Xbeach | CREST project

Information

https://oss.deltares.nl/web/xbeach/

Xbeach (Roelvink et al., 2009) is a process-based 2D morphodynamic model solving the shallow water equations for the flow. It focuses on nearshore processes and aims at predicting beach and coastline evolutions during storms. For this reason the modelling of wave effects and other cross-shore transport mechanisms are expected to be very detailed. The software is still in development, the manual is not up to date but the code is open source and can hence be adapted to the needs. Morphodynamic computation is long but parallel computing is possible.

Developed by: Unesco-IHE, Deltares, TU Delft and U. Miami (USA)

Location

Nearshore

Variables

Equations

Boundary conditions

Boundary conditions – flow

“left” and “right” lateral boundaries
“front” offshore boundary
“back” boundary

Data needs

Boundary conditions (waves and tides) at the shoreface (just offshore the breaking zone)
All typical data for the calibration of morphological models
At the moment, the model is rather insensitive for the grain size.
- Due to saturation (cmax)
- Simplification of the Van Rijn equations
- Research going on (e.g. JIP project)

Coordinate system

Grid type

Advantages

Weaknesses

At the moment: weak dependency on the grain size for storm conditions
Offshore extension of the domain is limited
No gradients in current velocities along the offshore boundary possible

Calibration

Depending on the problem (hydrodynamics, morphology, long term or storms, …
Excercise for prediction of dune erosion during severe storms in the Netherlands -> WTI settings. Most important (8 parameters differ from the default values):
- Bed slopes for avalanching
- Wave breaker criteria
- Parameters to account for wave skewness and asymetry
- Wave friction

Validation

Normal conditions :Knokke-Heist (IMDC and Fides Engineering for WL/Coastal Division). Modelling of the waves and tides for 3 years.
Good representation of the erosion of the wet beach, the most eastward groin seems to be more effective than modelled
Sedimentation in Baai van Heist below LW remains difficult

Published: Wed, 04/03/2019 - 13:48 | Last updated: Wed, 04/03/2019 - 13:49