Spatial analysis and hazard assessment of large-scale ancient landslides around the reservoir area of Wudongde hydropower station, China

The complex geological environment and strong tectonic movement have led to the development of a large number of ancient landslides along the Jinsha River. These landslides exhibit characteristics of large-scale, complex formation mechanisms, multiple sliding periods, and high potential hazards. In this study, we aim to construct an ancient landslide inventory and conduct potential landslide hazard assessment of the Wudongde hydropower station section and its surrounding areas, which is located in the downstream area of Jinsha River. We used the visual interpretation method to recognize large ancient landslides based on high-resolution remote sensing images on the Google Earth platform and analyzed the correlations between the landslide abundance and different influencing factors. Our results show that there were 3126 ancient landslides in the study area, covering a total area of 502.64 km(2). The statistical analysis indicated that the landslide occurrence is closely related to the slope gradient and topographic relief, and the landslide abundance index increases with the increase in above two influencing factors. In addition, the ancient landslides gradually decreases with the increase in the elevation, indicating that ancient landslides are more likely to occur in lower elevation areas, i.e., lower portion of the hillslopes. In addition, combining with machine learning method (logistic regression), the potential landslide hazard assessment of the study area was calculated by the hypothetical earthquake scenario of 10% exceedance probability in 50 years. The predicted result shows that the extremely high-hazard area of landslides appeared around the hydropower station, and the high-hazard area was mainly distributed within a 5-km range along both banks of the Jinsha River. This study provides basic data and important reference for the distribution characteristics and potential hazard assessment of ancient landslides in the reservoir area of Wudongde hydropower station.