An oceanography text will spend a chapter or two on the mathematical theory of waves, (and I
don't remember the equations anyway). The longer the interval, the longer the wave length. And
the rest of the wave scales up too, so it reaches deeper. I remember one really nice flat day in
Carmel. There was about a two foot south swell running with a real long interval, about 19 seconds.
You had to look carefully to see the swells, but it was real surgy on the bottom.
Also the energy content of a wave is a function of the third or fourth power of the wave length.
A good lay text is Willard Bascom, Waves and Beaches. It's probably out of print but you can
probably find it used at Amazon. Bascom did a a lot research on West Coast beaches during
and after WW II. One of the things they did was to measure the under water profile of beaches.
You can't use SONAR because of the turbulance, so they used a lead line from DUKWs (WW II
amphibious trucks) There's picture in the book of Bascom in the bow of the truck with the lead
line, in overhead surf at Carmel River State beach.h
