The effect of temporal wave averaging on the performance of an empirical shoreline evolution model

• Published in: Coastal engineering (Amsterdam) 2011-08, Vol.58 (8), p.802-805
• Main Authors: Davidson, M.A., Turner, I.L., Guza, R.T.
• Format: Article
• Language: English
• Subjects: Argus; Coefficients; Earth sciences; Earth, ocean, space; Empirical analysis; Exact sciences and technology; Geomorphology, landform evolution; Intervals; Marine and continental quaternary; Mathematical models; Prediction; Shoreline; Shorelines; Skills; Statistics; Surficial geology; Temporal logic; Video; Wave averaging
• ISSN: 0378-3839; 1872-7379
• DOI: 10.1016/j.coastaleng.2011.03.007

The effect of using time-averaged wave statistics in a simple empirical model for shoreline change is investigated. The model was first calibrated with a six-year time series of hourly wave conditions and weekly shoreline position at the Gold Coast, Australia. The model was then recalibrated with the hourly waves averaged over intervals up to 1 year. With wave averaging up to 2 days, model performance was approximately constant (squared correlation r 2 ~ 0.61–0.62), with only small changes in the values of empirical model parameters (e.g. the beach response coefficient c varied by less than 4%). With between 2 and 40 day averaging, individual storms are not resolved; model skill decreased only modestly (r 2 ~ 0.55), but c varied erratically by up to 40% of the original value. That is, optimal model coefficients depend on wave averaging, an undesirable result. With increased averaging (> 40 days) seasonal variability in the wave field is not resolved well and model skill declined markedly. Thus, temporal averaging of wave conditions increases numerical efficiency, but over-averaging degrades model performance and distorts best-fit values of model free parameters.