Enhanced Kinematic Inversion of 3‐D Displacements, Geometry, and Hydraulic Properties of a North‐South Slow‐Moving Landslide in Three Gorges Reservoir.

Complete three‐dimensional (3‐D) movements of slow‐moving landslides are critical to enhancing the understanding of the landslide mechanism. Multi‐source synthetic aperture radar (SAR) observations provide an opportunity to derive 3‐D movements. However, deriving the complete 3‐D movements faces potential challenges of incoherent phases and an ill‐posed inverse problem, which may result in incomplete and inaccurate results, especially for slopes facing north/south. Here, we propose a topography‐constrained strain model, which exploits the spatial relationship of 3‐D deformations between neighboring points as well as the assumption of the surface parallel flow of landslide, to derive complete 3‐D movements. Both synthetic and real datasets over the north‐south Xinpu landslide complex are utilized, to assess if the implemented method can overcome the ill‐posed condition and retrieve the complete 3‐D movement field. With the multi‐source SAR datasets, the performance of various datasets and the potential of NISAR in deriving time series and 3‐D movements are assessed. Based on the derived complete 3‐D movements and long‐term InSAR measurements, the landslide metrics, including elementary parameters of landslide geometry, spatial‐temporal patterns of movement, thickness, and hydraulic diffusivity, are derived to reveal that (a) the thickest landslide mass concentrates in the toe of the landslide, and (b) the effects of precipitation are more significant than those of the water level fluctuation in the Xinpu landslide complex, Three Gorges Reservoir areas. Plain Language Summary: Landslides are a dangerous geological phenomenon that can be difficult to monitor in site. Researchers have used radar remote sensing technology (i.e., SAR) to study landslides, which can provide valuable information about how they move and change over time. However, there are challenges in accurately estimating the complete three‐dimensional (3‐D) deformations, especially when landslides are facing north or south. In this study, we developed a new method to derive complete and accurate\3‐D deformations for landslides by using multi‐source SAR observations. The method was firstly tested on the simulated data, and then successfully applied in the Xinpu landslide complex in Three Gorges Reservoir area, China. Based on the derived 3‐D deformations, the characteristics of the landslide, including movement patterns, basal geometry, and hydrological influence, were investigated. Our findings suggest that rainfall has greater impacts on landslide than changes in water levels, and a significant transport tunnel is located from the middle to the submerged region. These novel insights can help researchers better understand the causes and effects of landslides and potentially improve efforts to mitigate their impacts. Key Points: Constraints from topography and strain model enable the retrieval of complete 3‐D movements for landslides using multi‐source SAR datasetsThe potential of novel features of forthcoming NISAR datasets in deriving accurate 3‐D movements for landslides is demonstrated3‐D deformation field yields key insights into the Xinpu landslide's movement patterns, basal geometry, and hydrological influence [ABSTRACT FROM AUTHOR]