InSAR-based deformation analysis around the Qiaoqi reservoir, Baoxing, Southwest China

Abstract

After the initial impoundment of the Qiaoqi reservoir in 2007, numerous landslides were triggered, severely endangering the reservoir’s safety, people’s lives, and settlements. For efficient risk evaluation and mitigation approaches, it is essential to comprehend the extent and behaviour of these landslides. Synthetic aperture radar (SAR) data, especially with the Interferometric SAR (InSAR) techniques, provides continuous surface deformation with mm precision over substantial ranges. A stack of 31 Sentinel-1 images in ascending direction (2014/12-2017/07) is used for interferometric analysis using the Persistent Scatterers Interferometric (PS-InSAR) technique to identify deformation hot spots, determine displacement rates, and characterize deformation behaviour around the reservoir by taking Kadui-2 landslide as a case study. The mean deformation in the line of sight ranged from − 60 to + 60 mm/year around the reservoir, and from − 100 to + 100 mm/yr on the Kadui-2 landslide. Additionally, seven deformation hotspots were identified, with the NW and SW sections exhibiting larger deformation compared to the other regions along the reservoir. InSAR analysis reveals that the deformation rate of the Kadui-2 landslide is not associated with seasonal hydrological accelerations. The findings of this study help to understand the deformation behaviour and associated settlements around the Qiaoqi reservoir.