ICCE 2022

How to Cite

Kalligeris, N., & Gallien, T. (2023). STOCHASTIC BOUNDARY UNCERTAINTY IN MEAN WAVE OVERTOPPING RATE ESTIMATES. Coastal Engineering Proceedings, (37), structures.92.


Accurate backshore flood prediction requires quantifying overtopping volumes. Wave overtopping can be predicted through empirical formulas (e.g., EurOtop), neural networks or numerical modeling. The first two methods are easy to implement and provide rapid estimates for engineering design. However, empirical estimates reflect average overtopping rates, cannot resolve impulsive individual wave overtopping volumes or infragravity energy, and may differ from observational or numerical estimates by an order of magnitude (e.g., Gallien, 2016). Numerical models present an attractive alternative, however, predictions in phase-resolving models for spectral boundary conditions (BCs) vary due to the stochastic transformation to the time-domain, leading to significant errors in overtopping estimates when the prediction uncertainty is not accounted for. The purpose of this study it to derive an analytical formula for the coefficient of variation of the mean overtopping rate, applicable to all cases for which overtopping volumes are Weibulldistributed. Theory is used to provide guidance on estimating the uncertainty of numerical modeling predictions given the number of simulated waves.


EurOtop (2018): Manual on wave overtopping of sea defences and related structures: An overtopping manual largely based on European research, but for worldwide application. Van der Meer, Allsop, Bruce, De Rouck, Kortenhaus, Pullen, Schüttrumpf, Troch, Zanuttigh.

Gallien (2016): Validated coastal flood modeling at Imperial Beach, California: Comparing total water level, empirical and numerical overtopping methodologies, Coastal Engineering, vol. 111, pp. 95-104.

Pullen et al. (2007): EurOtop wave overtopping of sea defenses and related structures: assessment manual.

Williams, Briganti, Pullen (2014): The role of offshore boundary conditions in the uncertainty of numerical prediction of wave overtopping using non-linear shallow water equations, Coastal Engineering, vol. 89, pp. 30–44.

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Copyright (c) 2023 Nikos Kalligeris, Timu Gallien