Wave base

The wave base is the maximum depth at which a water wave's passage causes significant water motion. For water depths larger than the wave base, bottom sediments are no longer stirred by the wave motion above.

In deep water, the water particles are moved in a circular orbital motion when a wave passes. The radius of the circle of motion for any given water molecule decreases exponentially with increasing depth. The wave base, which is the depth of influence of a water wave, is about half the wavelength. At depths greater than half the wavelength, the water motion is less than 4% of its value at the water surface [At a depth of half the wave length, the amplitude of the water particle motion by the waves has been reduced to "e^-π ≈ 0.04" times it value at the water surface.] , and may be neglected.

For instance, in a pool of water 1 foot deep, a wave with a 2-foot wavelength would barely be moving the water at the bottom. In the same pool, a wave with a wavelength of 1 foot would not be able to cause water movement on the bottom.

ee also

*Airy wave theory
*Dispersion (water waves)
*Waves and shallow water

References

*cite book | title=Water wave mechanics for engineers and scientists | author=R. G. Dean and R. A. Dalrymple | year=1991 | series=Advanced Series on Ocean Engineering | volume=2 | publisher=World Scientific, Singapore | isbn=978-9810204204

Notes