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| Prediction of the maximum near-field wave amplitude of impulse waves generated by three-dimensional landslides based on momentum balance |
| HAN Linfeng1，2，WANG Pingyi1 |
(1. National Engineering Technology Research Center for Inland Waterway Regulation，Chongqing Jiaotong University，Chongqing 400074，China；2. National Center for Computational Hydroscience and Engineering，University of Mississippi，
Oxford 38677，USA)
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Abstract When a slope slides into water，it creates the impulse waves whose effects may be catastrophic. Assessing the risk posed by such events requires the estimation of the characteristics of waves，especially in the near-field zone. The momentum rate from a landslide upon impacting the water body is the driving force for the generation of impulse waves. The theoretical relationships for the maximum near-field wave amplitude generated by three-dimensional deformable landslides are derived considering the momentum transfer under the hydrostatic and hydrodynamic assumptions. The three-dimensional experiments on tsunami generation by landslides were carried out in a wave flume. The comparisons between the measured values and the predicted wave amplitudes using the novel momentum-based equations indicate that the maximum near-field amplitude generated by three-dimensional landslides is far less than the breaking limit of solitary wave，and thus the wave will not break in the near-field. The results from the theoretical equations are in agreement with the laboratory data if the landslide is completely submerged after deposition. However，for the slope sliding into the shallow water，if the water depth is below the critical depth，the measured near-field amplitudes decrease sharply with the decreasing of water depth，which is opposite to the theoretical relationships. The similar results were also obtained in the three-dimensional experiments by Mohammed(2010) and in Gongjiafang case. The near field characteristics of landslide generated impulse waves for the cases of deep water and shallow water should therefore be studied separately. After discussing the limitations of the theoretical models，a new momentum-based method for predicting the maximum near-field wave amplitude is thus proposed.
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2018, Vol. 37 
