Not a clue, to be honest. I'm guessing it has something to do with the shape of =onesixone's terrain, and the fact that the water was really shallow in some spots. Combine that with a bit of tweaking when it comes to the wave width, density, etc., and that was the result. It was pretty much dumb luck
Pity..if you had an idea on how you did it you would have a tut that would rock terragen artist butts!
Really, you know I have seen many great terrangen works, that goes with out saying, but that shore line is really a one of a kind.
I must find out how it was made. I have a new motivation now, well besides beer.