SWASH — The Complete Guide: Free Modelling of Harbour Waves, Overtopping and Coastal Flow
SWASH is an open-source (GPL) model from Delft University of Technology for non-hydrostatic, unsteady flow in coastal areas — a sibling of the SWAN wave model. The essential difference: SWAN computes an averaged spectrum, while SWASH resolves the water surface wave by wave. That is what lets you see what actually happens in a port, a marina or over a structure.
SWASH
Delft University of Technology
Non-hydrostatic coastal flow model — waves in harbours, overtopping of structures and estuary currents.
Get it from the vendorWhat you get
- Wave penetration into harbours — including diffraction around the breakwater head and reflection from walls.
- Harbour resonance — identifying long oscillations that move moored ships.
- Overtopping and run-up — the volume of water passing over a breakwater or seawall.
- Breaking and run-up on beaches — in the surf zone itself.
- Density-driven currents — in estuaries, seas and lakes, on structured and unstructured meshes with parallel computing.
When to choose it
When the question is about individual waves rather than averages: mooring comfort, overtopping of an embankment or resonance. It is heavier to run than SWAN, so a common workflow is to run SWAN over a large area and feed the result as a boundary condition to SWASH on a small one.
Related tools
For waves over a wide area — SWAN. For beach erosion during a storm — XBeach. For long-term currents and sediment — Delft3D.
SWAN
Delft University of Technology
Nearshore wave model for shallow water — essential input for jetty and breakwater design.
Get it from the vendorXBeach
Deltares
Storm impact on the coast — overwash, dune erosion and barrier breaching in a single extreme event.
Get it from the vendorDelft3D
Deltares
Coastal and marine engineering — currents, waves, sediment transport and shoreline morphology.
Get it from the vendor
TELEMAC-MASCARET
EDF / Consortium
Hydrodynamic system for rivers and coasts on unstructured meshes — flow, waves, sediment and quality.
Get it from the vendorThe bottom line
SWASH is the free tool for questions where the individual wave matters — ports, marinas and protective structures. Free for commercial use too.