Refinement of integrated formula of wave overtopping and runup modeling

This study attempts to refine a model named the Integrated Formula of Wave Overtopping and Runup Modeling (IFORM) to improve the prediction performance of mean wave overtopping discharge for a broader range of installation conditions. The empirical formula describing the relation between overtopping discharge and maximum runup has been re-examined. A set of piecewise formulas is implemented in the IFORM by optimal reconstruction of coefficients depending on the magnitude of deficit in freeboard. The refined IFORM improves the tendency to underestimate the discharge in the range of relatively high freeboard conditions, while it retains the high performance of the original IFORM in the range where the crest freeboard is relatively low. The refined model's capability for overtopping prediction is validated by comparison with various existing experimental datasets for inclined/vertical seawalls installed at relatively shallow water depth or on land. The prediction accuracy is also examined by comparison with well-known overtopping formulas. Qualitative and quantitative comparisons validate that the current model is able to reproduce the experimental observations over a broad range of overtopping conditions and that the performance of the model proposed in the present study is as good as existing representative models. •Prediction performance of a unified wave runup and overtopping model is improved.•Regression between runup and overtopping is optimized based on deficit in freeboard.•Refined model can reproduce hydraulic experiments over a broad range of conditions.•Quantitative accuracy of refined model is as good as existing overtopping formulas.•This model can be applied to inclined/vertical seawalls at shallow water or on land.