oceanography

"an underwater earthquake in the ocean generates a tsunami with a wavelength of 200 km and a height of 1.5 m. it travels in water that is uniformly deep (3 km) until it reaches an inlet, which is 4 m deep. when it is in the inlet, what will be its:

a. speed ©

b. period (t)

c. wavelength (L)

d. height (h)"

I understand tsunamis are treated as shallow water waves so the equation for speed is c= (gd)^1/2. (g = gravity = 9.8 m/s) and I'm assuming you just use the inlet depth of 4 m to get 6.26 m/second.

what I don't know is the formulas for finding period and wavelength for shallow water waves. I know for deep waves you can use c=L/t where c=(g/2*pi)*t and L=(g/2*pi)*t^2. and (g/2*pi) = 1.56 m/s but I don't have the equations for short water waves.

and I think I have height but If anyone wants to pass along that equation too, that'd be great.

thanks to all.