Three-dimensional experimental investigation on hazard reduction of landslide-generated impulse waves in the Baihetan Reservoir, China

Dealing with the risk of landslide-induced impulse waves is a significant challenge in the management of large reservoirs after impoundment. After the impoundment of the Baihetan Reservoir in Jinsha River, the WangJiaShan (WJS) landslide has been one of most active reservoir-induced landslides, and the Xiangbiling Community located on the opposite bank is at great risk of impulse waves. Based on the WJS landslide, five experiments in a physical model with dimensions of 30 m × 27 m × 1.5 m were conducted at a scale of 1:150. Measurements were performed with wave gauges and a particle image velocimetry system. The maximum potential sliding velocity of the natural WJS landslide was approximately 7.11 m/s, and the maximum amplitude of the generated impulse wave was 7.68 m at a water level of 825 m above sea level. The complex estuary topography of the Xiaojiang and Jinsha Rivers caused the generated waves to impact the Xiangbiling Community multiple times, with a maximum run-up of 11.75 m. This risk of impulse waves is significantly reduced when the sliding volume is decreased. As the landslide volume was reduced from 611 × 10 4 to 448 × 10 4 m 3 by removing the upper part, the potential landslide velocity and the submerged sliding mass decreased, and the kinetic energy of the submerged sliding mass decreased from 2.69 × 10 11 to 10.03 × 10 9 J, i.e., by approximately 96.3%. The maximum amplitude of the potential impulse wave decreased from 7.68 to 2.81 m, and the area with an amplitude larger than 1 m decreased by 75.4%. When removing 163 × 10 4 m 3 , the impulse wave would no longer impact the community, which is recommended as the main reduction scheme for the WJS landslide. If the factor of safety of the WJS landslide after removal is required to be greater than 1, the removed volume needs to be approximately larger than 303 × 10 4 m 3 , resulting in higher cost. This study provides a technical basis for the prevention and control of WJS landslide-induced impulse waves and a useful reference for their hazard reduction around the world.