Run-Up of Impulse Wave Trains on Steep to Vertical Slopes

Abstract

Impulse wave trains are generated by subaerial landslides, rockfalls, or avalanches impacting a water body. Especially in engineered reservoirs, the run-up of waves with small relative heights is critical due to the small freeboard between the still water level and the dam crest. To prevent overtopping, an accurate prediction of the maximum run-up height is important for dam safety and hazard mitigation. The run-up behavior of impulse wave trains on a plane and impermeable barrier with slope angles between 18.4° and 90° was investigated in a two-dimensional wave channel. New breaker-type criteria and a run-up prediction equation for the first five waves were developed. The main findings are that (1) wave crest celerity decreases monotonically from leading to following waves; (2) for nonbreaking and surging-breaking waves of the same wave crest amplitude, the leading wave does not induce the maximum run-up height; and (3) the proposed run-up equation predicts the run-up height of nonbreaking waves and surging breakers with a maximum underestimation of 25% and 40%, respectively. For plunging breakers, it may serve as an upper limit.