Developmental characteristics and damming river risk of the Woda landslide in the upper reaches of the Jinshajiang River

The Woda landslide in the upper reaches of the Jinshajiang River, has been deformed since 1985, whose surface deformation characteristics are obvious now. There is a potential risk that the landslide will slide further and block the Jinshajiang River. Based on the remote sensing interpretation, field investigation, engineering geological drilling and comprehensive monitoring, the spatial structure and deformation characteristics of the landslide are analyzed, the potential reactivation instability pattern of the landslide is clarified, and the risk of landslide blocking river is discussed by empirical formula calculation. The results show that the Woda landslide is a huge landslide with a volume of about 28.81×10⁶ m³. It is speculated that the landslide had undergone massive sliding before the late Pleistocene. The whole landslide is currently creeping, and the local part of the landslide is in the accelerated deformation stage. The deformation range of reactivation zone is mainly concentrated in the middle and front parts, and the failure characteristics are progressive backward. The deformation on the right side of the reactivation zone is stronger than that on the left side. There are two sliding zones developing in the landslide, namely the shallow zone and deep sliding zone, whose average depth is about 15 m and 25.5 m, respectively. Accordingly, the landslide can be reactivated with two potential failure modes: the shallow slip and deep slip with progressive failure mode. When the sliding mass in the strong deformation area of the Woda landslide slides along the shallow sliding zone, the height of the landslide dam formed is about 87.2 m. If the whole sliding mass slides along the deep sliding zone, the height of the landslide dam formed is about 129.2 m. The Woda landslide has the risk of landslide-damming-outburst-flood chain disaster. It is suggested to further strengthen landslide monitoring and carry out drainage, reinforcement and other prevention works. This study can offer certain reference for preventing and controlling large geological disaster chain in the upper reaches of the Jinshajiang River.