On the applicability of satellite SAR interferometry to landslide hazards detection in hilly areas: a case study of Shuicheng, Guizhou in Southwest China

SAR Interferometry (InSAR) has been proven to be effective for measuring landslides deformation. However, the InSAR application of landslide mapping is limited by the blind observation areas caused by SAR geometric distortion or vegetation decorrelation. We proposed an approach of landslide detection and mapping with a priori assessment of InSAR applicability, which can not only guide the selection of SAR data, but also prejudge the observable areas. Meanwhile, it can assist to analyze the reliability of landslide detection and help to reveal the reason of detection failure of occurred landslides. We employed this approach to evaluate the InSAR applicability over the whole Guizhou Province at first. Then, we took Shuicheng County as an example to conduct time-series InSAR landslide detection combined with a priori applicability. Six large active landslides were identified from the results of three SAR data stacks (ALOS-2 PALSAR-2 and ascending/descending Sentinel-1 from April 2017 to July 2019). The reliabilities of landslide detection results were analyzed and the possible reasons for the detection failure of Jicangzhen landslide were revealed. We inferred that the Jichangzhen landslide suddenly happened induced by short-term heavy rainfalls and presented no precursors, which cannot be captured by SAR satellites with intermittent observations.