Numerical estimation of river blockage and the whole lifecycle of landslide-generated impulse waves in mountain reservoirs using a hybrid DEM-SPH and SWEs method

Landslides occurring in mountain reservoirs could induce severe geological hazards, posing substantial risks on both the infrastructure and life. Considering the hazards always encompass different spatial and temporal scales, this paper proposes a novel hybrid Discrete Element Method (DEM) - Smoothed Particle Hydrodynamics (SPH) and Shallow Water Equations (SWEs) method to study the landslide motion and the whole lifecycle of LGIWs in a mountain reservoir. In the proposed method, the connecting between the DEM-SPH model and SWEs model is realized by transferring the hydrodynamic condition from the DEM-SPH model to SWEs model after the landslide halts, and the topography of the river channel is reconstructed based on the deposit morphology. After the validation, this method is applied to predict the hazard chains induced by ZJ landslide. The processes of landslide sliding, accumulation, impulse wave generation, propagation, running up on the dam, and dissipation are studied. The deposit morphology of the landslide and the distribution of the maximum water level are obtained. In addition, some special phenomena, such as the drainage of water from the deposit, dam-break-liked impulse waves, multiple reflections of impulse waves between the deposit and dam, and the rise of water level, are discovered under the influence of both river topography and landslide deposit. This study presents the first application of the 3D coupled DEM-SPH model in the nested near-field and far-field method, provides a useful method to comprehensively study the whole landslide-induced hazard chains in mountain reservoirs, and offers valuable references for disaster prevention and reduction.