An Enhanced Framework to Quantify the Shape of Impulse Waves Using Asymmetry

The shape of a wave generated by a landslide, snow avalanche, or fluid flow greatly influences its size and speed as it propagates away from the source region, which are critical parameters needed to estimate the impacts of these waves on coastal communities. In this study, laboratory data are produced from waves generated by the impact of water into a wave flume akin to the impact of a fluidized, highly mobile, and neutrally buoyant slide into a reservoir. Water surface observations are made using wave probes that remain at fixed positions, while the water depths and source volumes of slide material are varied. The wave shape is quantified by calculating the asymmetry about the vertical axis at each wave probe. The experimental results indicate that waves with positive or near‐zero asymmetry in the near field have a small influence on the maximum wave amplitude along the flume. However, waves with negative asymmetry in the near field change rapidly in shape and amplitude due to breaking until a stable state with symmetrical shape and wave breaking limit of 0.6 is reached. The length scale at which the breaking waves reach this state is quantified based on the initial asymmetry. An enhanced mathematical framework is developed using horizontal‐scale coefficients to modify the solitary wave equation such that it can be used to generate asymmetrical waves. This new method might be used in combination with predictions of the maximum wave amplitude to create time series needed to account for the shape of the tsunamis. Plain Language Summary The shape of a wave generated by an avalanche or landslide greatly influences its size and speed as it propagates away from the source region, which are critical parameters needed to estimate the impacts of these waves on coastal communities. In this study, laboratory data are produced from waves generated by the impact of water‐impact slides into a reservoir that propagate and evolve along a wave flume. Water surface observations are made using wave probes, and the water depths and source volumes of water are varied in the experiments. The wave shape is quantified by calculating the “asymmetry,” and the experimental results indicate that waves with positive or near‐zero asymmetry in the near field have small changes in the maximum wave amplitude along the flume. However, waves with negative asymmetry in the near field change rapidly in shape and amplitude due to breaking until a stable state with symmetrical shape is reache