|Wave Transformations are the basis for
designing coastal structures. Here, we will look at three wave
transformations: shoaling, refraction, and
diffraction. Although all of these process occur naturally, it is
imperative to examine how the structure will effect the
current conditions of the target coastal environment, in addition to
those surrounding it.
As the water becomes more shallow as it reaches the coast, the waves slow down and become closer together and steeper.
There are many effects to shoaling, most importantly: energy dissipation and sediment transport.
The gradual shallowing of the seabed allows the energy in waves to slowly dissipate. Therefore, waves are not as aggresive when they reach the shoreline. If a coastal structure were placed at the shoreline that created an abrupt stop for the waves, energy dissipation would be more extreme.
Since shoaling involves the effects that waves have with the bottom of the seabed, sediment transport is a big issue. The wave's energy dissipation occurs because of friction with the shallowing bottom. This will cause sediments to be suspended in the water, and released once the energy dissipates.
Shoaling is a natural process, and human interference with coastal areas has created unnatural slopes and bluffs, and encouraged sediment transport with alterations to the coastline.
Refraction occurs when the direction of a wave changes with the bottom contours as the wave approaches the coastline.
Please refer to the following link for an animation demonstrating how refraction occurs and effects our coastlines. Select "Wave Refraction" and "Show Coastal Erosion."