventual presence of zones having different kinematics, so we apply SISTEM for the first time to detect 3D deformation on a reservoir slope in Yichang Province, China. The output of InSAR after calculating the atmospheric contribution by external data from the ERA-5 global meteorological model was integrated with local GNSS data into the SISTEM framework to decompose the measurements into a 3-dimensional velocity field. Finally, the kinematic characteristics of the studied landslide surfaces were determined. The middle region exhibits the highest deformation rate along the slope with the maximum horizontal deformation rate of 10 mm/a, primarily showing uplift with vertical deformation rates of 3 mm/a. In contrast, the rear of the slope experiences mainly downward movement, with a maximum vertical deformation rate of -15 mm/a. The proposed method provides a convenient and rapid way to obtain spatially continuous surface movement characteristics of landslides, offering a more direct and reliable scientific reference for landslide disaster warning and instability risk assessment.