f Monitoring landslides in the Three Gorges region, China, using multiple SAR techniques

Landslides have long been the most frequent and widespread geohazard in the Three Gorges region. Over the last decade, construction ofthe Three Gorges dam project has created a 600 km long reservoir with a bi-annual fluctuating water-level which has also been shown to reactivate ancient landslides. InSAR techniques have demonstrated the ability to monitor ground deformation with centimetre precision over large areas and offer the most comprehensive method for monitoring landslides in the Three Gorges region. Within the study area, major limitations include atmospheric water vapour, steep slopes and in particular, temporal decorrelation between SAR image acquisitions caused by dense vegetation. When interierograms are incoherent, it restricts the ability to extract a reliable time-series of measurements. To combat this problem, pixel-offset techniques using SAR amplitude images have been employed to enhance the coverage of measurements within the landslide areas and a small-baseline time-series approach (similar to the SBAS-lnSAR time-series approach) has been used to monitor the evolution of landslide movements.