Here's a technique I started on last year and never finished. There's two infinite planes. One is flat and water texture, the other angled and the desert texture. That creates a strait line and a slight angle at the intersection. I then went to the terrain editor and created terrain with one side wavey and the rest just square. Flattened it out, put it along the intersection of the land and water planes. Then I copied that lattice, deleted the main part and left only the white waves and foam texture and increased the height of it. In the image, the intersection line in the water between the lattice and water plane can be post render blended. The wet part of the beach where the water drew back needs additional work.