Research on recently occurred reservoir-induced Kamenziwan rockslide in Three Gorges Reservoir, China

A landslide occurred in Kamenziwan, Zigui, the Three Gorges Reservoir area, located about 43 km from the dam on December 10, 2019. Due to a successful early warning system, no casualties were reported following the Kamenziwan landslide. However, roads, citrus groves, water supply lines, and 280-V power lines were damaged, resulting in a direct economic loss of 5.8 million RMB. This landslide is a newborn, wedge-shaped (apparent dip) red-layer rockslide, controlled by double-slip surface and covers an area of about 2.1 × 104 m2 and a volume of about 42 × 104 m3. The sliding mechanism includes leading-edge traction in the early stage and middle-rear gravity displacement in the late stage. The landslide movement was rapid, with a maximum sliding velocity of about 0.15 m/s, a movement time of more than 15 min, and a movement distance of about 18 m. Based on our investigation, the Kamenziwan landslide is not triggered by the reservoir water level and rainfall; indeed, this landslide has no obvious triggering factors. The results from our study suggest the long-term water level fluctuation in the Three Gorges Reservoir area has eroded the key anti-slip section in the middle-lower part of the Kamenziwan landslide, greatly accelerating its evolution process. The landslide that occurs “naturally”, due to the degradation of rock mass in the water level fluctuation zone, may be an important path for the development of new landslides in the later stage of water impoundment. The Kamenziwan landslide is of great reference value for understanding the development of a new type of reservoir-induced landslide in the Three Gorges Reservoir area. Comprehensive studies on this landslide help to identify potential geohazards, similar to Kamenziwan landslide, in the early stage of their development.