Vol20 No.12:3614-3630

【Title】Deformation characteristics and mechanism of an impoundment-induced toppling landslide in Baihetan Reservoir based on multi-source remote sensing

【Author】ZHOU Zhen-kai^1,2,3,4; YAO Xin^1,2,3*; LI Ren-jiang⁵; JIANG Shu⁵; ZHAO Xiao-ming⁵; REN Kai-yu^1,2,3; ZHU Yi-fei^1,2,3,4

【Addresses】1 Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China; 2 Key Laboratory of Active Tectonics and Geological Safety, Ministry of Natural Resources, Beijing 100081, China; 3 Research Center of Neotectonism and Crustal Stability, China Geological Survey, Beijing 100081, China; 4 School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China; 5 Office of Relocation & Resettlement, China Three Gorges Corportation, Chengdu 610095, China

【Corresponding author】YAO Xin

【Citation】Zhou ZK, Yao X, Li RJ, et al. (2023) Deformation characteristics and mechanism of an impoundment-induced toppling landslide in Baihetan Reservoir based on multi-source remote sensing. Journal of Mountain Science 20(12). https://doi.org/10.1007/s11629-023-7903-2

【DOI】https://doi.org/10.1007/s11629-023-7903-2

【Abstract】Impoundment and water level fluctuations in reservoirs can induce landslides, especially during initial filling and drawdown. Since the initial impoundment in April 2021, multiple landslides have occurred within the Baihetan (BHT) reservoir, which is located at the boundary of Sichuan and Yunnan province in southeast China. However, due to the complex terrain conditions of reservoir banks, traditional landslide research methods, such as surveys, deformation monitoring, and geotechnical experiments, cannot be effectively conducted in a timely manner. In recent years, the development of remote sensing technology has addressed the shortcomings of traditional landslide research methods that may not be promptly carried out. In particular, interferometric synthetic aperture radar (InSAR) technology, capable of measuring subtle deformations, and portable small unmanned aerial vehicles (UAVs) have played a significant role. This study integrates multiple remote sensing data sources, including InSAR results, optical remote sensing images, digital elevation model (DEM), and UAV imagery, to investigate and elucidate the deformation characteristics and mechanisms of the Xiaomidi (XMD) landslide developed on the left bank of Jinsha River, about 100 km from the BHT hydropower dam site. The spatial deformation distribution of the landslide before and after impoundment and the deformation time series during filling were examined. Monitoring water level variation and analysing the deformation process of the landslide were achieved by employing continuous synthetic aperture radar (SAR) intensity images and DEM. UAV photography was utilized to assist in the verification of ground deformation. The findings suggest that the weak strength of the reversed bedding strata structure and the steep slope eroded by the Jinsha River are inherent factors that contribute to the development of the landslide. The rise in the water level leads to softening of the rock mass at the slope toe, thereby directly facilitating the acceleration of landslide deformation. The toppling deformation of the lower rock mass initiates the formation of surface cracks and localized uneven subsidence in the overlying colluvial deposits.

【Keywords】Landslide; InSAR; Toppling deformation; Baihetan Reservoir; Jinsha River