Validation of XBeach model for wave run-up

Seyedabdolhossein Mehvar, Ali Dastgheib, Dano Roelvink

Friday 3 july 2015

12:45 - 12:48h at Oceania Foyer (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Flooding along in rivers and coasts, Poster pitches

Parallel session: Poster pitches: 15L. Flood Risk - Flooding

XBeach model is known as a relatively new time-domain wave simulation model that can be used to simulate morphodynamic and hydrodynamic response of the beaches and dunes. This research is aimed to investigate the capability of the XBeach in 1-D transect mode with non-hydrostatic approach for estimation of wave run-up on coastal dikes. Thus, the model is used for numerical simulation of 21 wave cases attacking impermeable dike of Petten sea defense in the Netherlands both for prototype and physical models. The main characteristic of this dike is the complex shallow foreshore which represents interesting cases to investigate its effects on wave transformation and run-up. The simulations have been carried out for two types of cases. Initially, six storm conditions of real field measurements has been simulated by XBeach and in the next step, the model has been used to simulate the same cases when it is scaled down and modelled physically in the flume . For the six real storm conditions which have been measured in the field, XBeach has underestimated 2% wave run-up level, while the XBeach results are in good agreement with all 21 physical model tests. One hypothesis for this difference could be the effect of longshore current and wave dissipation factor in the real case which can considerably influence water level variation and run-up level at the toe of the structure, and is not present in the flume nor in the 1-D transect numerical model. Another reason for having difference between real field measurements and the 1-D numerical and physical models might be the schematization of the foreshore where the real measured bathymetry far from the dike has not been taken into account. In general, this study indicates reasonable results of the model in estimation of 2% probability of exceedance of wave run-up for the simulated cases with complex foreshore slope proving the capability of XBeach in simulating wave run-up level on coastal dikes.