Satellite Radar Interferometry for Monitoring Slope Stability of the Huangtupo Landslide in the Three Gorges Reservoir Region Using Sentinel-1 and ALOS-2 Data

In this paper, the Huangtupo landslide in the Three Gorges Reservoir (TGR) was explored by the multi-source satellite SAR data from ALOS-2 and Sentinel-1A/B based on time-series InSAR analysis. One track of ALOS-2 and two tracks of Sentinel-1 SAR datasets acquired from August 2016 to October 2017 were used to investigate the surface deformations. The maximum line-of-sight (LOS) deformation rate measured over the slope surface was up to -50 mm/year from the ALOS-2 measurement, while it was as high as -40 and -30 mm/year for Sentinel-1 Track 11 and Track 84 measurements, respectively. Cross-validation between the multi-source InSAR results showed that the ALOS-2 and Sentinel-1A/B measurements are highly correlated. Time series displacement analysis of selected point clusters based on InSAR measurements from ALOS-2 and Sentinel-1 data stacks was also investigated along with the TGR water level and daily rainfall over this area. Seasonal fluctuations caused by changes in rainfall and TGR water level can be clearly observed from the time series evolutions of deformation. It is clearly found that the lower parts of the Huangtupo landslide are more likely to influenced by the TGR water level, while the upper parts mainly responses to the seasonal changes of rainfall.