Insights into landslide development and susceptibility in extremely complex alpine geoenvironments along the western Sichuan–Tibet Engineering Corridor, China

Abstract

The Sichuan–Tibet Engineering Corridor (STEC), which provides the key function of transportation between the plain and plateau regions, is subjected to widely distributed landslides in the southeastern margins of the Tibetan Plateau. This study investigated the landslides in terms of geomorphological and geological analyses and susceptibility assessment along the western STEC between Changdu and Nyingchi Cities, which is characterized by extremely complex geoenvironments across three major river catchments. The results suggested the spatial feature that the landslides preferentially occurred in river valley regions with high elevation and distinctive local relief. Soft rock types of shale, siltstone, schist and gneiss controlled most landslide areas, while faults and rivers strongly dominated landslide formation. Landslide susceptibility results performed by the support vector machine (SVM), k-nearest neighbor (KNN), and multilayer perception (MLP) models were highly dependent on various sample sets, revealing different hazard-formation backgrounds among the Lancang, Nu, and Yarlung Tsangpo (YLTP) river catchments. A comparative analysis demonstrated the most robust model, the SVM, indicating that lithology, elevation, local relief, slope, and distance to faults were the most significant factors causing landslides. In summary, the investigations signified that the development of landslides along the STEC was macroscopically controlled by regional and vertical zonation of the tectonic geomorphology driven by regional uplift, and was locally dominated by lithology and suture zones. Eventually, further surface erosion and earthquakes dynamically offered inducements for landslide initiation. This study strengthens the understanding of landslide development and susceptibility in response to landscape evolution in southeastern Tibet, and provides a conceptual model for disaster prevention and mitigation in similar high-relief plateau margin regions.