Port Beach is a beach with a dune on the east coast of Ireland. In county Louth (North of Dublin). As many beaches, it is slowly changing because of the wind and the currents. My job in Cork is to model this evolution.

First I gathered wave data -a twenty-year series- of the nearest offshore buoy. Then I made an extremal analysis to predict extreme events (or the expected highest event for a given return period) and a trend analysis to build a local wave climate. Easy.

Using a very refined model (the two first were not accurate enough) and a bathymetry of the area I transfered this wave climate to an inshore location near Port Beach. Simple.

Finally, I used this inshore wave climate to calculate the sediment transport. Funny. Or at least funny results.

Jimmy (my tutor): How is your model going?
B.: Not too bad at all. And I've got a good news: in 20 years, your beach will be in England.

After three days stranded with my model, I began the stupid tests. The kind of tests you run just before throwing away your computer or smashing it with your hurley (depending on your country).

First stupid test: reduce the number of data, instead of 12,783 different types of waves, try with only one wave perpendicular to the shore. Result: the dune is moving 150m towards the sea each year. My engineer sense makes me believe that somebody would have noticed that.

Second stupid test: change slightly one of the parameters. Try with a 10-degree angle incoming wave. Result: the dune is moving 150m towards the sea each year. Déjà vu?

Third stupid test: change appreciably one of the parameters. Try a 80-degree angle incoming wave. Result: the dune is moving 150m towards the sea each year. Déjà vu!

Most stupid test: try a physically impossible case. Use a wave coming from the beach. Result: the dune is moving 150m towards the sea each year. Have you seen this movie Groundhog day?