Wave Lab: Run Swell Over the Real Seabed

SurfCheck Wave Lab

Pick a break, then change the swell, wind and tide. The sea is a live wave model running in your browser over the real seabed. It starts at five times real speed so sets come through quickly; switch to real time to feel the true pace. Every seabed says where its depths come from, and anything not measured is hatched.

Survey seabed

MODEL TIME 00:00

deep water shallow sand higher ground, shaded by its real height whitewater where breakers are biggest interpolated or coarse seabed (not measured) close-out (<27°) fast peel (27–40°) makeable (40–70°) slow (>70°) Peel colours only where the seabed is surveyed at 10 m

Shore view · prototype

The same model and the same measured ground, seen from where you would stand. Heights are true to scale unless you switch to ×2. Near the break the lip, curl and spray are drawn by hand from the breaker type, as in the side view: the model itself is a height at each point and cannot fold a wave over. Switch them off to see the model's own surface. Land is only as detailed as the survey behind it.

Cross-section

Tap the map to slice through any spot along the swell; drag to draw your own line. Surface, seabed and breaking come from the simulation; the lip, barrel and whitewater are drawn from the breaker type. Rider is 1.75 m for scale.

Wave by wave

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The small teal square on the map is where this is measured. One second here is one second in the sea when the speed is set to real time. Sets come from seven swell trains of slightly different period and direction drifting in and out of step, the same reason they happen in the sea.

How it works, and what it leaves out

What the model is

A linear wave equation solved in time on the seabed grid, with wave speed at every cell taken from linear dispersion at the swell period. That gives refraction, shoaling, diffraction and reflection. It is a relative of the time-dependent mild-slope models, and much simpler than Boussinesq solvers such as Celeris (Tavakkol & Lynett, 2017), which already do real-time nearshore simulation properly. Breaking is the classic depth limit, wave height ≈ 0.78 × depth, nudged by wind.

How it was checked

On a plain sloping beach the breaker height lands within about 6 to 11% of the Komar & Gaughan (1972) formula. Skill bands come from Hutt, Black & Mead (2001); breaker type from the Iribarren number (Battjes, 1974). Satellite-mapped reef heights were checked against LiDAR at Bundoran: typical error 0.4 m.

What it does not include

Nonlinear shoaling: real waves peak up more sharply before they break.
Currents of any kind: no rips, no tidal streams, no tidal races and no wind-against-tide steepening. At Strandhill the harbour channel matters and is not modelled.
It is not a chart. Depths are resampled survey data with filled-in patches and must never be used for navigation.
Wave set-up, wind-sea growth and a full swell spectrum: the swell here is a handful of clean trains, not a full spectrum.
Sandbars as they are today: sand is drawn as it was on the survey date.
The overturning lip: the barrel in the side view is drawn from the breaker type, not simulated.

What is ours

The physics is textbook. The work here is the seabeds: national surveys, satellite waterlines and LiDAR joined per break, with every cell labelled as measured or filled in. Sources and licences are listed under each map.