Dynamic evolution mechanism and subsequent reactivated ancient landslide analyses of the “6.17” Danba sequential disasters

• Published in: Bulletin of engineering geology and the environment Vol. 81; no. 4
• Main Authors: Jiang, Nan, Li, Hai-bo, Hu, Yu-xiang, Zhang, Jie-yuan, Dai, Wei, Li, Cong-jiang, Zhou, Jia-wen
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2022
• Subjects: Earth and Environmental Science; Earth Sciences; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Nature Conservation; Original Paper; Reactivation of an ancient landslide; Debris flow; Dammed lake; Sequential disasters; Remote sensing technology
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-022-02614-1

On June 17, 2020, a sequential disaster event, including debris flows, dammed lakes and the reactivation of ancient landslides, occurred in Danba County, Southwest China. The debris flow, which was triggered by short-term heavy rainfall, caused damage to houses and casualties, eventually leading to the blockage of the main channel of the Xiaojinchuan River as well as the formation of a debris flow–dammed lake. The outburst flood induced by the breakage of the debris flow dam caused devastating damage to dozens of villages, towns, and national highway G350 downstream. Moreover, an ancient landslide located on the left bank was reactivated during the outburst flood and experienced a large degree of deformation for several months. According to this sequential disaster event, we conducted on-site surveys and monitoring using three-dimensional terrestrial laser scanning (TLS) and unmanned aerial vehicles (UAVs). The development and dynamic evolution mechanism of the debris flow, dammed lake, and reactivated ancient landslide were illustrated based on the monitoring data. The results show that the erosion of outburst floods is the main cause of the deep and shallow sliding of the ancient landslide, and the presence of landslide deposits or unstable slopes near the debris flow dam sites is the key factor in the amplification and expansion of the disasters.