Effect of wave frequency and directional spread on shoreline runup

Abstract

[1] Wave breaking across the surf zone elevates the mean water level at the shoreline (setup), and drives fluctuations about the mean (runup). Runup often is divided into seaswell (0.04-0.3 Hz) and lower frequency infragravity (0.00-0.04 Hz) components. With energetic incident waves, runup is dominated by infragravity frequencies, and total water levels (combined setup and runup) can exceed 3 m, significantly contributing to coastal flooding and erosion. Setup and runup observations on sandy beaches are scattered about empirical parameterizations based on near-shoreline beach slope and deep water wave height and wavelength. Accurate parameterizations are needed to determine flooding and erosion risk to coastal ecosystems and communities. Here, numerical simulations with the Boussinesq wave model funwaveC are shown to statistically reproduce typical empirical setup and runup parameterizations. Furthermore, the model infragravity runup R s (ig) strongly depends on the incident wave directional and frequency spread (about the mean direction and peak frequency). Realistic directional spread variations change R s (ig) equivalent to a factor of two variation in incident wave height. The modeled R s (ig) is shown to vary systematically with a new, non-dimensional spreading parameter that involves peak frequency, frequency spread, and directional spread. This suggests a new parameterization for R s (ig) potentially useful to predict coastal flooding and erosion. Citation: Guza, R. T., and F. Feddersen (2012), Effect of wave frequency and directional spread on shoreline runup, Geophys.

The use of genetic programming to develop a predictor of swash excursion on sandy beaches

“…For instance, we do not include the influence of the wavedirectional spread (Guza and Feddersen, 2012), the crossshore wind component and the tidal range (Vousdoukas et al, 2012). However, in order to include these and other aspects (e.g.…”

The use of genetic programming to develop a predictor of swash excursion on sandy beaches

“…For instance, we do not include the influence of the wave directional spread (Guza and Feddersen, 2012), the cross-shore wind component and the tidal range (Vousdoukas et al, 2012). However, in order to include these and other aspects (e.g., role of underwater vegetation) it is necessary to perform more field experiments that record swash, runup and other relevant variables.…”

Two-Dimensional Wave Overtopping Calculation Over a Dike in Shallow Foreshore by Swash

“…Van Gent, 1999) are limited in applications compared to ones for deep water conditions. Also, there is an uncertainty for the two-dimensional effect for the wave overtopping in the shallow foreshore condition: a recent numerical study (Guza and Feddersen, 2012) shows that the directional spreading, in other words short-crestedness of the waves, influences the run-up height. It indicates that the wave overtopping calculation in the shallow foreshore condition must account for the two-dimensional effects.…”