NONLINEAR TIME-AVERAGED MODEL IN SURF AND SWASH ZONES

Bradley D. Johnson, Nobuhisa Kobayashi

Abstract


A time-averaged model is developed to predict the cross-shore variations of the mean and standard deviation of the free surface elevation from outside the surf zone to the lower swash zone on beaches. This new model includes nonlinear correction terms in the cross-shore radiation stress and energy flux that become important in very shallow water. Empirical formulas are proposed for the skewness and kurtosis as well as the ratio of the root-mean-square wave height to the mean water depth which increases rapidly near the still water shoreline. The developed model is shown to be in agreement with three irregular wave tests on a 1:16 smooth impermeable slope and two tests of quasi-equilibrium terraced and barred beaches. The model can predict the observed large increase of wave setup near the still water shoreline. The developed model and empirical formulas will need to be verified using additional experiments.

Keywords


swash zone; surf zone; nonlinear waves; wave model

Full Text: PDF

Creative Commons License
This work is licensed under a Creative Commons Attribution 3.0 License.