Increase in hazard from successive landslide-dammed lakes along the Jinsha River, Southwest China

Multiple reactivation of a large landslide might dam river course at the same site in different periods, which would exert long-term and considerable influence on society and environment. In this paper, we consider such successive damming episodes as an integrated system and take the 2018 Baige event due to successive landslides as an example to explore the hazard characteristics of successive landslide-dammed lakes. Based on the river valley conditions at dam site before the first and second blockage, the height of dams formed by landslides with different volumes is estimated, and then the stability and peak discharge of these landslide dams are evaluated. The calculation results show that the hazard of the dammed lake triggered by subsequent slide event in the successive landslides could increase significantly. The cause of such hazard increasement of the subsequent landslide dam is also discussed. The experience obtained in this case study can facilitate better understanding the hazard characteristics of similar landslide-dammed lakes, as well as planning engineered controls in advance in order to decease the hazard of dammed lake formed by the potential subsequent landslide.