Tsunami Squares modeling of the 2007 Dayantang landslide generated waves considering the effects in slide/water interactions

Landslide tsunami in reservoirs can inflict serious consequences and they have aroused social concern worldwide. Herein, we introduce a historical reservoir tsunami that occurred on June 2007 in Shuibuya Reservoir, China. After a progressive failure over 20 days, the Dayantang slope with a volume of 3 million cubic meters slid into the Shuibuya Reservoir and spawned a giant tsunami that ran up ~50 m on the opposite shoreline and caused disastrous consequences. To model the 2007 tsunami, we apply a meshless numerical approach called ‘Tsunami Squares’ (TS) that takes into account the landslide/water interactions. TS simulates both the landslide and its generated tsunami and introduces ‘Push Ahead’ (PA) and ‘Drag Along’ (DA) accelerations to mimic the physical mechanics in the process. The accuracy and efficiency of TS method are verified by a well-designed landslide tsunami experiment that compares the observed wave dynamics with the ones simulated by TS and achieves an excellent match between the two. Landslide simulations indicate a maximum impact velocity of ~20 m/s and that the computed post-slide mass stopped on the near river bed with a shape coinciding with the field observations. Wave simulations present a large region of wave impacts and a maximum wave runup height of 52.9 m at the opposite bank facing the landslide scarp that is comparable to the observation (~50 m). Sensitivity analysis that compares the simulations with, and without, PA and DA accelerations is carried out both for the experimental wave and the 2007 one. This comparison indicates that TS simulations that do not include PA and DA can seriously underestimate landslide tsunami size.