Large-scale damming landslides frequently occur in high-relief mountainous regions in the Tibetan Plateau where is characterized by active tectonics and intense fluvial incision, which commonly result in flood, landslide reactivation, and some other secondary disasters. Such favorable conditions for geohazards will severely affect the construction safety of vital projects of China, i.e., Sichuan-Tibet and Yunnan-Tibet Railways. However, general developing laws of landslide damming and simulation of whole process of disaster chain have not been properly accounted for in the Tibetan Plateau. It is essential to establish a database of landslide dammings in the Three Rivers Region in the Tibetan Plateau for better obtaining the general laws. This study conducted detailed geological survey and mechanism analysis on landslides that have blocked valley river in the year of 2019, and periodically revealed the following conclusions: (1) suture and active fault not only alter the rock mass of hillslope and affect rock integrity and weathering extent, but also usually generate seismic events to trigger large landslides which slide rapidly and likely block rivers; (2) landslide dammings are prone to occur on the anaclinal hillslopes when river continuously erodes the concave bank, which would develop toppling deformations to a large-scale catastrophic landslide to block rivers; (3) anticline nucleus formed in the middle of a river valley commonly induces landslide damming by developing anaclinal hillslopes that would easily evolve into large landslide from toppling owing to the fragmented rock mass nearby the anticline; (4) chemical weathering of carbonaceous rock in the slope could facilitate the failure of large landslides. Large-scale rockslides will cause severe river blockage, flood and other disaster chain in mountainous region as long as the favorable geo-environment develops. An understanding of general developing laws of landslide damming in the Three Rivers Region could provide a conceptual model for our next work about the landslide database and is helpful to confront more challenges for disaster prevention and mitigation.
