wave speed and depth of water

The deeper the water, the less is the frictional resistance given to the propoagation of waves, as water waves/ripples are mechanical waves invloving vibrational motion of water molecules. As such, the speed of the wave can be increased.

Conversely, in shallow water, frictional resistance experienced by the wave is larger than that in deep water. This would slow down the speed of the wave.

2011-09-08 19:35:37 補充：
The frictional resistance is produced by the bottom of the seabed to the waves in the case of water waves, or the bottom of the vessel to the ripples in the ripple-tank case.