Risk assessment of the Sedongpu high-altitude and ultra-long-runout landslide in the lower Yarlung Zangbo River, China

Abstract

The Tibetan Plateau is an area that is highly prone to high-altitude and ultra-long-runout landslides. The Sedongpu landslide is one very typical case. Aiming at high-altitude and ultra-long-runout landslides, and taking Sedongpu basin as an example, this study tries to establish analytical method through historical interpretation, potential source interpretation, numerical back-analysis, dynamic parameters acquisition, and numerical prediction analysis. The following results were obtained: (1) the high-altitude and ultra-long-runout landslide has obvious vertical and horizontal zoning characteristics, the vertical falling height difference and runout distance are linearly correlated to the complicated dynamic characteristics, which is one of the reasons why this type of disaster cannot be evaluated by conventional risk assessment methods. (2) Based on remote-sensing technology, the historical landslides events in 2018 were interpreted, and five potential high-altitude geo-risk areas were detected. There is still a very high geological disaster risk. (3) Through back- and prediction-analysis in numerical simulations, it was determined that the height of the Sedongpu landslide dam will reach 120 m and 165 m under general condition and extreme condition. The purpose of this study was to propose an alternative risk assessment method, which is of great significance for geo-risk prediction and mitigation.