IRREGULAR WAVE OVERTOPPING OF REVETMENTS IN SURF ZONES

Twelve test runs were conducted to examine the overtopping processes of normally incident irregular waves over a revetment of a 1:2 rough impermeable slope fronted by a gentle, smooth slope and situated well inside the surf zone. The measured overtopping probability and average overtopping rate are affected noticeably by the spectral shape and wave grouping of the incident irregular waves measured immediately outside the surf zone. The empirical procedure for estimating these overtopping quantities is found to yield only order-of-magnitude estimates for this experiment. The measurements made for the 12 runs are used to calibrate and evaluate the existing one-dimensional, time-dependent numerical model, which is modified slightly to allow the spatial variation of the bottom friction factor. The calibrated numerical model is shown to be fairly capable of predicting the average overtopping rate and the depth of overtopping flow on the crest of the revetment. The measured and predicted time series and spectra of the flow depth including entrained air show the grouped nature of irregular wave overtopping events.