Early identification and characteristics of potential landslides in the Bailong River Basin using InSAR technique

Abstract

The Bailong River Basin is located in the southeast of Gansu Province and situated at the intersection of the Qinghai-Tibet Plateau, the Loess Plateau, and the Sichuan Basin. Geohazards, such as landslides and debris flows, have high frequency and wide distribution due to the impact of rainfall, tectonic activity, and earthquakes. These phenomena pose a serious threat to the safety of life and property of the local people. Investigating a new method to detect potential landslide and study its characteristics is important to provide key supports for local disaster prevention and mitigation.In this study, an InSAR technique called Small Baseline Subset was selected to process 60 Sentinel-1A SAR images acquired from March 2018 to March 2019. Moreover, the study area was clipped into 8 blocks to improve the efficiency of data processing and minimize the errors caused by the complex terrain of the region.On the basis of the abovementioned method, the mean surface displacement rates ranging from -158 and 100 mm/year along the line-of-sight direction were detected during March 2018 and March 2019. A total of 114 potential landslides were investigated and identified in the Bailong River Basin based on optical image interpretation and field survey. Statistical analysis of their basic information shows that most of the potential landslides tend to develop in the S, SSW, and SSE-faced slope with a gradient of 20°-40°. The elevation difference of potential landslides is less than 150 m. The slope material is mostly composed of slope deposits and heavy weathered rocks, such as phyllite. The majority of potential landslides have an area less than 5×104 m2.Yahuokou landslide, which was investigated as a potential landslide with displacement rates > 38 mm/year, broke and ran into Min River from 19 July 2019. On the basis of the analysis of landslide pre-cursory deformation and geomorphology, the landslide was divided into three sections: source, propagation, and accumulation areas. The successful identification of potential landslide demonstrates the applicability and efficiency of InSAR technique in landslide investigation and identification. This research provides foundation and scientific support for landslide mapping and disaster prevention in Bailong River Basin. © 2021, Science Press. All right reserved.