Working out the speed of short wavelength, high amplitude, deepish waves.

jetwaterluffy

I'm trying to work out the speed of a water wave which has a height of ~1/3 of the wavelength and a depth of about half the wavelength and I can't find which equation I need to use. How should I go about it? Any ideas?
EDIT: Like an idiot, I posted this in the wrong section. Can someone move this to classical for me?